Proxima Centauri b

Proxima Centauri b (also called Proxima b or Alpha Centauri Cb) is an exoplanet orbiting in the habitable zone of the red dwarf star Proxima Centauri, which is the closest star to the Sun and part of a triple star system. It is approximately from Earth in the constellation Centaurus, making it and Proxima c the closest known exoplanets to the Solar System.
Proxima Centauri b orbits the star at a distance of roughly with an orbital period of approximately 11.2 Earth days, and has an estimated mass of at least 1.2 times that of Earth. It is subject to stellar wind pressures of more than 2,000 times those of Earth from the solar wind, and its habitability has not yet been definitively established.
The planet's discovery was announced in August 2016. It was found using the radial velocity method, where periodic Doppler shifts of the parent star's spectral lines suggest an orbiting object. From these readings, the parent star's radial velocity relative to the Earth is varying with an amplitude of about 1.4 metres (4.5 feet) per second. According to Guillem Anglada‐Escudé, the planet's proximity to Earth offers an opportunity for robotic exploration with the Starshot project or, at least, "in the coming centuries".
Without its orbital inclination known, Proxima Centauri b's exact mass is unknown. If its orbit is nearly edge-on, it would have a mass of (Earth masses). Statistically, there is a roughly 90% chance that its mass is less than .
In May 2019, a paper presenting recent Spitzer Space Telescope data concluded that Proxima Centauri b did not transit its sun relative to Earth, and attributed previous transit detections to correlated noise.
Physical characteristics.
Mass, radius, and temperature.
The apparent inclination of Proxima Centauri b's orbit has not yet been measured. The minimum mass of Proxima b is , which would be the actual mass if its orbit were seen edge-on from the Earth. Once its orbital inclination is known, the mass will be calculable. More tilted orientations imply a higher mass, with 90% of possible orientations implying a mass below . The planet's exact radius is unknown. If it has a rocky composition and a density equal to Earth's, its radius is at least . It could be larger if it has a lower density than Earth, or a mass higher than the minimum mass. Like many super-Earth sized planets, Proxima Centauri b may have an icy composition like Neptune, with a thick enveloping hydrogen and helium atmosphere; this likelihood has been calculated to be greater than 10%. The planet has an equilibrium temperature of , somewhat colder than Earth’s .
If Proxima Centauri b's orbit is coplanar with that of the candidate exoplanet Proxima Centauri c, estimates of whose true mass were recently calculated using various combinations of its spectroscopic orbital parameters, Gaia DR2 proper motion anomaly, and astrometric measurements, then a true mass of Proxima b can be estimated. For example, a 2020 paper published by Kervella et al. estimated Earth masses, and another by Benedict et al. estimated Earth masses as true mass values for Proxima b.
Host star.
The planet orbits an M-type red dwarf named Proxima Centauri. The star has a mass of and a radius of . It has a surface temperature of 3042 K and is 4.85 billion years old. In comparison, the Sun is 4.6 billion years old and has a surface temperature of 5778 K. Proxima Centauri rotates once roughly every 83 days, and has a luminosity about . Like the two larger stars in the triple star system, Proxima Centauri is rich in metals compared with the Sun, something not normally found in low-mass stars like Proxima. Its metallicity ([Fe/H]) is 0.21, or 1.62 times the amount found in the Sun's atmosphere.
Even though Proxima Centauri is the closest star to the Sun, it is not visible to the unaided eye from Earth because of its low luminosity (average apparent magnitude of 11.13).
Proxima Centauri is a flare star. This means that it undergoes occasional dramatic increases in brightness and high-energy emissions because of magnetic activity that would create large solar storms. On 18 March 2016, a superflare was observed with an energy of 1026.5 joules. The March 2016 flare reached about 68 times usual level, thus a little brighter than the Sun. The surface irradiation was estimated to be 100 times what is required to kill even UV-hardy microorganisms. Based on the rate of observed flares, total ozone depletion of an Earth-like atmosphere would occur within several hundred thousand years.
Orbit.
Proxima Centauri b orbits its host star every 11.186 days at a semi-major axis distance of approximately , which means the distance from the exoplanet to its host star is one-twentieth of the distance from the Earth to the Sun. Comparatively, Mercury, the closest planet to the Sun, has a semi-major axis distance of 0.39 AU. Proxima Centauri b receives about 65% of the amount of radiative flux from its host star that the Earth receives from the Sun – for comparison, Mars receives about 43%. Most of the radiative flux from Proxima Centauri is in the infrared spectrum. In the visible spectrum the exoplanet receives only ~3% of the PAR (400–700 nm) of Earth irradiance – for comparison, Jupiter receives 3.7% and Saturn 1.1%. – so it would usually not get much brighter than twilight anywhere on Proxima Centauri b's surface. The maximum illumination of horizontal ground by twilight at sunrise is about 400 lux, while the illumination of Proxima b is about 2700 lux with a quiet Proxima. Proxima also has flares. The brightest flare observed until 2016 had increased the visual brightness of Proxima about 8 times, which would be a large change from the previous level but, at about 17% the illumination of Earth, not very strong sunlight. However, because of its tight orbit, Proxima Centauri b receives about 400 times more X-ray radiation than the Earth does.
Habitability.
The habitability of Proxima Centauri b has not been established, but the planet is subject to stellar wind pressures of more than 2,000 times those experienced by Earth from the solar wind. This radiation and the stellar winds would likely blow any atmosphere away, leaving the subsurface as the only potentially habitable location on that planet.
The exoplanet is orbiting within the habitable zone of Proxima Centauri, the region where, with the correct planetary conditions and atmospheric properties, liquid water may exist on the surface of the planet. The host star, with about an eighth of the mass of the Sun, has a habitable zone between ∼0.0423–0.0816 AU. In October 2016, researchers at France's CNRS research institute stated that there is a considerable chance of the planet harboring surface oceans and having a thin atmosphere. However, unless the planet transits in front of its star from the perspective of Earth, it is difficult to test these hypotheses.
Tidal effects and stellar flares.
Even though Proxima Centauri b is in the habitable zone, the planet's habitability has been questioned because of several potentially hazardous physical conditions. The exoplanet is close enough to its host star that it might be tidally locked. In this case, it is expected that any habitable areas would be confined to the border region between the two extreme sides, generally referred to as the terminator line, since it is only here that temperatures might be suitable for liquid water to exist. If the planet's orbital eccentricity is 0, this could result in synchronous rotation, with one hot side permanently facing towards the star, while the opposite side is in permanent darkness and freezing cold. However, Proxima Centauri b's orbital eccentricity is not known with certainty, only that it is below 0.35—potentially high enough for it to have a significant chance of being captured into a 3:2 spin-orbit resonance similar to that of Mercury, where Proxima b would rotate around its axis approximately every 7.5 Earth days with about 22.4 Earth days elapsing between one sunrise and the next. Resonances as high as 2:1 are also possible. Another problem is that the flares released by Proxima Centauri could have eroded the atmosphere of the exoplanet. However, if Proxima b had a strong magnetic field, the flare activity of its parent star would not be a problem.
Climate and atmosphere possibilities.
If water and an atmosphere are present, a far more hospitable environment would result. Assuming an atmospheric N2 pressure of 1 bar and ∼0.01 bar of CO2, in a world including oceans with average temperatures similar to those on Earth, a wide equatorial belt (non-synchronous rotation), or the majority of the sunlit side (synchronous rotation), would be permanently ice-free. A large portion of the planet may be habitable if it has an atmosphere thick enough to transfer heat to the side facing away from the star. If it has an atmosphere, simulations suggest that the planet could have lost about as much as the amount of water that Earth has due to the early irradiation in the first 100–200 million years after the planet's formation. Liquid water may be present only in the sunniest regions of the planet's surface in pools either in an area in the hemisphere of the planet facing the star or—if the planet is in a 3:2 resonance rotation—diurnally in the equatorial belt. All in all, astrophysicists consider the ability of Proxima Centauri b to retain water from its formation as the most crucial point in evaluating the planet's present habitability. The planet may be within reach of telescopes and techniques that could reveal more about its composition and atmosphere, if it has any.
If an atmosphere is present, longer-wavelength radiation, from the red dwarf parent star means that weather will be affected. Cloud formation on the day side of the planet will be inhibited, compared to Earth (or Venus), resulting in clearer skies.
View from Proxima Centauri b.
Viewed from near the Alpha Centauri system, the sky would appear much as it does for an observer on Earth, except that Centaurus would be missing its brightest star. The Sun would be a yellow star of an apparent magnitude of +0.5 in eastern Cassiopeia, at the antipodal point of Alpha Centauri's current right ascension and declination, at (2000). This place is close to the 3.4-magnitude star ε Cassiopeiae. Because of the placement of the Sun, an interstellar or alien observer would find the \/\/ of Cassiopeia had become a /\/\/ shape nearly in front of the Heart Nebula in Cassiopeia. Sirius lies less than a degree from Betelgeuse in the otherwise unmodified Orion and with a magnitude of −1.2 is a little fainter than from Earth but still the brightest star in the Alpha Centauri sky. Procyon is also displaced into the middle of Gemini, outshining Pollux, whereas both Vega and Altair are shifted northwestward relative to Deneb (which barely moves, due to its great distance), giving the Summer Triangle a more equilateral appearance.
From Proxima Centauri b, Alpha Centauri AB would appear like two close bright stars with the combined apparent magnitude of −6.8. Depending on the binary's orbital position, the bright stars would appear noticeably divisible to the naked eye, or occasionally, but briefly, as a single unresolved star. Based on the calculated absolute magnitudes, the apparent magnitudes of Alpha Centauri A and B would be −6.5 and −5.2, respectively.
Formation.
It is unlikely that Proxima Centauri b originally formed in its current orbit since disk models for small stars like Proxima Centauri would contain less than one of matter within the central one AU at the time of their formation. This implies that either Proxima Centauri b was formed elsewhere in a manner still to be determined, or the current disc models for stellar formation are in need of revision.
Discovery.
The first indications of the exoplanet were found in 2013 by Mikko Tuomi of the University of Hertfordshire from archival observation data. To confirm the possible discovery, a team of astronomers launched the Pale Red Dot project in January 2016. On 24 August 2016, the team of 31 scientists from all around the world, led by Guillem Anglada-Escudé of Queen Mary University of London, confirmed the existence of Proxima Centauri b through their research, published in a peer-reviewed article in "Nature".
The measurements were done using two spectrographs, HARPS on the ESO 3.6 m Telescope at La Silla Observatory and UVES on the 8-metre Very Large Telescope. The peak radial velocity of the host star combined with the orbital period allowed for the minimum mass of the exoplanet to be calculated. The chance of a false positive detection is less than one in ten million.
Observational complications of the star tend to indicate additional, not insignificant size, orbiting planets. Another super-Earth was noted on discovery of this planet as possible; its presence would not destabilize the orbit of Proxima Centauri b. One very large super-Earth was discovered in 2019, known as Proxima Centauri c – it orbits at 1.5 AU away, too far to tug on the other planet at all significantly.
Data of ESPRESSO excludes extra companions with masses above 0.6  at periods shorter than 50 days. A potential companion, Proxima Centauri d, at 0.29 , was found to have an orbit around 5.15 days. It requires further study, to confirm its existence and identify its orbital properties.
Future observations.
A team of scientists think they can image Proxima Centauri b and probe the planet's atmosphere for signs of oxygen, water vapor, and methane, combining ESPRESSO and SPHERE on the VLT. The James Webb Space Telescope may be able to characterize the atmosphere of Proxima Centauri b, but there is no conclusive evidence for transits combining MOST and HATSouth photometry, giving it less than a 1 percent chance of being a transiting planet. Future telescopes (the Extremely Large Telescope, the Giant Magellan Telescope, and the Thirty Meter Telescope) could have the capability to characterize Proxima Centauri b.
The discovery of Proxima b was significant to Breakthrough Starshot, a proof of concept project aiming to send a fleet of miniature probes to the Alpha Centauri system. The project is led by research company Breakthrough Initiatives, and plans to develop and launch a fleet of miniature unmanned spacecraft called StarChips, which could travel at up to 20% of the speed of light, arriving at the system in roughly 20 years with notification reaching Earth a little over 4 years later.
2069 Alpha Centauri mission.
In 2017, Breakthrough Initiatives and the European Southern Observatory (ESO) entered a collaboration to enable and implement a search for habitable planets in the nearby star system, Alpha Centauri. The agreement involves Breakthrough Initiatives providing funding for an upgrade to the VISIR (VLT Imager and Spectrometer for mid-Infrared) instrument on ESO's Very Large Telescope (VLT) in Chile.


