Gamma Cephei Ab

Gamma Cephei Ab (abbreviated γ Cephei Ab, γ Cep Ab), formally named Tadmor , is an exoplanet approximately 45 light-years away in the constellation of Cepheus (the King). The planet was confirmed to be in orbit around Gamma Cephei A in 2002, but was first suspected to exist around 1988 (making this planet arguably the first "true" exoplanet discovered).
In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name for this planet was Tadmor. It was submitted by the Syrian Astronomical Association and is the ancient Semitic name and modern Arabic name for the city of Palmyra, a (UNESCO) World Heritage Site.
Detection and discovery.
1988 claims.
The first indications of Gamma Cephei Ab were reported in July 1988. The planet was tentatively identified by a Canadian team of astronomers, which was led by Bruce Campbell, Gordon Walker, and Stephenson Yang, while its existence was also announced by Anthony Lawton and P. Wright in 1989. Though not confirmed, this would have been the first "true" discovery of an extrasolar planet, and it was hypothesized based on the same radial velocity technique later used successfully by others. However, the claim was retracted in 1992 due to the quality of the data not being good enough to make a solid discovery.
2002 confirmation.
On September 24, 2002, Gamma Cephei Ab was finally confirmed. The team of astronomers (including William D. Cochran, Artie P. Hatzes, et al.) at the Planetary Systems and their Formation Workshop announced the preliminary confirmation of a long-suspected planet Gamma Cephei Ab with a minimum mass of 1.59 MJ (1.59 times that of Jupiter). The parameters were later recalculated when direct detection of the secondary star Gamma Cephei B allowed astronomers to better constrain the properties of the system. Gamma Cephei Ab moves in an elliptical orbit with a semimajor axis of 2.044 AU which takes almost two and a half years to complete. The eccentricity is 0.115, which means it moves between 1.81 and 2.28 AUs in orbital distance around Gamma Cephei A, which would place it from slightly beyond the orbit of Mars, to the inner asteroid belt in the solar system.
"Hipparcos" data taken in 2006 constrains its mass below "13.3 MJ at the 95% confidence level, and 16.9 MJ at the 99.73% (3 σ) confidence level". This is not much to go on, but it is enough to verify that it is not another unseen brown or red dwarf.


Beta Pictoris c

Beta Pictoris c (abbreviated as β Pic c) is the second exoplanet orbiting young star Beta Pictoris, located approximately 63 light-years away from Earth in the constellation of Pictor. Its mass is around nine times that of Jupiter, and it orbits at around 2.7 astronomical units (AU) from Beta Pictoris, about 3.5 times closer to its parent star than Beta Pictoris b. It has an orbital period of . The orbit of Beta Pictoris c is moderately eccentric, with an eccentricity of 0.24.
Physical characteristics.
Mass and radius.
Beta Pictoris c is a super-Jupiter, an exoplanet that has a radius and mass greater than that of the planet Jupiter. It has a mass of around 9 Jupiter masses () and a radius 1.12 times larger than Jupiter.
Host star.
The planet orbits an A-type main sequence star named Beta Pictoris. The star has a mass of 1.75 solar masses () and a radius of 1.8 solar radii (). It has a surface temperature of 8056 K and is only 12 million years old. It is slightly metal-rich, with a metallicity (Fe/H) of 0.06, or 112% of that found in the Sun. Its luminosity () is 8.7 times that of the Sun.
Orbit.
Beta Pictoris c orbits at around from Beta Pictoris, about 3.5 times closer than Beta Pictoris b. It has an orbital period of .
Discovery.
Beta Pictoris c was detected indirectly, through 10 years of observation of radial velocity data from the High Accuracy Radial Velocity Planet Searcher (HARPS) spectroscope on the European Southern Observatory's ESO 3.6 m Telescope at La Silla Observatory in Chile by a worldwide team led by Anne-Marie Lagrange, as the discovery of the planet was publicly announced in August 2019. This discovery was described as being able to help scientists further understand the formation of planetary systems and their evolution in the early stages. In October 2020, new images of the exoplanet were revealed.
Optical confirmation.
The European Southern Observatory confirmed the presence of Beta Pictoris c, on 6 October 2020, through the use of optical interferometry. With a semi-major axis of approximatively 2.7 astronomical units, Beta Pictoris c is, as of 2020, the closest extrasolar planet to its star ever photographed


HL Tau 76

HL Tau 76 is a variable white dwarf star of the DAV (or ZZ Ceti) type. It was observed by G. Haro and W. J. Luyten in 1961, and was the first variable white dwarf discovered when, in 1968, Arlo U. Landolt found that it varied in brightness with a period of approximately 749.5 seconds, or 12.5 minutes. Like other DAV white dwarfs, its variability arises from non-radial gravity wave pulsations within itself., § 7. Later observation and analysis has found HL Tau 76 to pulsate in over 40 independent vibrational modes, with periods between 380 seconds and 1390 seconds.


NGC 3357

NGC 3357 is an elliptical galaxy located in the constellation of Leo. It was discovered on April 5, 1864 by German astronomer Albert Marth.


Kepler-36b

Kepler-36b is an exoplanet orbiting the star Kepler-36. This planet has the closest conjunction to Kepler-36c every 97 days. Its density is similar to that of iron.
During their closest approach, Kepler-36b and Kepler-36c are located only 0.013 AU (about 1,900,000 km) from each other, which causes extreme transit-timing variations for both planets. Transit-timing variations caused by Kepler-36c are strong enough to put narrow constraints on Kepler-36b's mass. The close proximity of the planet to its host star combined with its relatively low mass caused the planet to lose all or most of its primordial hydrogen/helium envelope.


Berkeley 86

Berkeley 86 is a young open cluster in Cygnus. It is located inside the OB Stellar association Cyg OB 1, and obscured by a foreground dust cloud.