U Vulpeculae

U Vulpeculae is a variable and binary star in the constellation Vulpecula.
It is a classical Cepheid variable and its apparent magnitude ranges from 6.73 to 7.54 over a precise cycle of 7.99 days. Its variable nature was discovered in 1898 at Potsdam Observatory by Gustav Müller and Paul Kempf.
In 1991 a study of radial velocities showed that it U Vulpeculae is a spectroscopic binary and a full orbit with a period of 2510 days (6.9 years) was first calculated in 1996. The secondary star is invisible and is only known from its effect on the motion of the primary.


NGC 6426

NGC 6426 is a globular cluster located in the constellation Ophiuchus. It is designated IX in the galaxy morphological classification scheme and was discovered by the British astronomer William Herschel on 3 June 1786. It is at a distance of 67,500 light years away from earth.<ref name="NASA/IPAC"></ref>


Upsilon Andromedae e

Upsilon Andromedae e is the outermost extrasolar planet orbiting the star Upsilon Andromedae in the constellation of Andromeda. This planet is one of the most Jupiter-like exoplanets found in terms of mass and semi-major axis.
Discovery.
This planet was discovered on November 22, 2010, but the discovery paper was not released until December 2. It was the fourth time in 2010 that a fourth planet has been discovered in a planetary system, the others being Gliese 876 e, HD 10180 e, and HR 8799 e; in no other year so far during the exoplanet era has more than one fourth planet been discovered.
Astronomers originally thought that this planet could not exist because it would have made the planetary system unstable and would have been ejected. But in 2007, an island region of stability was reported where a fourth planet could exist.
Characteristics.
Upsilon Andromedae e has a mass slightly greater than Jupiter's and orbits at a similar distance as Jupiter from the Sun, at precisely 5.2456 AU compared to 5.2043 AU for Jupiter. Although only the minimum mass is determined since inclination is not yet known, its true mass might be much greater. It takes over a decade to orbit the star. At an eccentricity of 0.00536, the planet's orbit is more circular than that of any of the planets in our solar system.
Other authors, while confirming evidence for a fourth planet, challenge the values found, since they use a data set inconsistent with the others.


Eta Sagittae

Eta Sagittae (η Sagittae) is solitary star in the northern constellation of Sagitta. It is faintly visible to the naked eye, having an apparent visual magnitude of +5.09. Based upon an annual parallax shift of , it is approximately distant from the Sun. There is a 61.1% chance that it is a member of the Hyades-Pleiades stream of stars that share a common motion through space.
This is an evolved K-type giant star with a stellar classification of K2 III. At the age of about 1.7 billion years, it is now a red clump star that is generating energy through the fusion of helium at its core. Eta Sagittae has 1.7 times the mass of the Sun and has expanded to seven times the Sun's radius. It is radiating 25.7 times the Sun's luminosity from its photosphere at an effective temperature of .


Beta Capricorni

Beta Capricorni (β Capricorni, abbreviated Beta Cap, β Cap) is a multiple star system in the constellation of Capricornus and located 328 light-years from the Sun. Because it is near the ecliptic, Beta Capricorni can be occulted by the Moon, and also (rarely) by planets.
The system is believed to consist of five stars. With binoculars or a small telescope, Beta Capricorni can be resolved into a binary pair. The brighter of the two is designated Beta¹ Capricorni or Beta Capricorni A; the dimmer, Beta² Capricorni or Beta Capricorni B. Both are themselves made up of multiple stars. Beta¹ Capricorni has three components; a single star designated Beta Capricorni Aa (formally named Dabih , the traditional name of the system) and a binary pair, Beta Capricorni Ab (whose two components are designated Beta Capricorni Ab1 and Ab2). Beta² Capricorni is also a binary pair, with components designated Beta Capricorni Ba and Bb.
Two other nearby stars were discovered by John Herschel. Sometimes referred to as Beta Capricorni D and E, it is unclear whether they are simply optical doubles or part of the Beta Capricorni system.
Nomenclature.
"β Capricorni" (Latinised to "Beta Capricorni") is the system's Bayer designation; "β¹" and "β² Capricorni" those of its two constituents. The designations of the two constituents as "Beta Capricorni A" and "B", and those of the sub-components - "Beta Capricorni Aa", "Ab", "Ab1", "Ab2", "Ba" and "Bb" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
"Beta Capricorni" bore the traditional name "Dabih", deriving from the Arabic الذابح "al-dhābiḥ" "the butcher", with "Beta¹" and "Beta²" subsequently named "Dabih Major" and "Dabih Minor", respectively. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name "Dabih" for the component "Beta Capricorni Aa" on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Ox (asterism)", refers to an asterism consisting of Beta Capricorni, Alpha² Capricorni, Xi² Capricorni, Pi Capricorni, Omicron Capricorni and Rho Capricorni. Consequently, the Chinese name for Beta Capricorni itself is (, ).
Properties.
Beta¹ Capricorni is the brighter of the two components with an apparent magnitude of +3.05, while the dimmer Beta² Capricorni has an apparent magnitude of +6.09. The two components are separated by 3.5 arcminutes on the sky, putting them at least 21,000 AU (0.34 light-years) apart. They take approximately 700,000 years to complete one orbit.
Hierarchy of orbits in the β Capricorni system
Beta¹ Capricorni.
Beta¹ Capricorni is the more complex of the pair and has a spectrum that is difficult to interpret. Its dominant pair of stars are the orange K-type bright giant Beta Capricorni Aa, with an apparent magnitude of +3.08, and the blue-white B-Type main sequence dwarf Beta Capricorni Ab1 with an apparent magnitude of +7.20. They are separated by 0.05 arcseconds (5 AU) and have an orbital period of 3.77 years.
The Aa component has a surface temperature of 4900 kelvins, a radius 35 times that of the Sun, and a luminosity 600 times that of the Sun. The Ab1 component's unseen companion, Beta Capricorni Ab2, orbits Ab1 with an orbital period of 8.7 days.
Beta¹ Capricorni is 4.6 degrees north of the ecliptic, so it can be occulted by the Moon.
Beta² Capricorni.
Beta² Capricorni is simpler and more studied. Its brighter component, Beta Capricorni Ba, has a magnitude of 6.1 and is an A0-giant with 40 times the luminosity of the Sun. The companion, Beta Capricorni Bb, is approximately 3 arcseconds from Ba. Ba is unusual for having large amounts of mercury and manganese in its atmosphere.
Beta Capricorni D and E.
These lie 112 arcseconds away from Beta¹ Capricorni.


Beta Scorpii

Beta Scorpii (β Scorpii, abbreviated Beta Sco, β Sco) is a multiple star system in the southern zodiac constellation of Scorpius. It bore the traditional proper name of Acrab , though the International Astronomical Union now regards that name as applying only to the β Scorpii Aa component.
Components.
Observed through a small telescope, Beta Scorpii appears as a binary star with a separation between the two components of 13.5 arcseconds and a combined apparent magnitude of 2.50. This pair, designated β¹ Scorpii and β² Scorpii, form the top branches of a hierarchy of six orbiting components.
Hierarchy of orbits in the β Scorpii system
β¹ Scorpii, the brighter of the pair, consists of two sub-components, designated β Scorpii A and β Scorpii B, orbiting at an angular separation of 0.3 arcseconds with an orbital period of 610 years. β Scorpii A is itself a spectroscopic binary, with the two components designated β Scorpii Aa (also named Acrab) and β Scorpii Ab. They are separated by 1.42 milliarcseconds and have an orbital period of 6.82 days.
β² Scorpii also has two sub-components, designated β Scorpii C and β Scorpii E, orbiting at an angular separation of 0.1328 arcseconds with an orbital period of 39 years. β Scorpii E in turn is a spectroscopic binary with components designated β Scorpii Ea and β Scorpii Eb and having an orbital period of 10.7 days.
Component β Scorpii D is the unrelated seventh magnitude star HD 144273, 520" away. Some authors have also referred to component Ab as D.
A companion to component B, β Scorpii G, has been proposed to account for missing mass in the system, but no further evidence of its existence has been found. β Scorpii F refers to a theorised companion to component E.
Nomenclature.
"β Scorpii" (Latinised to "Beta Scorpii") is the star's Bayer designation; "β¹" and "β² Scorpii", those of its two components. The designations of the sub-components - "β Scorpii A", "Aa", "Ab", "B", "C", "E", "Ea" and "Eb" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Beta Scorpii bore the traditional names "Acrab", "Akrab" or "Elacrab", all deriving from the Arabic name () "al-'Aqrab" 'the Scorpion' for the whole constellation, as well as Graffias , Italian for "the claws", a name it shared with Xi Scorpii.
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name "Acrab" for the component "β Scorpii Aa" on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Room", refers to an asterism consisting of both of β1 Scorpii and β2 Scorpii, π Scorpii, ρ Scorpii and δ Scorpii, . Consequently, the Chinese name for both of β1 Scorpii and β2 Scorpii is (), "the Fourth Star of Room".
Namesake.
USS Graffias (AF-29) was once a United States navy ship named after the star.
Properties.
The β Scorpii system is a kinematic member of the Upper Scorpius subgroup of the Scorpius-Centaurus Association, a group of thousands of young stars with mean age 11 million years at distance 470 light years (145 parsecs). Analysis of β1 Scorpii as a single star derived an evolutionary age between 9 and 12 million years, but analysis of the β Scorpii system as a whole suggest an age closer to 6 million years.
The two components of β Scorpii A are the most massive members of the system, and respectively. The combined spectral type is B1 V. The individual spectral types cannot be clearly measured, but are estimated to be B0.5 and B1.5. Component Aa is evolving slightly away from the zero age main sequence and its luminosity class is estimated to be intermediate between subgiant (IV) and main sequence (V). Component Ab has a main sequence luminosity class, a temperature of 26,400 K, and a luminosity of .
Component B is over 20 times fainter than the combined component A stars and a clear spectral type has not been measured. Its mass is estimated to be approximately .
Component C has a stellar classification of B2 V and a mass of . It has an effective surface temperature of 24,000 K, a radius of and a bolometric luminosity of .
Component E is determined to have a temperature of 13,000 K, radius of , and luminosity of . It is chemically peculiar, with high abundances of manganese and strontium. It is possibly a mercury-manganese (HgMn) star, but abundances of other metals are unexpectedly low.
Beta Scorpii is 1.01 degree from the ecliptic and can be occulted by the Moon and, very rarely, by planets. On December 9, 1906, it was occulted by Venus. The last occultation by a planet took place on 13 May 1971, by Jupiter.
In culture.
Beta Scorpii appears on the flag of Brazil, symbolising the state of Maranhão.


Ramus Pomifer

Ramus Pomifer (Latin for "apple branch") was a constellation between Hercules and Lyra.
It was depicted in the form of a branch held in Hercules' left hand. The also obsolete constellation of Cerberus - made up of much the same stars - became combined with it in later depictions, with the name "Cerberus et Ramus".


NGC 7098

NGC 7098 is a doubled barred spiral galaxy located about 95 million light-years away from Earth in the constellation of Octans. NGC 7098 has an estimated diameter of 152,400 light-years. NGC 7098 was discovered by astronomer John Herschel on September 22, 1835.
Characteristics.
NGC 7098 has a very prominent bar that is shaped like a broad oval with very prominent, nearly straight ansae. Surrounding the bar, an inner ring made of four tightly wrapped spiral arms is found. Located outside of the inner ring, a well-defined outer ring surrounding the inner region appears to have formed due to the wrapping of two spiral arms. It appears that both rings are being affected by new star formation. However, there is no star formation in the core of NGC 7098 as shown by the absence of dust lanes.


HD 79940

HD 79940 is a single star in the southern constellation of Vela. It has the Bayer designation of k Velorum; "HD 79940" is the identifier from the "Henry Draper Catalogue". This star has a yellow-white hue and is faintly visible to the naked eye as a point light source with an apparent visual magnitude of 4.63. It is located at a distance of approximately 158 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +6 km/s.
There has been some disagreement over the stellar classification of this star. In 1975, S. Maladora found a class of F5III, suggesting an evolved F-type star, matching an earlier (1957) classification by A. de Vaucouleurs. N. Houk assigned it a class of F3/5V in 1979, matching an F-type main-sequence star. It has a high rate of spin with a projected rotational velocity of . This may explain why it was incorrectly classified as a spectroscopic binary in 1972.
There is a faint magnitude 14.50 companion at an angular separation of along a position angle of 126° from the brighter star. This was discovered by T. J. J. See in 1897.


NGC 6560

NGC 6560 is a spiral galaxy located in the constellation Hercules. It was discovered by Lewis A. Swift on 22 October 1886.


NO Aurigae

NO Aurigae is a pulsating variable star in the constellation Auriga.
Variability.
NO Aurigae is listed in the General Catalogue of Variable Stars as a slow irregular variable, indicating that no regularity could be found in the brightness variations. Other studies have suggested possible periods of 102.1, 173, and 226 days, and would classify it as a semiregular variable star. The maximum visual magnitude range is 6.05–6.50.
Properties.
Most studies of NO Aurigae treat it as a supergiant member of the Auriga OB1 stellar association at about 1.4 kpc. On this basis it has a luminosity around and a radius around .
NO Aurigae is an MS star, intermediate between spectral type M and S. These are typically Asymptotic Giant Branch stars which can appear with supergiant spectra due to their large size and low mass. Possible detection of Technetium in the spectrum is a symptom of the third dredge-up which occurs only in late AGB stars. The revised Hipparcos parallax places it at 595 pc, around the third of the distance of Aur OB1, suggesting about a tenth of the derived luminosity for NO Aur. Calculations using this distance give luminosities of , , or .


Zeta Pyxidis

Zeta Pyxidis (ζ Pyxidis) is a wide binary star system in the southern constellation of Pyxis. It is visible to the naked eye with a combined apparent visual magnitude of +4.88. Based upon an annual parallax shift of 13.35 mas as seen from Earth, it is located around 244 light years from the Sun.
The yellow-hued primary, component A, is an evolved G-type giant star with a stellar classification of , where the suffix notation indicating it has anomalously weak lines of cyanogen. At the age of 1.88 billion years, is a red clump star that is generating energy through the fusion of helium at its core. The primary has nearly double the mass of the Sun and is radiating 69 times the Sun's luminosity from its photosphere at an effective temperature of 4,876 K.
The companion, component B, is a magnitude 9.59 star at an angular separation of 52.20 arc seconds along a position angle of 61°, as of 2010.


R Cassiopeiae

R Cassiopeiae is a variable star in the northern constellation of Cassiopeia. It is located approximately 574 light years distant from the Sun, but is drifting closer with a radial velocity of −23 km/s. This is a pulsating Mira-type variable star with a brightness varies from magnitude +4.4 down to +13.5 with a period of 433.6 days. At its maximum, R Cassiopeiae is visible to the naked eye as a faint, red-hued star.
This aging red giant star has a stellar classification that varies from M6e to M10e, where the 'e' suffix indicates emission features in the spectrum. Currently on the asymptotic giant branch, it has 59% of the mass of the Sun with an oxygen rich chemical abundance. Having exhausted the supply of hydrogen at its core, the star has expanded to 263–310 times the Sun's radius. On average, the star is radiating 3,837 times the luminosity of the Sun from its swollen photosphere with an effective temperature ranging around 2,812 K. It is losing mass at the rate of and is surrounded by a dusty circumstellar shell that extends out to .


Epsilon Geminorum

Epsilon Geminorum (ε Geminorum, abbreviated Epsilon Gem, ε Gem), formally named Mebsuta , is a star in the constellation of Gemini, on the outstretched right 'leg' of the twin Castor. The apparent visual magnitude of +3.06 makes it one of the brighter stars in this constellation. The distance to this star can be determined by parallax measurements, giving a value of , with a margin of error of .
Nomenclature.
"ε Geminorum" (Latinised to "Epsilon Geminorum") is the star's Bayer designation. It bore the traditional names "Mebsuta", "Melboula" or "Melucta". "Mebsuta" has its roots in ancient Arabic where it and the star Mekbuda (Zeta Geminorum) were the paws of a lion. "Mebsuta" ('Mabsūṭah' مبسوطة) comes from a phrase referring to the outstretched paw. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included "Mebsuta" for this star.
In Chinese, (), meaning "Well (asterism)", refers to an asterism consisting of ε Geminorum, μ Geminorum, ν Geminorum, γ Geminorum, ξ Geminorum, 36 Geminorum, ζ Geminorum and λ Geminorum. Consequently, ε Geminorum itself is known as (, .)
Properties.
The spectrum of this star matches a stellar classification of G8 Ib, where the luminosity class of Ib indicates this is a lower luminosity supergiant star. Alternatively, it may be a star that has passed through the asymptotic giant branch stage and possesses a detached shell of dust. The estimated mass of this star is over 19 times the mass of the Sun, and it has expanded to a radius measured at around 105–175 times that of the Sun. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.
Epsilon Geminorum is radiating around 8,500 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 4,662 K. It is this temperature that gives it the yellow-hued glow of a G-type star. A surface magnetic field with a strength of has been detected on this star. This topologically complex field is most likely generated by a dynamo formed from the deep convection zone in the star's outer envelope.
Occultations.
Epsilon Geminorum lies near the ecliptic, so it can be occulted by the Moon or a planet. Such an occultation took place on April 8, 1976 by Mars, which allowed the oblateness of the planet's outer atmosphere to be measured. Epsilon Geminorum was occulted by Mercury on June 10, 1940, and on September 3, 2015 it was occulted by the asteroid Iphigenia.
In culture.
USS Melucta (AK-131) was a United States Navy Crater class cargo ship named after the star.


Iota Hydrae

Iota Hydrae (ι Hydrae, abbreviated Iota Hya, ι Hya), formally named Ukdah , is a star in the constellation of Hydra, about 8° to the north-northwest of Alphard (Alpha Hydrae) and just to the south of the celestial equator. Visible to the naked eye, it is a suspected variable star with an apparent visual magnitude that ranges between 3.87 and 3.91. Based upon an annual parallax shift of 12.39 mas measured during the Hipparcos mission, it is located around 263 light-years from the Sun.
Nomenclature.
"ι Hydrae" (Latinised to "Iota Hydrae") is the star's Bayer designation.
This star along with Tau¹ Hydrae, Tau² Hydrae and 33 Hydrae (A Hydrae), were Ptolemy's Καμπή (Kampē); but Kazwini knew them as عقدة "ʽuqdah" (or "ʽuḳdah") "knot". According to a 1971 NASA memorandum, "Ukdah" was the name of an asterism of four stars: Tau¹ Hydrae as "Uḳdah I", Tau² Hydrae as "Uḳdah II", 33 Hydrae as "Uḳdah III" and Iota Hydrae as "Uḳdah IV". In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name "Ukdah" for Iota Hydrae on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Star (asterism)", refers to an asterism consisting of ι Hydrae, Alphard, τ1 Hydrae, τ2 Hydrae, 26 Hydrae, 27 Hydrae, HD 82477 and HD 82428. Consequently, ι Hydrae are known as (, ).
Properties.
This is an evolved K-type giant star with a stellar classification of K2.5 III. It is a Barium star, which means that, for a giant star, it displays unusually strong absorption lines of singly-ionized barium and strontium. Iota Hydrae has nearly twice the mass of the Sun and has expanded to 33 times the Sun's radius. It is around 2.5 billion years old and is spinning with a leisurely projected rotational velocity of 4.5 km/s. It may be a member of the Wolf 630 moving group of stars that share a common trajectory through space.


Omega Cancri

The Bayer designation ω Cancri (Omega Cancri) is shared by two stars in the constellation Cancer:


HD 89307

HD 89307 is a star in the equatorial constellation of Leo. It is too faint to be viewed with the naked eye except under ideal conditions, having an apparent visual magnitude of 7.02. The star is located at a distance of 105 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +23 km/s.
This is an ordinary G-type main-sequence star with a stellar classification of G0V. It is chromospherically inactive and appears older than the Sun with a rotation period of 23.7 days. The star has about the same mass as the Sun and is 8% larger. It is radiating 1.35 times the Sun's luminosity from its photosphere at an effective temperature of 5,950 K.
Planetary system.
In December 2004, using the radial velocity method, it was found to have a long-period giant planet in orbit around it.