Epsilon Lupi

Epsilon Lupi, Latinized from ε Lup, is a multiple star system in the southern constellation of Lupus. At an apparent visual magnitude of 3.41, Epsilon Lupi can be readily viewed from the southern hemisphere with sufficiently dark skies. It is the fifth-brightest star or star system in the constellation. Parallax measurements give a distance to this system of roughly .
This system is what astronomers term a double-lined spectroscopic binary. When the spectrum is examined, the absorption line features of both stars can be viewed. As a result of the Doppler effect, these lines shift back and forth in frequency as the two stars orbit around each other. This allows some of their orbital elements to be deduced, even though the individual stars have not been resolved with a telescope. The pair share a close, elliptical orbit with a period of 4.55970 days. The orbital eccentricity is 0.277, which means that at the separation at closest approach, or periapsis, is only 57% of the distance at their greatest separation, or apoapsis. There is a third, more distant companion at an angular separation of around 1 arcsecond that may be orbiting the pair with a period of about 64 years.
The pair that share the close orbit, Epsilon Lupi Aa and Epsilon Lupi Ab, have estimated masses of 13.24 and 11.46 times the mass of the Sun, respectively. The more distant component, Epsilon Lupi B, has a mass of about 7.64 times the Sun. The combined stellar classification of the system is B2 IV-V, while the individual components may have spectral classes of B3 IV, B3 V, and A5 V, in order of decreasing mass. The inner A-a pair appear to have their rate of spin synchronized with their orbit, so that the same face of each star always faces its partner. The secondary, Epsilon Lupi a, shows regular variation in luminosity of the type that occurs with Beta Cephei variables, at a periodicity of 10.36 cycles per day.
This star system is a probable member of the Scorpius-Centaurus Association, a moving group of stars that originated together and share a similar trajectory through space.


C Carinae

The Bayer designations c Carinae and C Carinae are distinct.


WR 24

WR 24 (HD 93131) is a Wolf-Rayet star in the constellation Carina. It is one of the most luminous stars known. At the edge of naked eye visibility it is also one of the brightest Wolf Rayet stars in the sky.
The spectrum of WR 24 has the characteristic strong nitrogen and helium emission lines of a WN star, but also lines of hydrogen that show Doppler-displaced absorption components. The lowest ionisation nitrogen emission lines are strongest, with NV lines being very weak. The HeI lines are weaker than the HeII lines, leading to a WN6ha spectral class. The spectral type is annotated with a letter w, indicating weaker emission than for a typical WN6 star.
WR 24 is thought to be a member of the open cluster Collinder 228, sometimes considered to be just an extension of the rich cluster Trumpler 16. It lies on the southwestern side of the Carina Nebula. Collinder 228 and the Carina Nebula are approximately 2.2 kpc away. However, the Gaia Data Release 2 parallax gives a distance around for WR 24.
WR 24 has been reported to vary in brightness by about 0.02 magnitudes. Analysis of Hipparcos photometry shows an amplitude of 0.082 magnitudes and a primary period of 4.76 days. It has not yet been assigned a variable star designation in the General Catalogue of Variable Stars and is still formally listed as a suspected variable.
The hydrogen-rich WN stars have been referred to as WNL stars or as WNH stars since they do not necessarily have late nitrogen-sequence spectra. They are systematically more massive and more luminous than stars with similar spectra but lacking nitrogen. WR 24 has a mass of and is over two million times as luminous as the sun. These stars are proposed to be young hydrogen-burning stars, effectively main sequence objects, rather than post-supergiant stars. WR 24 is calculated to have 44% hydrogen in its atmosphere. The cluster Collinder 228 is thought to be around 6.78 million years old. The WR-type spectra are caused because helium and nitrogen and convected to the surface by the extreme temperature gradients caused by the CNO cycle in the core, and then expelled by powerful stellar winds. WR 24 has a wind reducing its mass by per year, at a velocity of 2,160 km/s.


Gliese 623

Gliese 623 is a dim double star 26.3 light years from Earth in the constellation Hercules. It was photographed by the NASA/ESA Hubble Space Telescope's Faint Object Camera in 1994. The binary system consists of two red dwarfs orbiting each other at a distance of 1.9 astronomical units.


Phi2 Cancri

Phi2 Cancri (φ2 Cancri) is a binary star in the constellation Cancer, about 280 light-years from Earth. Both components are white A-type main sequence dwarfs with apparent magnitudes of +6.3. They are separated by 5.126 arcseconds on the sky, and their mean apparent brightness is +5.55 magnitudes.


Tau Canis Majoris

Tau Canis Majoris (τ CMa, τ Canis Majoris, 30 CMa) is a multiple star system in the constellation Canis Major. It is approximately 5,000 light years distant from Earth and is the brightest member of the open cluster NGC 2362.
System.
τ Canis Majoris lies at the center of the very young open cluster NGC 2362 which contains several hundred stars. It is by far the brightest member of the cluster and the only one to have evolved away from the main sequence. A number of stars were catalogued by John Herschel as companions: component B is a 10th magnitude star 8.6 arc-seconds distant; component C is a 14th magnitude star 14.2 arc-seconds away; and component D is an 8th magnitude star at 85 arc-seconds. These stars are all thought to be main sequence members of NGC 2362. A period of 94,000 years has been suggested for the AB pair assuming they are gravitationally bound.
In 1951, component A was resolved into a double separated by only 0.15", with an estimated orbital period of 250 years. The Washington Double Star catalogue lists the pair as magnitude 4.89 Aa and magnitude 5.33 Ab, but the CCDM designates the components as A and P. A 10th magnitude component E was discovered in 2010. It is less than 1" away from the 4th magnitude main component.
The primary component A is itself a spectroscopic binary with a period of 154.918 days. The variable radial velocity was discovered in 1906 and the first orbit published in 1928. More recently, the Hipparcos satellite data revealed the existence of a 1.282 day eclipsing binary within the system, with two equal minima where the brightness dips by half a magnitude. The short period eclipsing pair is the fainter component of the two longer period spectroscopic binary, forming an unusual triple star with the most massive component orbiting pair of smaller stars. These three stars are referred to as Aa, Ab1, and Ab2, not to be confused with the fainter visible star 0.15 arc-seconds distant.
UW Canis Majoris is another 4th magnitude star less than half a degree away, and is itself an eclipsing binary system associated with NGC 2362. It has been catalogued as τ2 CMa, but that name is now rarely used.
Properties.
τ Canis Majoris appears as a class O supergiant at a distance of 5,000 light years within the open cluster NGC 2362, but this is composed of multiple stars. The properties of the minor components of the τ CMa system are poorly known. Component D has been described as having spectral type B2V, but this is uncertain. The relative brightnesses of the three spectroscopic components have been calculated from the eclipses and orbital movement. The spectrum, mass, and luminosity is dominated by component Aa which is now considered to be an O9 bright giant. It is thought to have a mass around , a temperature of 32,000 K, and a luminosity of . The two eclipsing stars are almost identical class B main sequence stars with masses around .
This star is sometimes known as the 'Mexican Jumping Star' by amateur astronomers, because it can appear to 'jump around' with respect to the other stars in the cluster because of its marked contrast in brightness.