NGC 3009

NGC 3009 is a lenticular galaxy in the constellation of Ursa Major. It is about 35 thousand light years across, and with a recessional velocity of 4,445 kilometers per second, is at a distance of 205 million light years from the sun. NGC 3009 is also known by the catalog name of PGC 28330, and is often mistaken for the dimmer PGC 28303. This is due to the fact that these objects are very close to each other in the sky, and the astronomer Dreyer misinterpreted John Herschel's original March 17, 1828 record of the galaxy, mistaking it for one a few arcminutes to the west (which is now known as PGC 28303). Herschel would have been unable to see PGC 28303 as anything but a background star, due to his less advanced telescope at the time.


Kepler-32

Kepler-32 is an M-type main sequence star located about 1070 light years from Earth, in the constellation of Cygnus. Discovered in January 2012 by the Kepler spacecraft, it shows a 0.58 ± 0.05 solar mass (), a 0.53 ± 0.04 solar radius (), and temperature of 3900.0 K, making it half the mass and radius of the Sun, two-thirds its temperature and 5% its luminosity.
Planetary system.
In 2011, 2 planets orbiting around it, were discovered, and two more suspected. The smaller Kepler-32b, orbiting its parent star every 5.90124 days, and Kepler-32c with an orbital period of 8.7522 days. In April 2013, transit-timing variation analysis confirmed 3 other planets to be in the system. However, only very loose constraints of the maximum mass of the planets could be determined.
In 2014, the dynamical simulation shown what the Kepler-32 planetary system have likely to undergone a substantial inward migration in the past, producing an observed pattern of lower-mass planets on tightest orbits. Additional yet unobserved gas giant planets on wider orbit are likely necessary for migration of smaller planets to proceed that far inward, although current planetary system would be unstable if additional planets are located closer than 8.7 AU from the parent star.


NGC 6745

NGC 6745 (also known as UGC 11391) is an irregular galaxy about 206 million light-years (63.5 mega-parsecs) away in the constellation Lyra. It is actually a trio of galaxies in the process of colliding.
The three galaxies have been colliding for hundreds of millions of years. After passing through the larger galaxy (NGC 6745A), the smaller one (NGC 6745B) is now moving away. The larger galaxy was probably a spiral galaxy before the collision, but was damaged and now appears peculiar. It is unlikely that any stars in the two galaxies collided directly because of the vast distances between them. The gas, dust, and ambient magnetic fields of the galaxies, however, do interact directly in a collision. As a result of this interaction, the smaller galaxy has probably lost most of its interstellar medium to the larger one.


List of stars in Canis Major

This is the list of notable stars in the constellation Canis Major, sorted by decreasing brightness.


NGC 5609

 NGC 5609 is a spiral galaxy located 1.3 billion light-years light-years away from Earth, in the constellation Boötes. It has the second largest redshift of any galaxy in the New General Catalogue. Only NGC 1262, another spiral galaxy has a higher redshift. NGC 5609 was discovered by astronomer Bindon Blood Stoney on March 1, 1851.


Chi Ophiuchi

Chi Ophiuchi, Latinized from χ Ophiuchi, is a variable star in the equatorial constellation of Ophiuchus. It has a blue-white hue and is faintly visible to the naked eye with an apparent visual magnitude that fluctuates around 4.22. The distance to this object, as determined from parallax measurements, is approximately 530 light years, but it is moving closer to the Sun with a radial velocity of −19 km/s. This star is a proper motion member of the Upper Scorpius sub-group in the Scorpius-Centaurus OB association; the nearest such co-moving association of massive stars to the Sun.
This is a massive Be star with a stellar classification of B2Vne, where the 'n' indicates "nebulous" lines due to rapid rotation. It is spinning with a projected rotational velocity of 144 km/s. As the critical velocity for the star is 477 km/s, the inclination angle of its poles must be small; estimated as ~20°. It is a Gamma Cassiopeiae variable with an amplitude of 0.15 magnitude. The brightness has been measured varying from magnitude 4.18 down to 5.0.
Chi Ophiuchi is 22.5 million years old with 10.1 times the mass of the Sun. It has 12.6 times the Sun's radius and is radiating 245 times the luminosity of the Sun from its photosphere at an effective temperature of 6,432 K. A weak magnetic field has been detected in the chromosphere of this star. It is being orbited by a symmetrical disk of ejected gas extending out to , and excess radio and infrared emission has been detected from this structure.
Abt and Levy (1978) cataloged Chi Ophiuchi as a single-lined spectroscopic binary with a period of 138.8 days and an eccentricity of 0.44, although the orbital elements are considered marginal. Eggleton and Tokovinin (2008) list it as a single star.


25 Cancri

25 Cancri is a common proper motion star system in the zodiac constellation of Cancer, located around 348 light years away from the Sun. It has the Bayer designation d2 Cancri (d2 Cnc); "25 Cancri" (25 Cnc) is the Flamsteed designation. It is near the lower limit of visibility to the naked eye in good viewing conditions, appearing as a dim, yellow-white hued star with a combined apparent visual magnitude of 6.11. The pair have a relatively high proper motion, traversing the celestial sphere at an angular rate of per year. It is moving further from the Earth with a heliocentric radial velocity of +37 km/s.
Based upon a stellar classification of F6 V, the brighter component is an F-type main-sequence star that is generating energy through hydrogen fusion at its core. Cowley (1976) listed a class of F5 IIIm?, which suggests it may be an Am star. However, this has not been confirmed. It is about 2.5 billion years old with 1.51 times the mass of the Sun. The star is radiating 6.6 times the Sun's luminosity from its photosphere at an effective temperature of 6,487 K.
The companion is 4.19 magnitudes fainter than the primary, and lies at an angular separation of along a position angle of 310°, as of 2013. If the pair are gravitationally bound, then they orbit each other with a period of around .


NGC 459

NGC 459, also known as UGC 832, MCG 3-4-17, ZWG 459.24, and PGC 4665, is a spiral galaxy in the constellation Pisces. It was discovered on October 15, 1784, by William Herschel. It was described as being extremely faint by John Dreyer in the New General Catalogue.
NGC 459 (2MASS)


List of stars in Serpens

This is the list of notable stars in the constellation Serpens, sorted by decreasing brightness.


NGC 4036

NGC 4036 is the "New General Catalogue" identifier for a lenticular galaxy in the northern circumpolar constellation of Ursa Major. In the "Carnegie Atlas of Galaxies", it is described as being "characterized by an irregular
pattern of dust lanes threaded through the disc in an 'embryonic' spiral pattern indicating a mixed S0/Sa form." It is located near the Big Dipper, a little to the north of the mid-way point between the stars Alpha Ursae Majoris and Delta Ursae Majoris. With a visual magnitude of 10.7, it can be dimly viewed using a aperture telescope.
The visual dimensions of this galaxy are arc minutes, with the major axis having a position angle of 85°. The galaxy is being viewed nearly edge-on, with an inclination of 18° to the line of sight from the Earth. It is moving away from us with a radial velocity of . The estimated visual luminosity of the galaxy is  L⊙, or 42 billion times the brightness of the Sun. Photographs show a tightly wound spiral pattern in the galactic disk, with three dust lanes—the southern side of the galaxy appears dimmer due to the dust configuration. The mass of the free gas and dust in the galaxy is about  M⊙ and  M⊙, respectively, with around  M⊙ of the gas being in an ionized state.
This is a type of active galaxy known as a LINER, which means that it shows emission lines of ionized gas in the region of its nucleus. Chemically, the stars at the center of the nucleus have a higher metallicity than in the neighboring regions. It appears that there is a tilted disk of stars orbiting the nucleus within a radius of . The galactic bulge itself appears triaxial with the ionized gas concentrated near the center of this bulge region. Images of the galaxy with the Hubble Space Telescope show a wispy disk of dust on all sides of the nucleus, with what appears to be the tendrilous remains of an ionization cone leading away 4 arc seconds to the northeast. Such features are common in Seyfert galaxies.
On July 23, 2007, Type Ia supernova SN 2007gi was discovered by Koichi Itagaki near the central bulge of this galaxy. It reached peak magnitude around August 14, then steadily declined in brightness thereafter. Materials identified in the spectrum included silicon, calcium, and sulfur moving outward at velocities of around 15,500 km/s. This is a 50% higher velocity than what is normally observed with supernovae of this type.
NGC 4036 is a member of the LGG 266 galaxy group, along with NGC 4041, IC 758, UGC 7009, and UGC 7019. It is located just 17 arc minutes from NGC 4041, and the two form a pair with a projected separation of around .


NGC 7073

NGC 7073 is a spiral galaxy located about 230 million light-years away in the constellation of Capricornus. NGC 7073 was discovered by astronomer Albert Marth on August 25, 1864.


NGC 2782

NGC 2782 is a peculiar spiral galaxy that formed after a galaxy merger in the constellation Lynx. The galaxy lies 75 million light years away from Earth, which means, given its apparent dimensions, that NGC 2782 is approximately 100,000 light years across. NGC 2782 has an active galactic nucleus and it is a starburst and a type 1 Seyfert galaxy. NGC 2782 is mentioned in the Atlas of Peculiar Galaxies in the category galaxies with adjacent loops.
Structure.
Active galactic nucleus.
The nucleus and circumnuclear region of NGC 2782 display starburst activity, with bar of the galaxy providing gas to the nucleus. The active galactic nucleus is hidden by a compact high-column-density absorber and a H2O maser is associated with it. The vigorous star formation creates an unusual "superwind" of out-flowing gas, which has been detected in X-rays as a bubble like structure, approximately 7 arcsec south of the central region of the galaxy. A similar bubble can be seen in radiowaves at the north side. There is also diffuce X-rays emission. The nucleus of NGC 2782 is a low luminosity active galactic nucleus.
Tidal tails.
NGC 2782 shows two tidal tails, directing to opposing directions. As depicted in HI imaging, a plume extends about 5 arcmin toward the northwest, with estimated mass of atomic hydrogen, accounting for about 40 percent of the total HI mass of the system. A shorter HI plume extending toward the east has been associated with the stellar tail which extends 2.7 arcmin toward the east in the optical images. The northwest tail is fainter in the optical spectrum. CO was detected in the eastern tail, underlying the presence of molecular gas and HII regions in the region, with total mass or even more. There is starformation activity in the eastern tail. In the western tail have been detected 7 UV sources. These stellar populations are 1 to 11 million years old. Three of them have high metallicity, similar to that of the nucleus of the galaxy.
Ultraluminous X-ray sources.
Via observations by the Chandra X-ray Observatory, 27 X-ray point sources, of which 13 are ultraluminous X-ray sources (without counting the central one), were observed near the nucleus and are likely associated with the galaxy. This number is unusually high for a galaxy, although ultraluminous X-ray sources are common in starburst galaxies. Sixteen of these sources have a visual counterpart.
Nearby galaxies.
NGC 2782 is the largest galaxy in a small group of four galaxies. Nearby galaxies include UGC 4867 and UGC 4871 and further away lie NGC 2785 and UGC 4889.


UX Tauri

UX Tauri, abbreviated as UX Tau, is a binary star system approximately 450 light-years away in the constellation of Taurus (the Bull). It is notable for the fact that, despite its recent (in stellar terms) creation, the Spitzer Space Telescope discovered that its protoplanetary disk contains a gap. The dust, which normally accumulates in an expanding ring starting right next to the star at such a young age, is either very thin or nonexistent at a range of 0.2 to 56 AU from the star. Typically, this means that the early ancestors of planets may be forming from the disk, though the star only ignited about 1 million years ago. In contrast, Earth was formed approximately 4.54 billion years ago, placing its formation about sixty million years after the Sun's ignition around 4.6 billion years ago.


HD 34989

HD 34989 is a blue-white star in the main sequence, of apparent magnitude 5.80, in the constellation of Orion. It is 1700 light-years from the solar system.
Observation.
The star is in the northern celestial hemisphere, but close to the celestial equator; this means that it can be observed from all the inhabited regions of the Earth without difficulty and that it is not visible only in the innermost areas of Antarctica. It appears as circumpolar only far beyond the Arctic polar circle. Its brightness puts it at the limit of visibility to the naked eye, so to be observed without the aid of devices requires a clear, and preferably moonless, sky.
The best period for observation in the evening sky is between late October and April from both hemispheres; in February (as at J2000) it is anti-posed from the sun. In July and August its direction is close to that of the sun, therefore coinciding with most hours of daylight.
Physical characteristics.
It is a blue-white star of the main sequence, having an absolute magnitude of -0.99 and its positive radial velocity indicates that the star is moving away from the solar system.
The star appears wrapped in an extensive nebulosity that partly shines by reflection and partly by emission. The reflection nebula is listed as GN 05.19.0 and the HII region is called Sh2-263. HD 34989 is the ionizing source of this HII-region. In observations with carbon monoxide this corresponds to a circular hole.
The star has a size of about 0.118 ± 0.026 milliarcseconds, based on SED fitting.


HD 205739

HD 205739 is a yellow-white hued star in the southern constellation of Piscis Austrinus, positioned near the western constellation boundary with Microscopium. It has the proper name Sāmaya, which was selected in the NameExoWorlds campaign by Sri Lanka, during the 100th anniversary of the IAU. Sāmaya means peace in the Sinhalese language.
With an apparent visual magnitude of 8.56, this star requires a small telescope to view. It is located at a distance of approximately 302 light years from the Sun based on stellar parallax, and is drifting further away with a radial velocity of +9 km/s This star has an absolute magnitude of 3.42.
HD 205739 is an ordinary F-type main-sequence star with a stellar classification of F7 V. This indicates that, like the Sun, it is generating energy through core hydrogen fusion. The star is 2.8 billion years old with an inactive chromosphere and is spinning with a projected rotational velocity of 4 km/s. It has 1.3 times the mass of the Sun and 1.6 times the Sun's radius. The abundance of iron is 60% greater than in the Sun, suggesting a higher metallicity. The star is radiating 3.5 times the luminosity of the Sun from its photosphere at an effective temperature of 6,276 K.
A Jupiter-like planet has been detected in an eccentric orbit around this star via Doppler spectroscopy. The eccentricity of 0.27 indicates that the orbit carries the body from out to between periastron and apastron. The maximum surface temperature of the planet is ~400 K, varying by 100 K over the course of an orbit. There is a data trend in the results which may point to an additional companion further from its star, but this will require a longer observation period to validate.


Baby Boom Galaxy

The Baby Boom Galaxy is a starburst galaxy located 12.2 billion light years away. Discovered by NASA's Spitzer Science Center at the California Institute of Technology, the galaxy is the record holder for the brightest starburst galaxy in the very distant universe, with brightness being a measure of its extreme star-formation rate. The Baby Boom Galaxy has been nicknamed "the extreme stellar machine" because it is seen producing stars at a rate of up to 4,000 per year (one star every 2.2 hours). The Milky Way galaxy in which Earth resides turns out an average of just 10 stars per year.
Discovery.
The Baby Boom Galaxy was discovered and characterized in 2008 using a suite of telescopes operating at different wavelengths. NASA's Hubble Space Telescope and Japan's Subaru Telescope, atop Mauna Kea in Hawaii, first spotted the galaxy in visible-light images, where it appeared as an inconspicuous smudge due to its great distance. It wasn't until the Spitzer and the James Clerk Maxwell Telescope, also on Mauna Kea in Hawaii, observed the galaxy at infrared and submillimeter wavelengths, respectively, that the galaxy was formally discovered.
Strange behavior.
The Baby Boom Galaxy is so named because it generates over 4,000 stars per year (compared to an average of just 10 per year for the Milky Way). At that rate, the galaxy needs only 50 million years to create as many stars as the most massive galaxy ever observed. The discovery also challenges the accepted model for galaxy formation, which has most galaxies slowly bulking up by absorbing pieces of other galaxies, rather than growing internally. Another unusual aspect is the fact that scientists are observing this galaxy at a time when the universe was only a little over 1.4 billion years old, meaning that this galaxy was exhibiting this strange behaviour while the universe was still in its infancy.
"This galaxy is undergoing a major baby boom, producing most of its stars all at once," said Peter Capak of NASA's Spitzer Science Center at the California Institute of Technology. "If our human population was produced in a similar boom, then almost all of the people alive today would be the same age."
To that, the principal investigator of the Cosmic Evolution Surveyor, Nick Scoville of Caltech responded:
"We may be witnessing, for the first time, the formation of one of the most massive elliptical galaxies in the universe."
Colors.
The red color on the galaxy represent the birth of new stars. The color green represents a denoted gas, while the blue shows other galaxies that are less active in producing stars.
References.
[Baby Boomer Galaxy Found - Universe Today. (2008, July 10).|http://www.universetoday.com/15492/baby-boomer-galaxy-found/]
Ancient Galaxy Fires Out New Stars at Record Pace. (n.d.). Retrieved
Baby Boom: Ancient Galaxy Fires Out New Stars at Record Pace. (n.d.).


FN Canis Majoris

FN Canis Majoris is a binary star system in the southern constellation Canis Major, near the northern constellation border with Monoceros. It is dimly visible to the naked eye with a combined apparent visual magnitude of 5.41. The system is located at a distance of approximately 3,000 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +31 km/s. It is a runaway star associated with the Sh 2-296 nebula in the CMa OB1 association, and has a conspicuous bow-shock feature.
The brighter component is a visual magnitude 5.69 B-type star that has been assigned various stellar classification from B0 III/IV to B2 Ia/ab, suggesting it is an evolved state. In the past it was classified as a Beta Cephei type variable star with an apparent magnitude that was measured varing between +5.38 and +5.42 over a period of 36.7 hours, but is no longer considered to be one. This is a massive star with estimates ranging from 19 to 36 times the mass of the Sun, and luminosity estimates of 122,079 to 690,000 times the Sun's luminosity. The magnitude 7.04 companion is located at an angular separation of from the primary at a position angle of 111°, as of 2003.


HIP 70849 b

HIP 70849 b is an extrasolar planet which orbits the K-type main sequence star HIP 70849, located approximately 78 light years away in the constellation Lupus. This planet has more than five times the mass of Jupiter and takes more than 3000 days to orbit the star at a semimajor axis of more than 3.5 AU. However unlike most other known exoplanets, its eccentricity is not known, but it is typical that its inclination is not known. This planet was detected by HARPS on October 19, 2009, together with 29 other planets.


NGC 5395

NGC 5395 is an interacting spiral galaxy located at a distance of 160 million light years, but receding away from the earth at 3511 kilometers (2181.6 miles) per second, in the constellation Canes Venatici. It was discovered by William Herschel on May 16, 1787. NGC 5395 and NGC 5394 are included in the Atlas of Peculiar Galaxies as Arp 84 in the category "Spiral galaxies with large high surface brightness companions".
NGC 5395 is the larger spiral galaxy interacting with smaller barred spiral galaxy, NGC 5394. NGC 5395 is nearly face-on, with a diameter of around 140,000 light-years across. NGC 5395 has a bright central region and is distorted due to the interaction with NGC 5394. The larger of the two rings around the galaxy forms a ring off the center of the galaxy. Dust lanes can be seen throughout the galaxy.
NGC 5394 is the smaller barred spiral galaxy interacting with larger spiral galaxy, NGC 5395. NGC 5394 has an oval disk, with a diameter of around 90 thousand light years across. It is also located at a distance of 160 million light-years across but receding away from the earth at a distance of 3448 kilometers (2142.4 miles) per second. Most of the gas is concentrated at the center of the galaxy, however, two out of the three spiral arms show no sign of ongoing star formation.
NGC 5395 is a Seyfert 2 galaxy.
Supernova.
One supernova has been detected in NGC 5395, Type Ic supernova SN 2000cr. It was discovered on June 25.90 and 25.94 (UTC) at magnitude 17.0 lying northeast of the nucleus.


List of stars in Aquila

This is the list of 143 notable stars in the constellation Aquila, sorted by decreasing brightness.


42 Cassiopeiae

42 Cassiopeiae is a possible binary star system in the northern circumpolar constellation of Cassiopeia. It is visible to the naked eye as a dim, blue-white hued star with a baseline apparent visual magnitude of +5.18. The system is located approximately 291 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +7 km/s.
This is classified as a suspected eclipsing binary of the Algol type, with a period of 16.77 days and a magnitude decrease of 0.3. The primary is a B-type main-sequence star with a stellar classification of B9V. It is roughly 67 million years old and is spinning with a projected rotational velocity of 149 km/s. The star has 2.7 times the mass of the Sun and 2.6 times the Sun's radius. It is radiating 66 times the luminosity of the Sun from its photosphere at an effective temperature of 10,141 K.


Ox (Chinese constellation)

The Ox mansion (牛宿, pinyin: Niú Xiù) is one of the Twenty-eight mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise. The primary asterism of this mansion is centered on the tail of the constellation known as Capricornus in Western astronomy.


Nu Octantis

ν Octantis, Latinised as Nu Octantis, is a spectroscopic binary star in the constellation Octans with a period around 2.9 years. Its apparent magnitude is 3.73. Located around distant, the primary is an orange giant of spectral type K1III, a star that has used up its core hydrogen and has expanded. The secondary star is likely either a red dwarf or a white dwarf, from its relatively low mass.
Planetary system.
In 2009, the system was hypothesised to contain a superjovian exoplanet based on perturbations in the orbital period. A prograde solution was quickly ruled out but a retrograde solution remains a possibility, although the variations may instead be due to the secondary star being itself a close binary, since the formation of a planet in such a system would difficult due to dynamic perturbations. Further evidence ruling out a stellar variability and favouring the existence of the planet was gathered by 2021.