R Sagittae

R Sagittae is an RV Tauri variable star in the constellation Sagitta that varies from magnitude 8.0 to 10.5 in 70.77 days. It is a post-AGB low mass yellow supergiant that varies between spectral types G0Ib and G8Ib as it pulsates. Its variable star designation of "R" indicates that it was the first star discovered to be variable in the constellation. It was discovered in 1859 by Joseph Baxendell, though classified as a semi regular variable until RV Tauri variables were identified as a distinct class in 1905.
R Sagittae is classified as an RV Tauri variable because of the distinctive regular variations with alternating deep and shallow minima. The period is conventionally quoted as the time between two deep minima and is the fundamental pulsation mode. The shallow minimum is the result of a first overtone pulsation. It is further classified as RVb since the average and maximum magnitude varies slowly over several years. The main period also varies over a period of decades. It has around 90% the mass of the Sun and an average effective (surface) temperature of around 5000 K. It is around 10,000 times as luminous as the Sun. Measurement of its parallax by the Gaia satellite yields a distance of around 8,100 light-years.
Variable star observer David Levy recommends that amateur observers monitor it once a week to observe changes in brightness.
RV Tauri variables are post-AGB stars, originally similar to the Sun but now in the last stages of their lives. They are crossing the Cepheid instability strip as they lose their outer layers on the way to becoming a planetary nebula. Although their spectra and luminosities resemble supergiants, they are old low mass population II stars. A period-colour-luminosity relationship has been derived from observations of RV Tauri variables in the Large Magellanic Cloud that is closely related to the relationship for type II Cepheid variables.


Geminga

Geminga is a neutron star approximately 250 parsecs (around 800 light-years) from the Sun in the constellation Gemini. Its name, attributed by its discoverer Giovanni Bignami, is both a contraction of Gemini gamma-ray source", and a transcription of the words ghè minga" (), meaning "it's not there" in the Milanese dialect of Lombard.
Pulsar.
The nature of Geminga was quite unknown for 20 years after its discovery by NASA's Second Small Astronomy Satellite (SAS-2). Finally, in March 1991 the ROSAT satellite detected a periodicity of 0.237 seconds in soft x-ray emission. Thus, it is supposed that Geminga is a sort of neutron star: the decaying core of a massive star that exploded as a supernova about 300,000 years ago.
It was once thought that this nearby explosion was responsible for the low density of the interstellar medium in the immediate vicinity of the Solar System. This low-density area is known as the Local Bubble. Possible evidence for this includes findings by the Arecibo Observatory that local micrometre-sized interstellar meteor particles appear to originate from its direction. More recently, however, it has been suggested that multiple supernovae in subgroup B1 of the Pleiades moving group were more likely responsible, becoming a remnant supershell.
A study from 2019, using data from NASA's Fermi Gamma-ray Space Telescope discovered a large gamma-ray halo around Geminga. Accelerated electrons and positrons collide with nearby starlight. The collision boosts the light up to much higher energies. Geminga alone could be responsible for as much as 20% of the high-energy positrons seen by the AMS-02 experiment. Previous studies using data from the High-Altitude Water Cherenkov Gamma-ray Observatory found only a small gamma-ray halo around Geminga at higher energies.
Discovery and identification.
Geminga was the first example of an unidentified gamma-ray source, a source which could not be associated with any objects known at other wavelengths. It was first detected as a significant excess of gamma rays over the expected background of diffuse Galactic emission, by the SAS-2 satellite (Fichtel "et al." 1975) and subsequently by the COS-B satellite. The SAS-2 group reported a pulsation in the gamma-ray signal, with period approximately 59 s, although the limited number of detected gamma rays (121 over a period of four months) led them to conclude that the pulsation was not statistically compelling. Due to the limited angular resolution of the instrument (approximately 2.5° at 100MeV) and the small number of gamma rays detected, the exact location of the source was uncertain, constrained only to be within a relatively large "error region". At the time of detection, four weak radio sources were known within this region, two supernova remnants bordered it and a known satellite galaxy to the Milky Way lay nearby. None of these known sources were convincing associations to the gamma-ray source, and the SAS-2 team suggested that an undiscovered radio-pulsar was the most likely progenitor.
Despite the investment of a significant amount of observation time, the source remained unidentified through the COS-B era; their data did, however, rule out the claimed 59 s pulsation. Many claims were made about the source during this time, but its nature remained a mystery until the identification of a candidate source by the Einstein x-ray satellite, 1E 0630+178. The characteristics of the x-ray source were unique: large x-ray to optical luminosity, no radio emission detected by the sensitive VLA instrument, point-like emission in the Einstein imager and an estimated distance of approximately 100 pc, placing it within the Galaxy. An association between the gamma-ray and x-ray sources was not conclusively made until the ROSAT x-ray imager detected a 237 ms pulsation, which was also seen in gamma rays by the EGRET instrument and retrospectively in the COS-B and SAS-2 data. Geminga thus appeared to be the first example of a radio-quiet pulsar, and served as an illustration of the difficulty of associating gamma-ray emission with objects known at other wavelengths: some characteristic of the gamma-ray source, such as periodicity or variability, must be identified in candidate counterparts at other wavelengths in order to make the connection of their identity.
Finally, this principle held true when radio emissions of matching 237 ms periodicity were found at previously unsurveyed frequencies of 100 MHz and below.
Proper motion.
The proper motion of Geminga is 178.2 mas/year which corresponds to a projected velocity of 205 kilometres per second. This is very fast for a star, comparable to Barnard's Star.
Timing measurements.
Geminga underwent a minor glitch in the late part of 1996, with a fractional change in frequency of 6.2 × 10−10. A 1998 study of the pre-glitch ephemeris suggested that the timings were being affected by reflex motion due to the presence of a low-mass planet in a 5.1-year orbit; however, this was later shown to be an artifact of noise that affects the pulse times from Geminga rather than a genuine orbital effect.


HD 73534

HD 73534 is an 8th magnitude G-type subgiant star located approximately 272 light years away in the constellation Cancer. A G5 star, it has evolved off the main sequence, which is why it is much more luminous than our Sun. In August 2009, it was announced that it has a planet. It is the first planetary system discovered in Cancer since that of 55 Cancri in April 1996, and the sixth planet, as 55 Cancri has five known planets.
The star HD 73534 is named Gakyid. The name was selected by Bhutan as part of the NameExoWorlds campaigns during the 100th anniversary of the IAU. Gakyid means happiness.


Mu Herculis

Mu Herculis (μ Herculis) is a nearby star system about 27.1 light years from Earth in the constellation Hercules. Its main star, Mu Herculis A is fairly similar to the Sun although more highly evolved with a stellar classification of G5 IV. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Its mass is about 1.1 times that of the Sun, and it is beginning to expand to become a giant.
Etymology.
In the catalogue of stars in the "Calendarium of Al Achsasi Al Mouakket", this star was designated "Marfak Al Jathih Al Aisr", which was translated into Latin as "Cubitum Sinistrum Ingeniculi", meaning "the left elbow of kneeling man".
In Chinese, (), the "Left Wall of Heavenly Market Enclosure", refers to an asterism which represents eleven old states in China, marking the left borderline of the enclosure, consisting of μ Herculis, δ Herculis, λ Herculis, ο Herculis, 112 Herculis, ζ Aquilae, θ1 Serpentis, η Serpentis, ν Ophiuchi, ξ Serpentis and η Ophiuchi. Consequently, the Chinese name for μ Herculis itself is (, ), represent "Jiuhe" (九河, lit. meaning "nine rivers"), possibly for Jiujiang, the prefecture-level city in Jiangxi, China, which is the same literally meaning with "Jiuhe". From this Chinese title, the name "Kew Ho" appeared.
Star system.
Mu Herculis is a quadruple star system. The brightest star is a well-studied G-type subgiant, whose parameters are precisely determined from asteroseismology. It was believed to be a close binary with a low-mass stellar or a large substellar companion. This was confirmed when low-mass companion was resolved using near-infrared spectroscopy. The companion star is a red dwarf with a spectral type of M4V and a mass of . This pair is also known as Mu1 Herculis.
The secondary component, also known as Mu2 Herculis, consists of a pair of stars that orbit about each other with a period of about 43 years. Mu Herculis A and the binary pair B-C are separated by some 35 arcseconds. The stars B and C, which orbit each other, are separated from each other by 1.385 arcseconds, and have a slightly eccentric orbit, at 0.1796.


Delta Caeli

Delta Caeli (δ Caeli) is a solitary, blue-white hued star in the southern constellation of Caelum. It is a dim star but visible to the naked eye, having an apparent visual magnitude of +5.06. Based upon an annual parallax shift of 4.63 mas as seen from Earth, this star is located roughly 700 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.13 due to interstellar dust.
This is a B-type star with a stellar classification of B2 IV-V, where the luminosity class IV-V indicates the spectrum shows mixed traits of a subgiant star and a main sequence star. It has 7−8 times the mass of the Sun and about 3.9 times the Sun's radius. The star is around nine million years old and is radiating 2,578 times the Sun's luminosity from its photosphere at an effective temperature of 21,150 K.


NGC 239

NGC 239 is a spiral galaxy located in the constellation Cetus. It was discovered in 1886 by Francis Leavenworth.


S Ursae Minoris

S Ursae Minoris (S UMi) is a long period variable star in the constellation Ursa Minor, ranging from magnitude 7.5 to fainter than 13.2 over a period of 331 days.


NGC 6886

NGC 6886 is a planetary nebula in the constellation Sagitta. It was discovered by Ralph Copeland on September 17, 1884. It is distant from earth, and is composed of a hot central post-AGB star that has 55% of the Sun's mass yet 2700 ± 850 its luminosity, with a surface temperature of 142,000 K. The planetary nebula is thought to have been expanding for between 1280 and 1600 years.


Magha (nakshatra)


Chi Puppis

χ Puppis, Latinised as Chi Puppis, is a single star in the southern constellation of Puppis. It has a white hue and is faintly visible to the eye at night with an apparent visual magnitude of 4.79. The star is located at a distance of approximately 1,800 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +30 km/s. O. J. Eggen listed this star as a member of the Hyades Stream based on its space motion.
There has been some disagreement as to the stellar classification of Chi Puppis. In 1962, W. Buscombe classified it as A2Vvar, matching a variable A-type main-sequence star. However, P. S. Conti in 1965 considered that to be a misclassification on the basis of its B-V color index. He considers it of later type A5. In their study of the nearby open cluster NGC 2483, M. P. Fitzgerald and A. F. J. Moffat used the same class, A2Vv. In 1979, Nancy Houk assigned it to class A7 III, indicating it may be an A-type giant star. Finally, R. O. Gray and associates found a class of A5 II, matching a bright giant.
In his star atlas "Neue Uranometrie", Friedrich Wilhelm Argelander labelled this star as χ Argo. It was probably labelled as χ by Bayer in the original "Uranometria", although Bayer's chart is somewhat fanciful. Nicolas-Louis de Lacaille changed Bayer's designations in Argo Navis and applied χ to the star now called χ Carinae.


C Puppis

The Bayer designations c Puppis and C Puppis are distinct and refer to two different stars in the constellation Puppus:


NGC 6570

NGC 6570 is a spiral galaxy in the constellation of Ophiuchus. It is part of the original New General Catalogue.