Wings (Chinese constellation)

The Wings mansion (翼宿, pinyin: Yì Xiù) is one of the Twenty-eight mansions of the Chinese constellations. It is one of the southern mansions of the Vermilion Bird.


A Carinae

The Bayer designations A Carinae and a Carinae are distinct. Due to technical limitations, both designations link here. For the star


46 Capricorni

46 Capricorni is a solitary star located around 790 light years away from the Sun in the southern constellation of Capricornus, near the northern border with Aquarius. It is visible to the naked eye as a dim, yellow-hued point of light with an apparent visual magnitude of +5.10. 46 Cap is also known by its Bayer designation of c Capricorni (c Cap), and occasionally as c1 Capricorni to distinguish it from the nearby star c2 Capricorni. It is moving closer to the Earth with a heliocentric radial velocity of −15.5 km/s.
This star has received a stellar classification of G8Iab, which suggests it is a G-type supergiant star, as well as G7.5II-IIICN0.5, which instead indicates a luminosity class between a giant and a bright giant. Abundance analysis suggests the star has not yet passed the first dredge-up. It has 4.6 times the mass of the Sun and has expanded to 33 times the Sun's radius. The star is radiating 627 times the luminosity of the Sun from its photosphere at an effective temperature of 4,837 K.
Etymology.
This star, along with β Aqr (Sadalsuud) and ξ Aqr (Bunda), were Saʽd al Suʽud (سعد السعود), the Luck of Lucks.


NGC 2798

NGC 2798 is a barred spiral galaxy in the constellation Lynx. NGC 2798 and NGC 2799 are listed under the Arp Catalogue as Arp 283 and noted as an "interacting galaxy pair". The galaxy is listed in the New General Catalogue.


25 Orionis

25 Orionis, less commonly known by its Bayer designation Psi1 Orionis (ψ1 Orionis, ψ1 Ori) is a fifth-magnitude star in the constellation Orion. It lies among a dense cluster of low-mass pre-main-sequence stars in the Orion OB1a.
Stellar group.
25 Orionis is the dominant member of a rich low-mass star region, first identified in 2005 in a statistical analysis of 2.5 million star. It is one of several sub-associations within Orion OB1a, all thought to lie at around the same distance of 338 parsecs. Over 200 members of the 25 Orionis stellar group have been found, mostly T Tauri stars with spectral types of K and M and masses less than half the sun's. There are also around 60 hotter stars in the region, including the eruptive variable V346 Tauri.
Properties.
Like the star Pleione in the Pleiades open cluster, 25 Ori is a Be star with a gaseous circumstellar disk. The SIMBAD astronomical database lists its spectral class as B1Vn.
25 Orionis is a fast rotator, clocking a rotational velocity of 316 km/s, significantly faster than Achernar's speed of 251 km/s in the constellation Eridanus. Having a radius of , the star rotates on its axis roughly once every 23 hours. With a mass in excess of , the star is expected to explode as a supernova.


Rho Draconis

Rho Draconis (ρ Draconis) is a solitary star in the northern circumpolar constellation of Draco. It is faintly visible to the naked eye with an apparent visual magnitude is 4.52. Based upon an annual parallax shift of 7.61 mas as measured from Earth, it is located around 429 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.027 due to interstellar dust.
With a stellar classification of K3 III, Rho Draconis is a normal giant star that is past the first dredge-up phase of its post-main sequence evolution. It has the peculiar spectrum of a CN star, showing abnormal line strengths for cyanogen and calcium. The star has expanded to around 28 times the Sun's radius and it is radiating 402 times the solar luminosity from its photosphere at an effective temperature of 4,370 K.


88 Tauri

88 Tauri, also known as d Tauri, is a multiple star system in the constellation Taurus. It has an apparent magnitude of about 4.25, meaning that it is visible to the naked eye. Based upon parallax measurements made by the Hipparcos spacecraft, the star system is some from the Sun.
88 Tauri is a sextuple star system, meaning that it contains six stars in a hierarchical orbit. The brighter component, 88 Tauri A, is a quadruple system consisting of two spectroscopic binaries orbiting each other with an orbital period of 18 years. The fainter component, 88 Tauri B, is also a spectroscopic binary, and is about 69 arcseconds away, bringing up the total to six stars.
Orbit.
Hierarchy of orbits in the 88 Tauri system
88 Tauri A is a fourth-magnitude star with two components, 88 Tauri Aa and 88 Tauri Ab. 88 Tauri Aa and Ab orbit each other once every 18 years and are separated by about 0.28 arcseconds. Those two components themselves are spectroscopic binaries: binary stars that are too close to be resolved but can be detected by periodic Doppler shifts in their spectrum. In this case, variability in the radial velocity has been recognized as early as 1907. The Aa pair has an orbital period of 3.57 days, the Ab pair has an orbital period of 7.89 days, and both have circular orbits with low orbital eccentricities.
88 Tauri B, 69.56 arcseconds away, is a seventh-magnitude star that is also a binary star system. It is another spectroscopic binary whose components (88 Tauri Ba and Bb) orbit each other every 3.69 years. The orbit of 88 Tauri B around 88 Tauri A likely takes about 70,000 years.
Properties.
88 Tauri Aa has a spectral type of A6m, indicating that it is an A-type star. The "m" in its spectral type means that it is an Am star, also known as a metallic-line star. These types of stars have spectra indicating varying amounts of metals, like iron. The rest of the stars in 88 Tauri A have spectral types ranging from F5 to G2-3, meaning that they are regular F-type or G-type main-sequence stars. The spectral types for 88 Tauri Ab1 and Ab2 are less certain, because their spectral lines are weaker, hence the colon after G2. Aa1 does not appears to be rotating synchronously with its companion (nor does it have a convective atmosphere), unlike Aa2. (It is not known if the two stars of 88 Tauri Ab are in synchronous rotation with each other, because of the relatively high errors in their measurements.)
88 Tauri B consists of a F-type main sequence star, with another low-mass star. The mass of the smaller component is at least 0.15 solar masses, so it is most likely a red dwarf.


NGC 467

NGC 467 is an unbarred lenticular galaxy in the constellation Pisces. It was discovered on 8 October 1785 by William Herschel.


Gamma2 Normae

Gamma2 Normae, Latinized from γ2 Nor, is the brightest star in the southern constellation of Norma. Its apparent magnitude is 4.02 – making it a faint star but visible to the naked eye. Based upon an annual parallax shift of 25.33 mas as seen from Earth, this star is located roughly 129 light years from the Sun. It is moving closer to the Sun with a radial velocity of −29 km/s.
This is an evolved, yellow-hued giant of spectral type K0 III around 2.16 times as massive as the Sun that has swollen to a diameter 10 times that of the Sun. It is a red clump star on the horizontal branch, which indicates it is generating energy through helium fusion at its core. The star is radiating 51 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,699 K.
Gamma2 Normae is a close double, with a magnitude 10 companion. The pair has been previously identified as a binary star system, but the second release of Gaia data showed the companion star to be much more distant. Another 16-magnitude star, with a temperature of , is listed 20" away with nearly the same parallax and proper motion as Gamma2 Normae.
γ1 Nor is a yellow supergiant located nearby on the celestial sphere, but is much further away from Earth and nearly a magnitude fainter.


HD 29697

HD 29697 (Gliese 174, V834 Tauri) is a variable star of BY Draconis type in the constellation Taurus. It has an apparent magnitude around 8 and is approximately 43 ly away.
Description.
HD 29697 is the Henry Draper Catalogue number of this star. It is also known by its designation in the Gliese Catalogue of Nearby Stars, Gliese 174, and its variable star designation V834 Tauri.
V834 Tauri is a BY Draconis variable with maximum and minium apparent magnitudes of 7.94 and 8.33 respectively, so it is never visible to the naked eye.
The star has been examined for indications of a circumstellar disk using the Spitzer Space Telescope, but no statistically-significant infrared excess was detected.


NGC 6300

NGC 6300 is a barred Seyfert spiral galaxy located in the constellation Ara. It is classified as SB(rs)b in the galaxy morphological classification scheme and was discovered by the Scottish astronomer James Dunlop on 30 June 1826. NGC 6300 is located at about 51 million light years away from Earth. It is suspected that a massive black hole (300,000 times the mass of Sun) may be at its center, pulling all the nearby objects into it. In turn, it emits large amounts of X-rays.<ref name="NASA/IPAC"></ref><ref name="The NGC/IC Project"></ref>


Kappa Scorpii

Kappa Scorpii, Latinized from κ Scorpii, is a binary star system in the southern constellation of Scorpius. With an apparent visual magnitude of 2.4, this star system is readily visible to the naked eye. Parallax measurements place it at an estimated distance of roughly from the Earth.
Properties.
This is a spectroscopic binary, which is a type of binary star system in which the two stars are so close together that they have not been individually resolved with a telescope. The pair orbit each other with a period of about 196 days and an eccentricity of nearly 0.5. The combined spectrum of this pair matches a star with a stellar classification of B1.5 III. The 'III' luminosity class indicates the presence of a giant star that has exhausted the supply of hydrogen at its core and is in a late evolutionary stage.
The primary component of the pair, κ Sco A, is a variable star of Beta Cephei type. It is undergoing radial pulsations with a dominant frequency of 4.99922 cycles per day, or 4.8 hours per cycle. There are overlapping secondary pulsation frequencies of about 4.85 and 5.69 cycles per day. This star has about 17 times the mass of the Sun and is nearly 7 times the Sun's radius. The effective temperature of the outer envelope is 23,400 K, giving it a blue-white hue. It is rotating rapidly, with an estimated period of only 1.9 days and an axis of rotation that is inclined by about 40° to the line of sight from the Earth.
The secondary component, κ Sco B, is smaller than the primary, but still much larger than the Sun. It has about 12 times the mass of the Sun and nearly six times the Sun's radius. The effective temperature of 18,800 K is also higher than the Sun's, which is at 5,778 K.
Traditional name.
κ Scorpii has been called Girtab , which is the Sumerian word for 'scorpion'. The name has survived through the Babylonian star catalogues, and was originally applied to an asterism comprising this star, Lambda Scorpii, Upsilon Scorpii, and Iota Scorpii.
In Chinese, (), meaning "Tail", refers to an asterism consisting κ Scorpii, μ1 Scorpii, ε Scorpii, ζ1 Scorpii and ζ2 Scorpii, η Scorpii, θ Scorpii, ι1 Scorpii and ι2 Scorpii, λ Scorpii and υ Scorpii. Consequently, the Chinese name for κ Scorpii itself is (), "the Seventh Star of Tail".
Modern legacy.
κ Scorpii appears on the flag of Brazil, symbolising the state of Paraíba.