HD 93083

HD 93083 is an orange-hued star in the southern constellation of Antlia. It has the proper name Macondo, after the mythical village of the novel One Hundred Years of Solitude (Cien años de soledad). The name was selected by Colombia during the IAU's NameExoWorlds campaign. The star has an apparent visual magnitude of 8.30, which is too faint to be visible to the naked eye. It is located at a distance of 93 light years from the Sun based on parallax. HD 93083 is drifting further away with a radial velocity of +43.65 km/s, having come to within some 484,000 years ago.
This is a K-type main-sequence star that has been assigned a stellar classification of K2IV-V or K3V, depending on the study. It is smaller and less massive than the Sun, with a higher metallicity, or abundance of elements heavier than helium. The star is roughly six billion years old with a low projected rotational velocity of 2.2 km/s, and has an expected main sequence lifetime of 20.4 billion years. It is a source of X-ray emission with a luminosity of . The star is radiating around 41% of the luminosity of the Sun from its photosphere at an effective temperature of 5,030 K.
Planetary system.
In 2005, the discovery of an exoplanet orbiting the star was announced. This is another discovery using the radial velocity method with the HARPS spectrograph. The planet was given the name Melquíades by the IAU after a character in the book "One Hundred Years of Solitude". The orbit of this body lies entirely within the habitable zone of the host star, and it is theoretically possible that a large moon orbiting the body, or a hypothetical terrestrial exoplanet at a trojan point, is habitable.


NGC 7538

NGC 7538, near the more famous Bubble Nebula, is located in the constellation Cepheus. It is located about 9,100 light-years from Earth. It is home to the biggest yet discovered protostar which is about 300 times the size of the Solar System. It is located in the Perseus Arm of the Milky Way and is probably part of the Cassiopeia OB2 complex. It is a region of active star formation including several luminous near-IR and far-IR sources. Stars in NGC 7538 are mainly low-mass pre-main-sequence stars.


Kepler-33

Kepler-33 is a star in the constellation of Cygnus with a system of five known planets. Having just begun to evolve off from the main sequence, its radius and mass are difficult to ascertain, although data available in 2020 shows its best-fit mass of 1.3 and diameter of 1.6 are compatible with a model of a subgiant star.
Planetary system.
First detections of the four-body planetary system were reported in February 2011. On January 26, 2012, a 5th planet around the star was confirmed. However, unlike other planets confirmed via Kepler, their masses were initially not known, as Doppler Spectroscopy measurements were not done before the announcement. Judging by their radii, b may be a large Super-Earth or small Hot Neptune while the other four are all likely to be the latter.
Planets b and c may actually be in a 7:3 resonance, as there is a 0.05 day discrepancy; there is also a small 0.18 day discrepancy between a 5:3 resonance between planets c and d. The other planets do not seem to be in any resonances, though near resonances are 3d:2e and 4e:3f.
The planetary system in current configuration is highly susceptible to perturbations, therefore assuming stability, no additional giant planets can be located within 30 AU from the parent star.


List of stars in Sextans

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


25 Serpentis

25 Serpentis is a star system in the constellation of Serpens Caput. With an apparent magnitude of 5.37, it is just barely visible to the naked eye. The system is estimated to be some 450 light-years (138 parsecs) based on its parallax.
25 Serpentis is a spectroscopic binary, meaning that the individual components are too close to be resolved, but periodic Doppler shifts in their spectra indicate orbital motion. The system consists of a hot B-type giant and an A-type main-sequence star. The two stars orbit each other every 38.9 days, and have a very eccentric orbit, with an orbital eccentricity of 0.731. The primary is a slowly pulsating B-type star, which causes the system to vary by 0.03 magnitudes; for that reason it has been given the variable star designation PT Serpentis.


A2744 YD4

A2744_YD4 is a very distant young galaxy. This galaxy has first been identified as a possible distant galaxy in 2015 using Hubble. This detection was made possible because this galaxy lies behind the massive galaxy cluster Abell 2744. In 2017, ALMA observed it and detected a small quantity of dust (the most distant stardust to date) and the first signature of Oxygen emitting light only 600 million years after the Big Bang.


NGC 2859

NGC 2859 is a barred lenticular galaxy located some 83 million light years away in the constellation Leo Minor. The morphological classification is (R)SB(r)0+, where the S0+ notation indicates a well-defined physical structure that is lacking in visible spiral arms. It has a strong bar (B) of the "ansae" type, which means it grows brighter or wider toward the tips. A faint, secondary bar is positioned at nearly a right angle to the main bar. These features are surrounded by a weak inner ring (r) that appears diffuse. The outer region of the galaxy hosts a prominent, detached ring (R) that includes a series of blue-hued knots along the eastern side.
The central supermassive black hole is an estimated 105 million times the mass of the Sun. The nucleus is tentatively classified as a transition type T2:, with no indication of activity.


Delta Trianguli

Delta Trianguli (Delta Tri, δ Trianguli, δ Tri) is a spectroscopic binary star system approximately away in the constellation of Triangulum. The primary star is a yellow dwarf, while the secondary star is thought to be an orange dwarf. It has an apparent magnitude of +4.87 and forms an optical (line-of-sight) triple with Gamma Trianguli and 7 Trianguli.
Stellar components.
Delta Trianguli A is a main sequence star with a stellar classification of G0V and a mass similar to the Sun. The spectral characteristics of the smaller companion Delta Trianguli B are not well determined since the close orbit makes observations difficult, with estimates of the spectral class ranging from G9V to K4V. The Delta Trianguli stars orbit their center of mass with an estimated separation of 0.106 AU; it is certainly less than one AU. The orbital period is 10.02 days and the eccentricity of the orbit is only 0.020. The orbit is inclined about 167° to humans' line of sight.
A 2008 search for a tertiary companion to this system using an adaptive optics system on the VLT proved unsuccessful. Examination of the system in infrared light at 70 μm shows no excess emission that would otherwise indicate the presence of a disk of orbiting dust.
Naming.
In Chinese, (), meaning "Heaven's Great General", refers to an asterism consisting of δ Trianguli γ Andromedae, φ Persei, 51 Andromedae, 49 Andromedae, χ Andromedae, υ Andromedae, τ Andromedae, 56 Andromedae, β Trianguli and γ Trianguli. Consequently, the Chinese name for δ Trianguli itself is (, .).


HD 64760

HD 64760 (J Puppis) is a class B0.5 supergiant star in the constellation Puppis. Its apparent magnitude is 4.24 and it is approximately 1,660 light years away based on parallax.
The stellar wind structure of HD 64760 has been extensively studied. Its spectrum shows classic P Cygni profiles indicative of strong mass loss and high-velocity winds, but the spectral line profiles are also variable. The variation shows a 2.4 day modulation which is caused by non-radial pulsation of the star itself. Other pulsation periods around 4.81 hours have also been identified.
HD 64760 rotates rapidly. Despite its large size it completes a rotation every 4.1 days compared to every 27 days for the sun. This causes the star to be an oblate spheroid, with the equatorial radius 20% larger than the polar radius. It is estimated that the temperature of the photosphere is 23,300 K at the equator and 29,000 K at the poles, due to gravity darkening. In addition, the surface has temperature variations due to its pulsations. The effective temperature for the star as a whole is 24,600 K, to match the bolometric luminosity of .


Roof (Chinese constellation)

The Roof mansion () is one of the twenty-eight mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise.


37 Cancri

37 Cancri is a star in the zodiac constellation of Cancer. It is a challenge to view with the naked eye, having an apparent magnitude of 6.54. The star is moving away from the Earth with a heliocentric radial velocity of +22 km/s, having come as close as some 2.7 million years ago.
This is an ordinary A-type main-sequence star with a stellar classification of A1 V, which indicates it is generating energy through hydrogen fusion at its core. It is spinning with a projected rotational velocity of 35 km/s. The star has 2.7 times the mass of the Sun and around 1.8 times the Sun's radius. It is radiating 31 times the luminosity of the Sun from its photosphere at an effective temperature of 9,830 K.


NGC 2623

NGC 2623/Arp 243 is an interacting galaxy located in the constellation Cancer. NGC 2623 is the result of two spiral galaxies that have merged. Scientists believe that this situation is similar to what will occur to the Milky Way, which contains our solar system, and the neighboring galaxy, the Andromeda Galaxy in four billion years. Studying this galaxy and its properties have provided scientists with a better idea of the coming collision of the Milky Way and the Andromeda. Due to NGC 2623 being in the late stage of merging, the compression of the gas within the galaxy has led to a large amount of star formation, and to its unique structure of a bright core with two extending tidal tails.
Discovery.
NGC 2623 was discovered on January 19, 1885, by the French astronomer Édouard Jean-Marie Stephan. A significant discovery made within NGC 2623 was SN 1999gd. SN 1999gd is a Type 1a Supernova, and was discovered in 1999. This supernova is the result of the fusion of both the elements carbon and oxygen, which causes a gravitational collapse of the core of the white dwarf causing it to collapse.
Appearance.
The center of NGC 2623 is very bright and circular, and connected to it are two elongated tails, called tidal tails, of star clusters. Because of how bright it is, it is classified as a super luminous galaxy. The galaxy is very bright for both the radio waves and infrared waves it emits. There are two very distinct features of the X-rays that NGC 2623 emits. One is the spectral hard and compact, nuclear feature, and the other one is a cool feature that is not located in the nucleus. The cool feature of the X-rays is similar to X-ray outflows, that are observed around many other starburst galaxies, and this specific cool feature has a very diffuse structure is believed to be observed ejected gas, that comes from the inefficiency of star formation, as the process can't turn all matter into stars, therefore ejecting excess gas by supernova explosions, and stellar and galactic winds.
Merging.
NGC 2623 is in the late stage of merging, and is called a titanic galaxy merger. The centers of the galaxies that have formed NGC 2623 have already collided, forming the bright and circular center of NGC 2623, which is very prominent. One true nucleus is believed to exist in this galaxy, and it is symmetric. There have been inferences made that state that the merger should create a region of both compressed gas and dust, due to the observations that gas clouds are colliding within NGC 2623.
Properties.
Physical properties.
NGC 2623 spans 50 thousand light years.
The infrared luminosity of this galaxy is 3.3×1011 L☉ (solar luminosity). This level of emission is seen in Seyfert Galaxies, whose cores are especially bright.
The distance modulus is 34.50.
Classification.
The nucleus of this galaxy is filled with many young stars, due to the star formation caused by the merger. Because there is a such a large amount, NGC 2623 is classified as a Seyfert Galaxy. Seyfert Galaxies have very bright cores and similar properties to quasars. Both are nuclei of galaxies that contain active super massive black holes and emit very high levels of energy. Seyfert Galaxies, such as NGC 2623, tend to emit a much lower amount of visible light. Seyfert galaxies are relatively uncommon as only 2 percent of spiral galaxies fall under this classification.
Star formation.
In NGC 2623 there are bright star clusters in the tails of the galaxy, and many of them are situated in the upper tail. There are at least 170 star clusters within the galaxy. In addition to this both tails contain many young stars in their respective early stages in evolution. The most active part of the galaxy in regards to star formation is the upper and more prominent tail. Through HST and GALEX, which are two space telescopes, images it is evident that recent star formation has occurred within the galaxy. Though there are many star clusters in the tails of NGC 2623, the nucleus, or center of the galaxy still is responsible for more than 99 percent of the star formation occurring.
Tidal tails.
The large trails of gas on each end of NGC 2623 are known as tidal tails. Tidal tails are long strips of bright star clusters that occur due to the interactions between different galaxies. In the case of this galaxy, the tidal tails are formed due to the merging of the galaxies that formed NGC 2623. Tidal tails are very strong indicators of whether a galaxy has been formed due to the merging of multiple other galaxies. Tidal tails can also be seen in the Antennae galaxy, as they were also formed by the merging of galaxies, similar to how NGC 2623 was formed. Tidal tails are helpful to astronomers as they can indicate the formation and evolution of a galaxy.
Environment.
NGC 2623 is located in the direction of the constellation Cancer at a distance of 253 million light years from the Earth. It travels away from the Earth at a speed of approximately 5,500 kilometers per second.


Koposov 2

Koposov 2 is a low-luminosity globular cluster in the constellation Gemini in the halo of the Milky Way galaxy. It was discovered, along with globular cluster Koposov 1 by S. Koposov et al. in 2007. Koposov 1 and Koposov 2 were described by their discoverers as the "lowest luminosity globular clusters orbiting the Milky Way," along with AM 4, Palomar 1, and Whiting 1.