NGC 5307

NGC 5307 is a planetary nebula in the southern constellation of Centaurus, positioned less than 3° to the northeast of the star Epsilon Centauri. It was discovered by English astronomer John Herschel on April 15, 1836. The nebula is located at a distance of approximately from the Sun. The central star, designated PNG 312.3+10.5, is a weak emission-line star, superficially similar to the WC subtype of Wolf–Rayet stars. It has a spectral class of O(H)3.5 V.
This is a Type IIb/III planetary nebula with a low expansion velocity of . The chemical abundances in the shell indicate that the progenitor had only undergone partial conversion of carbon into nitrogen when its life span came to an end. The morphology shows point symmetry around the center. Overall it is rectangular in shape, and has two pairs of higher density knots that are symmetric around the middle, aligned along position angles of approximately 30° and 163°. These display a slightly enhanced abundance of nitrogen compared to the rest of the nebula and are photoionized on the side facing the central star. The symmetrical shape of the nebula may have arisen from jets emerging from both sides of a disk about the central star.


Delta Crateris

Delta Crateris (δ Crt, δ Crateris; traditional name: Labrum) is a solitary star in the southern constellation of Crater. With an apparent visual magnitude of 3.56, it is the brightest star in this rather dim constellation. It has an annual parallax shift of 17.56 mas as measured from Earth, indicating Delta Crateris lies at a distance of 163 ± 4 light years from the Sun.
This is an evolved orange-hued giant star belonging to the spectral class K0 III. Delta Crateris is a member of the so-called red clump, indicating that it is generating energy through the thermonuclear fusion of helium at its core. The star has an estimated 1.56 times the mass of the Sun but has expanded to times the Sun's radius.
The metallicity of the star – what astronomers term the abundance of elements other than hydrogen and helium – is only 33% that of the Sun. It is around 2.89 billion years old with a rotation rate that is too small to measure; the projected rotational velocity is 0.0 km/s. Delta Crateris is radiating as much luminosity as the Sun from its outer envelope at an effective temperature of  K.


Upsilon2 Hydrae

Upsilon2 Hydrae, Latinized from υ2 Hydrae, is a solitary star in the equatorial constellation of Hydra. Visible to the naked eye, it is photometrically stable with an apparent visual magnitude of 4.59. Based upon an annual parallax shift of 10.40 mas as seen from Earth, it is located about 314 light years from the Sun.
This is a B-type star with a stellar classification of B9 III-IV, showing partial traits of a subgiant and giant star in its spectrum. However, Zorec and Royer (2012) estimate the star still only 79% of the way through its life span on the main sequence. With an age of around 97 million years, it is spinning with a projected rotational velocity of 58 km/s. The star has an estimated 3.29 times the mass of the Sun and around 3.2 times the Sun's radius. It is radiating 182 times the solar luminosity from its photosphere at an effective temperature of about 11,758 K.


NGC 6452

NGC 6452, also occasionally referred to as PGC 60876 or GC 5878, is a lenticular galaxy in the constellation Hercules. It was discovered on 2 July 1864 by astronomer Albert Marth.


AH Velorum

AH Velorum is a single, yellow-white hued star in the constellation Vela. It has an average apparent visual magnitude of 5.70, which makes it bright enough to be dimly visible to the naked eye in good seeing conditions. The distance to this star can be estimated from its annual parallax shift of , which yields a separation of roughly 2,700 light years. It is moving further away from the Earth with a heliocentric radial velocity of +26 km/s.
It is a bright giant/supergiant of spectral type F7 Ib-II. The star is around 50 million years old with a projected rotational velocity of 10 km/s. It has 7 times the mass of the Sun and is radiating 930 times the Sun's luminosity from its photosphere at an effective temperature of 6,102 K.
A classical Cepheid variable, its apparent magnitude ranges from 5.50 to 5.89 over 4.227171 days. It pulsates in the first overtone, with a fundamental period of 6.04 days.


Nu Sagittarii

The Bayer designation Nu Sagittarii (Nu Sgr, ν Sagittarii, ν Sgr) is shared by two star systems, ν1 Sagittarii and ν2 Sagittarii, in the zodiac constellation Sagittarius. The two stars are separated by 0.23° in the sky.
Nu Sagittarii has the traditional name Ain al Rami, which is from the Arabic عين الرامي "cain ar-rāmī" meaning "eye of the archer". Both of the ν stars, together with τ Sgr, ψ Sgr, ω Sgr, 60 Sgr and ζ Sgr were "Al Udḥiyy", the Ostrich's Nest. Nu Sagittarii is often cited as one of the earliest identified double stars. In the Almagest, Ptolemy describes the star as "nebulous and double", referring to the double nature of the star.


RR Coronae Borealis

RR Coronae Borealis (RR CrB, HD 140297, HIP 76844) is a M3-type semiregular variable star located in the constellation Corona Borealis with a parallax of 2.93mas being a distance of . It varies between magnitudes 7.3 and 8.2 over 60.8 days. Located around 1228 light-years distant, it shines with a luminosity approximately 2180 times that of the Sun and has a surface temperature of 3309 K.


Lambda Serpentis

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Lambda Serpentis (λ Ser, λ Serpentis) is a star in the constellation Serpens, in its head (Serpens Caput). It has an apparent visual magnitude of 4.43, making it visible to the naked eye. Based upon parallax measurements from the Hipparcos satellite, this star lies at a distance of about from Earth. This star is larger and more massive than the Sun, although it has a similar stellar classification. It is shining with nearly double the Sun's luminosity and this energy is being radiated from the star's outer atmosphere at an effective temperature of 5,884 K.
Lambda Serpentis is moving toward the Solar System with a radial velocity of 66.4 km s−1. In about 166,000 years, this system will make its closest approach of the Sun at a distance of , before moving away thereafter.
A periodicity of 1837 days (5.03 years) was suspected by Morbey & Griffith (1987), but it is probably bound to stellar activity. However, McDonald Observatory team has set limits to the presence of one or more exoplanets around Lambda Serpentis with masses between 0.16 and 2 Jupiter masses and average separations spanning between 0.05 and 5.2 Astronomical Units. In 2020, a candidate planet was detected orbiting Lambda Serpentis (HD 141004). With a minimum mass of 0.043 (13.6 ) and an orbital period of 15 days, this would most likely be a hot Neptune.


Zeta Piscis Austrini

Zeta Piscis Austrini (ζ Piscis Austrini) is an orange-hued star in the southern constellation of Piscis Austrinus. It has an apparent visual magnitude of +6.43, which is near the lower limit of stars that can be seen with the naked eye. Based upon an annual parallax shift of 7.55 mas as seen from the Gaia telescope, the star is located 413 ± 2 light years from the Sun. This is an evolved K-type giant star with a stellar classification of K1 III. It is a suspected variable star.


List of stars in Mensa

This is the list of notable stars in the constellation Mensa, sorted by decreasing brightness.


HD 205739 b

HD 205739 b is an extrasolar planet located approximately 350 light-years away
The planet HD 205739 b is named Samagiya. The name was selected in the NameExoWorlds campaign by Sri Lanka, during the 100th anniversary of the IAU. Samagiya means togetherness and unity in the Sinhalese language.
Discovery.
HD 205739's designation is from the Henry Draper catalogue. The star was also observed by "Hipparcos", which released its catalogue in 1997. The observations that led to the discovery of the planet HD 205739 b started when the N2K Consortium started an extended search for planets around 300 stars not usually targeted by Doppler spectroscopy surveys. In the case of HD 205739, the star was observed using the Magellan Telescopes at Las Campanas Observatory in Chile. HD 205739 was selected primarily because it was a metal-rich star; the N2K collaboration biased their search towards metal-rich stars with closely orbiting Jupiter-size planets, hoping to find a connection between a star's metallicity and its planets' masses.
HD 205739 was flagged originally as a candidate hosting a Hot Jupiter, which is a large gas giant that orbits closely to its star, although later observations suggested that the planetary candidate orbited further out over the next 3.5 years of observation.
The star was studied through the Magellan Inamori Kyocera Echelle spectrograph's (MIKE) ability to use Doppler spectroscopy to measure radial velocity. Twenty-four measurements were recorded for HD 205739. The measurements were analyzed for accuracy. They were then used to derive the planet's characteristics, which led to the planet's confirmation.
The team of astronomers, which were from the United States, Chile, and the Vatican City, sent the paper to the "Astronomical Journal" on April 7, 2008. The paper was accepted, and was later published on October 7, 2008.
Host star.
HD 205739 is an F-type star with a mass that is 1.22 times the mass of the Sun and a size that is 1.33 times the radius of the Sun. In other words, it is slightly more massive and slightly larger than the Sun is. With an effective temperature of 6176 K, HD 205739 is also hotter than the Sun, although it is younger, at an estimated age of 2.84 billion years. The star is rich in iron; its measured metallicity is [Fe/H] = 0.19, or 1.55 times the iron detected in the Sun. After analysis of HD 205739's spectrum, it can be concluded that HD 205739's chromosphere (its outermost layer) is not active. HD 205739 cannot be seen from Earth with the naked eye because the star has an apparent magnitude (V) of 8.56.
Characteristics.
HD 205739 b is a Jupiter-size planet. The estimated minimum mass is 1.37 times the mass of Jupiter. The planet has been found to orbit its host star every 279.8 days at a distance of 0.896 AU, which is approximately 89.6% of the mean distance between the Sun and the Earth. HD 205739 b has a mildly elliptical orbit, given its orbital eccentricity of 0.27. The planet's elliptical orbit is typical with respect to discovered planets whose orbits are longer than twenty days and have not grown circular because of tidal forces. According to its discoverers, HD 205739 b's elongated orbit causes its surface temperature to fluctuate by up to 100 K.


NGC 6380

NGC 6380 is a globular cluster located in the constellation Scorpius. It was discovered by the British astronomer John Herschel on 29 June 1834. It is at a distance of about 35,500 light years away from earth. NGC 6380 was initially characterized as an open cluster, and given the designation Pişmiş 25, however later in 1950, the American astronomer A. David Thackeray found that it is actually a globular cluster.


HD 78004

HD 78004 is a single star in the constellation Vela. It has the Bayer designation c Velorum, while "HD 78004" is the identifier from the "Henry Draper catalogue". The object has an orange hue and is visible to the naked eye with an apparent visual magnitude of 3.75. It is located at a distance of approximately 320 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +24 km/s.
This is an aging K-type giant star with a stellar classification of K2III, having exhausted the supply of hydrogen at its core then cooled and expanded off the main sequence. At present, it has 27 times the radius of the Sun. The star is radiating 271.5 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,483 K.