Gamma Sextantis

Gamma Sextantis, Latinized as γ Sextantis, is a binary star system in the equatorial constellation of Sextans. The combined apparent visual magnitude of the system is 5.05, which means it is faintly visible to the naked eye. The annual parallax shift is 11.75 mas, indicating a distance of around 280 light years.
The two components orbit each other with a period of 77.55 years and a high eccentricity of 0.691. The orbital plane is inclined by 145.1° to the line of sight from the Earth. With a visual magnitude of 5.6, the brighter component A is an A-type main sequence star with a stellar classification of A1 V. The fainter companion B has a classification of A4 V with a magnitude of 6.0. Their combined spectral matches a classification of A0/1 V.
There is a magnitude 12.28 companion star C at an angular separation of 36.9 arc seconds along a position angle of 333°, as of 2000. This separation has increased from 30.0 arc seconds in 1834. The proper motion of this star differs from the Gamma Sextantis AB system, having components "μα" = −29 mas/yr and "μδ" = +5 mas/yr.


Supreme Palace enclosure

Tai Wei Yuan, the Supreme Palace Enclosure (太微垣), is one of the San Yuan or Three enclosures. Stars and constellations of this group are visible during spring in the Northern Hemisphere (autumn in the Southern).
Asterisms.
The asterisms are :


NGC 6028

NGC 6028 is a barred lenticular galaxy and a ring galaxy located about 200 million light-years away in the constellation Hercules. Ring galaxies such as NGC 6028 are also known Hoag-type galaxies as they may have a resemblance to the prototype, Hoag's Object. NGC 6028 was discovered by astronomer William Herschel on March 14, 1784. It was then rediscovered by astronomer Guillaume Bigourdan on May 4, 1886.
Physical Characteristics.
NGC 6028 consists of a luminous core that is surrounded by a fainter outer ring. Unlike Hoag's Object, NGC 6028's core is elongated indicating the presence of a weak bar embedded in a lens-like structure. The outer ring of the galaxy appears asymmetric in structure and may be made up of tightly wound spiral arms. The observed asymmetry could be the result of one arm being richer in H II regions than the other arm.
Group Membership.
NGC 6028 appears to lie near the Hercules cluster in the sky. However, NGC 6028 is not a member of that cluster but instead belongs to a foreground group of galaxies known as G47.


HD 92063

HD 92063 is a single star in the southern constellation of Carina. It has the Bayer designation t1 Carinae, while "HD 92063" is the star's identifier from the "Henry Draper Catalogue". This is a suspected variable star and is visible to the naked eye with an apparent visual magnitude of 5.08. The star is located at a distance of approximately 246 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −10 km/s. Although it appears at the edge of the Carina Nebula, it is much closer than the nebula. It is also not considered a member of the nearby Alessi 5 open cluster of stars.
This is an aging K-type giant star with a stellar classification of K1III, having exhausted the supply of hydrogen at its core then cooled and expanded off the main sequence. At present it has 14 times the radius of the Sun. The star is radiating 72 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,520 K.


NGC 6375

NGC 6375 is a galaxy in the New General Catalog. It is located in the sky within the constellation Hercules. It is an E0 type lenticular, elliptical galaxy. It was discovered by German astronomer Albert Marth in 1864 with a mirror type telescope with a diameter of 121.92 cm (48 inches).


66 Aurigae

66 Aurigae is a single star located approximately 880 light years away from the Sun in the northern constellation of Auriga. It is visible to the naked eye as a faint, orange hued star with an apparent magnitude of 5.23. This object is moving further from the Earth with a heliocentric radial velocity of +22.6 km/s.
At the age of 107 million years, 66 Aurigae is an evolved giant star, most likely (98% chance) on the horizontal branch, with a stellar classification of K0.5 IIIa. Keenan and Yorka (1987) identified it as a strong–CN star, showing an excess strength of the blue CN bands in the spectrum. Having exhausted the supply of hydrogen at its core, the star has expanded to 48 times the Sun's radius. 66 Aurigae has five times the mass of the Sun and is radiating 834 times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,475 K.


NGC 3455

NGC 3455 is an intermediate spiral galaxy located 65 million light-years away in the constellation of Leo.


NGC 3506

NGC 3506 is a spiral galaxy in constellation Leo. It is located at a distance of circa 300 million light years from Earth, which, given its apparent dimensions, means that NGC 3506 is about 115,000 light years across. The galaxy has two main spiral arms, with high surface brightness, which can be traced for half a revolution before they fade. One arm splits into four spiral arcs.
Two supernovae have been observed in NGC 3506, SN 2003L (type Ic) and 2017dfq (type Ia, mag. 15.3). SN 2003L spectrum featured a relatively blue continuum, dominated by strong P-Cyg lines of Ca II (H and K) and Fe II and a relatively weaker Si II 635.5-nm line was also visible.
It is an isolated galaxy.


HD 73389

HD 73389 is a binary star system in the constellation Carina. It has the Bayer designation e2 Carinae; "HD 73389" is the identifier from the "Henry Draper Catalogue". This system is visible to the naked eye as a point of light with a combined apparent visual magnitude of +4.84. Based on parallax measurements, it is located at a distance of approximately 225 light years from the Sun. The system is drifting further away with a radial velocity of +25.6 km/s.
The visual magnitude 5.08 primary, component A, is an aging K-type giant star with a stellar classification of K0III. With the supply of hydrogen at its core exhausted, it has cooled and expanded to 11 times the Sun's radius. It is radiating 64 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,903 K. The secondary companion, component B, has a visual magnitude of 8.02 and is located at an angular separation of along a position angle of 207° from the primary, as of 2015.


Tau8 Serpentis

Tau8 Serpentis, Latinized from τ8 Serpentis, is an A-type main sequence star in the constellation of Serpens, approximately 320 light-years from the Earth. It has an apparent visual magnitude of approximately 6.144. Although it was observed to be binary by speckle interferometry in 1985, subsequent observations show no sign of binarity, and the detection appears to have been spurious.


NGC 263

NGC 263 is a spiral galaxy located in the constellation Cetus. It was discovered in 1886 by Francis Leavenworth.