Sigma Capricorni

Sigma Capricorni, Latinized from σ Capricorni, is a solitary star in the southern constellation of Capricornus, 0.5 degree north of the ecliptic. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of +5.31. The star is about 1,070 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −9.6 km/s.
This object is an evolved, K-type giant star with a stellar classification of K2 III. Having exhausted the supply of hydrogen at its core, it has expanded and now has around 67.5 times the girth of the Sun. The star is about 60.5 million years old with 6.3 times the mass of the Sun. It is radiating 1,392 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,292 K.
A magnitude 9.43 visual companion is at an angular separation of along a position angle of 179°, as of 2016.


II Pegasi

II Pegasi is a binary star system in the constellation of Pegasus with an apparent magnitude of 7.4 and a distance of 130 light years. It is a very active RS Canum Venaticorum variable (RS CVn), a close binary system with active starspots.
The primary (II Pegasi A) is a cool subgiant, an orange K-type star. It has begun to evolve off the main sequence and expand. Starspots cover about 40% of its surface. The star produces intense flares observable at all wavelengths.
Its smaller companion (II Pegasi B) is too close to have been observed directly. It is a red dwarf, an M-type main sequence star. The stars are tidally locked in a very close orbit with a period of 6.7 days and a separation of a few stellar radii.
X-ray flares from II Pegasi A were observed with the Ariel 5 satellite in the 1970s and with later x-ray observatories. In December 2005 a superflare was detected by the Swift Gamma-Ray Burst Mission. It was the largest stellar flare ever seen and was a hundred million times more energetic than The Sun's typical solar flare.


Epsilon Equulei

Epsilon Equulei, Latinized from ε Equulei, is a star system of apparent magnitude +5.23 in the constellation of Equuleus. It is located 180 light years away from the Solar System, based on its parallax.
Star system.
Two stars make up the brighter part of the Epsilon Equulei star system. They are called Epsilon Equulei A and B and are main-sequence stars of spectral type of F5 and F6, respectively. The orbital period of this binary is about 101.5 years. Although the average separation between the two stars is about , the orbit is remarkably eccentric, at 0.705. The two stars passed their periastron in 1920. Finally, it is thought that Epsilon Equulei A may be, in turn, a spectroscopic binary. The orbital period of the latter would be 2.03133 days.
Approximately 10 arcseconds away from A and B is Epsilon Equulei C (HIP 103571), with an apparent magnitude of 7.35. It is another F-type main-sequence stars, and based on its similar distance and proper motion to A and B, it is assumed to be associated.
The Epsilon Equulei system is thought to be approximately 1.5 billion years old.


Pi2 Pegasi

π2 Pegasi, Latinized as Pi2 Pegasi, is a single star in the northern constellation Pegasus. It is yellow-white in hue and visible to the naked eye as a faint point of light with an apparent visual magnitude of +4.28. The distance to this object is approximately 263 light years based on parallax, and it is drifting further away with a radial velocity of +5 km/s. This star is an outlying member of the Ursa Major Moving Group.
This object has a stellar classification of F5 III, matching an aging giant star that has exhausted the supply of hydrogen at its core then cooled and expanded off the main sequence. At present it has 8.5 times the radius of the Sun. The star is 530 million years old with 2.48 times the Sun's mass. It shows a high rotation rate considering its evolutionary status, with a projected rotational velocity of 140 km/s. The star has been noted as a possible variable shell star. Pi2 Pegasi is radiating 103 times the Sun's luminosity from its swollen photosphere at an effective temperature of 6,300 K.


Apep (star system)

Apep is a triple star system containing a Wolf–Rayet binary and a hot supergiant, located in the constellation of Norma. Named after the serpent deity from Egyptian mythology, the star system is surrounded by a vast complex of stellar wind and cosmic dust thrown into space by the high rotation speed of the binary's primary star and formed into a "pinwheel" shape by the secondary star's influence. Ground-based studies of the system in the 2010s concluded that the system was the best known gamma-ray burst progenitor candidate in the Milky Way galaxy.
Nomenclature.
Apep, pronounced , was named by a team of astronomers led by Joseph Callingham of ASTRON, who studied the system between 2016 and 2018 and published a scientific paper on their observations. It was named after the eponymous mortal enemy of the deity of the sun Ra in Egyptian mythology, who was often illustrated as a giant serpent; their rivalry was described as "an apt allusion" to the appearance of the system and its stellar wind in infrared as "a star embattled within a dragon’s coils". In the XMM-"Newton" Serendipitous Source Catalogue (2XMM), a star catalog of X-ray sources observed by the XMM-"Newton" space telescope, the system is catalogued as 2XMM J160050.7–514245.
Characteristics.
Apep is a triple star system containing a Wolf–Rayet binary described as the "central engine", orbiting with a period of ~100 years, and a third hot supergiant star described as the "northern companion", orbiting the central engine at a distance of ~1,700 astronomical units and a period of >10,000 years. The binary at the centre of Apep is composed of two classical Wolf-Rayet stars of carbon- (WC8) and nitrogen-sequence (WN4-6b) subtypes, making Apep the strongest case of a classical WR+WR binary system in the Milky Way. Carbon-sequence Wolf-Rayet stars are often dust-making factories. A vast complex of stellar wind and cosmic dust surrounds the system, resembling WR 104, another Wolf-Rayet star system producing a pinwheel nebula. The wind, travelling at a velocity of , and dust travelling at at the edge of the system, suggest that at least one component of the central engine is rapidly rotating, in which its surface gravity is close to being balanced by its centrifugal force outwards. This component produces faster stellar winds from its poles and slower winds from its equator, and the equatorial wind's interaction with the wind of its secondary produces the system's "pinwheel" shape. Rapidly-rotating Wolf–Rayet stars are theoretically capable of producing a gamma-ray burst during a supernova, and the system has been identified as a progenitor for a gamma-ray burst. Apep is estimated to be at a distance of ~2.4 kiloparsecs, or ~8,000 light years, from Earth, with a potential discrepancy of +0.2 and −0.5 kiloparsecs at its estimated visual extinction of 11.4.
Observation.
Apep is located in the constellation of Norma, at a right ascension of and declination of , The system can be resolved into two components, the "central engine" Wolf–Rayet binary, and the "northern companion" supergiant. The total apparent magnitude of the system is 17.5, with the apparent magnitude of a resolved central engine and northern companion being 19.0 and 17.8 respectively. Its infrared spectral energy distribution (SED) is unique, with brightness ranging from an apparent magnitude of 6.4 at 2.2 µm to −2.4 at 22 µm. Surveys conducted with the European Southern Observatory (ESO)'s SINFONI instrument on the Very Large Telescope measured the apparent magnitude in the infrared J band for the central engine as , and for the northern companion as . SINFONI also measured the apparent magnitude of the system in the K band as for the central engine and for C, in the L band as for the central engine and for the northern companion, and in the M band as for the central engine and for the northern companion. SINFONI observations further detailed that the northern companion is possibly a conventional B1Ia+ high luminosity star. A and B show a typical spectrum from a WC7 star, but with additional WN4 or WN5 star features theorised to be from one of the stars of the central engine; if confirmed, this would make Apep a rare binary system of WR stars. An alternative hypothesis also based on SINFONI data proposes that the spectra could all be from an unusual transitional WN/WC star, and that the northern companion would then be a conventional OB star.
The system was the first gamma-ray burst progenitor candidate to be discovered in the Milky Way galaxy, although it had not been known as such in early observations, such as those with the XMM-"Newton" and "Chandra" space telescopes, where it had been identified simply as an X-ray source as early as August 2004. Astronomer Joe Callingham first observed Apep during undergraduate studies at the University of Sydney with the Molonglo Observatory Synthesis Telescope, and was noted as a potential colliding-wind binary, with a radio source as bright as Eta Carinae. Callingham and Peter Tuthill, who assisted in the discovery of WR 104 in 1998 and sought interest in Apep after observing its extreme infrared properties, used the ESO's Very Large Telescope for observations in August 2016. Further observations with the Anglo-Australian Telescope and the Australia Telescope Compact Array, along with contributions from various international institutions, led to the publication of a scientific paper in "Nature Astronomy" on 19 November 2018. It concluded that the system was a Wolf–Rayet binary and a progenitor for a gamma-ray burst. It had been previously assumed that such systems were only found in galaxies younger than the Milky Way.
References.
Notes
Sources
Citations


NGC 3223

NGC 3223 is a faint spiral galaxy in the constellation Antlia. It was discovered on February 2, 1835 by the astronomer John Herschel.


NGC 6528

NGC 6528 is a globular cluster in the constellation Sagittarius, and is listed in the New General Catalogue. It has an apparent magnitude of about 11 and a diameter of about 16 arcminutes, and its Shapley-Sawyer Concentration Class is V, containing stars of 16th magnitude and dimmer. Dreyer described it as "pF, cS, R", meaning poor and faint, considerably small and round.
NGC 6528 is located southwest of NGC 6522, another globular cluster. Both are located in Baade's Window, a relatively clear area near the galactic equator.
The globular cluster was discovered in 1784 by the astronomer William Herschel with his 18-inch telescopes.
The NGC 6528 is unusually metal-rich for a globular cluster, and is very similar in composition to NGC 6553, suggesting an origin in similar environment.


Eta Pictoris

The Bayer designation η Pictoris (Eta Pictoris) is shared by two stars, in the constellation Pictor:


Gamma Pictoris

Gamma Pictoris, Latinized from γ Pictoris, is a single, orange-hued star in the southern constellation of Pictor. It is a faintly visible to the naked eye with an apparent visual magnitude of 4.50. Based upon an annual parallax shift of 18.45 mas as seen from Earth, this star is located about 177 light years from the Sun. It is moving away from the Sun with a radial velocity of +15.7 km/s.
This is an evolved K-type giant star with a stellar classification of K1 III. It has 1.59 times the mass of the Sun, while its diameter has been estimated as around 11 times that of the Sun. The star is radiating 61 times the Sun's luminosity from its enlarged photosphere at an effective temperature of around 4,600 K.


GQ Lupi

GQ Lupi is a T Tauri variable star approximately 495 light-years away in the constellation of Lupus. The star is young and has about 70% of the Sun's mass.
Possible planetary system.
In 2005, Ralph Neuhäuser and his colleagues reported a substellar object, GQ Lupi b, orbiting the star. Along with 2M1207b, this was one of the first extrasolar planet candidates to be directly imaged. The image was made with the VLT telescope at Paranal Observatory, Chile, on June 25, 2004. Depending on its mass and the definition of a planet, GQ Lupi b may or may not be considered a planet. As of 2006, the International Astronomical Union Working Group on Extrasolar Planets described GQ Lupi b as a "possible planetary-mass companion to a young star." "GQ Lupi b" is listed as "confirmed planet" as in 2020.
In 2020, another low-mass companion of GQ Lupi was discovered at a separation distance of about 16 arcsecods, or 2400 AU. Designated 2MASS J15491331-3539118 under the 2MASS catalogue, it is likely a young stellar object that is gravitationally bound to its primary star. It is estimated to be approximately 15% the Sun's mass and 21% the Sun's radius. It has an effective temperature of about 3190 K, indicating that it is a red dwarf with the spectral type M4.