NGC 6544

NGC 6544 is a small globular cluster visible in the constellation Sagittarius. It is magnitude 7.5, diameter 1 arc minute. It is less than 1 degree southeast of Messier 8, the lagoon nebula.
Observation.
NGC 6544 is located in the western part of the constellation, on the edge of a rich star field; its location is easily recoverable as it is located just 50' towards the southeast compared to the famous Lagoon Nebula. It can also be noted with a binoculars 10×50mm as a small white spot like a misty star; with a telescope 120mm and 100× magnification around you may notice a few tiny little star, but overall the clutter is almost unsolvable. Telescopes from 200mm up and high magnification allow resolving of dozens of dim stars.
Because of its declination is rather south, this cluster can be mainly observed by observers located in southern hemisphere, although it is still observable fairly even up to medium temperate latitudes. The best time for observation in the evening sky is the one included between June and October.
History of observations.
NGC 6544 was observed for the first time by William Herschel in 1784, who watched through his 18.4 inch reflector; he described it as a fairly bright and large object, circular and resolvable into stars; in New General Catalogue provides a similar description.
Characteristics.
NGC 6544 is a globular cluster of medium density, estimated value of 5 on a scale between 1 and 12. Its distance is estimated at 2900 parsecs (9450 light years) from the Sun, which in its position corresponds to a distance of 6100 parsecs from the center of the Milky Way and only 100 parsecs from the galactic plane, making it one of the closest globular clusters to known galactic plane known. Its small angular size, equal to just under 4' for the main body volume and corresponding to just 3.2 parsecs, makes it also one of the smaller globular clusters known.
In 1999 she was discovered within the cluster a pulsar in a binary system of type millisecond, cataloged as PSR J1807-2459; There are few notes variable stars part of this cluster; a 1993 study focused on the region around NGC 6544 has identified some variable stars, of which only one is found to belong in storage: it is a RR Lyrae variable with a period of 0.57 days.


NGC 494

NGC 494, also occasionally referred to as PGC 5035 or GC 282, is a barred spiral galaxy in the constellation Pisces. It is located approximately 227 million light-years from Earth and was discovered on 22 November 1827 by astronomer John Herschel. John Dreyer, creator of the New General Catalogue, described the galaxy as "very faint, pretty large, extended, 3 faint stars to south".


V343 Carinae

V343 Carinae is a blue-white star or star system in the southern constellation of Carina. It has the Bayer designation "d Carinae", while "V343 Carinae" is a variable star designation. The star is visible to the naked eye with an apparent visual magnitude of 4.31. The distance to this object is approximately 1,440 light years based on parallax. It is drifting further away with a radial velocity of +13 km/s.
This star was originally thought to be a Beta Cephei variable and a suspected eclipsing binary with an orbital period of 133.92 days. It is now considered as probably constant. Measurements indicate that at most it is a microvariable star with an amplitude of 0.0041 in visual magnitude and a period of 0.42029 cycles per day. Eggleton and Tokovinin (2008) catalogued this as a single star, albeit with some uncertainty. However, Chini et al. (2012) listed it as a single-lined spectroscopic binary system.
The visible component of V343 Carinae has a stellar classification of B1.5III, matching a massive blue giant. It has 12.5 times the mass of the Sun and is an estimated 16 million years old. The star is radiating 6,323 times the Sun's luminosity from its photosphere at an effective temperature of 27,600 K. It has a visual magnitude 13.3 companion at an angular separation of along a position angle of 339°, as of 2010.


NGC 7069

NGC 7069 is a Lenticular galaxy located about 400 million light-years away in the constellation of Aquarius. NGC 7069 is also classified as a LINER galaxy. NGC 7069 was discovered by astronomer Albert Marth on October 12, 1863.


Delta Cassiopeiae

Delta Cassiopeiae (δ Cassiopeiae, abbreviated Delta Cas, δ Cas) is an eclipsing binary star system in the northern circumpolar constellation of Cassiopeia. Based on parallax measurements taken during the Hipparcos mission, it is approximately from the Earth.
Delta Cassiopeiae is the primary or 'A' component of a multiple star system designated WDS J01258+6014. Delta Cassiopeiae's two components are therefore designated WDS J01258+6014 Aa and Ab. Aa is officially named Ruchbah , the traditional name for the system.
Nomenclature.
"δ Cassiopeiae" (Latinised to "Delta Cassiopeiae") is the star's Bayer designation. WDS J01258+6014A is its designation in the Washington Double Star Catalog.
It also bore the traditional names "Ruchbah" and "Ksora"; the former deriving from the Arabic word ركبة "rukbah" meaning "knee", and the latter appeared in a 1951 publication, "Atlas Coeli" (Skalnate Pleso Atlas of the Heavens) by Czech astronomer Antonín Bečvář. Professor Paul Kunitzch has been unable to find any clues as to the origin of the name. The star Alpha Sagittarii also bore the traditional name "Ruchbah" (as well as "Rukbat"). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name "Ruchbah" for the component WDS J01258+6014 Aa on 21 August 2016 and it is now so included in the List of IAU-approved Star Names (Alpha Sagittarii's primary was given the name "Rukbat").
In Chinese, (), meaning "Flying Corridor", refers to an asterism consisting of Delta Cassiopeiae, Iota Cassiopeiae, Epsilon Cassiopeiae, Theta Cassiopeiae, Nu Cassiopeiae and Omicron Cassiopeiae. Consequently, the Chinese name for Delta Cassiopeiae itself is (, ).
Properties.
Delta Cassiopeiae is a possible eclipsing binary star system consisting of a pair of stars that orbit about each other over a period of 759 days. The combined apparent visual magnitude of the two stars is 2.68, making it readily observable with the naked eye. Eclipses have been reported with a period of 759 days, when the brightness drops by 0.07 magnitudes. Modern studies have shown no brightness variations greater than 0.01 magnitudes.
The primary member of the system (WDS J01258+6014 Aa) has a stellar classification of A5 IV, with the luminosity class of IV indicating that it has exhausted the hydrogen at its core and has begun to evolve through the subgiant phase into a giant star. It is calculated that it is 4% beyond the end of its main sequence lifetime, with an age of about 600 million years. It has expanded to about 3.9 times the Sun's radius.
An excess infrared emission has been observed at a wavelength of 60 μm, which suggests the presence of a circumstellar debris disk. This emission can be characterized by heat radiated from dust at a temperature of 85 K, which corresponds to an orbital radius of 88 Astronomical Units, or 88 times the distance of the Earth from the Sun. For comparison, the region of the remote Kuiper belt in the Solar System extends from 30–50 AU.
The Washington Double Star Catalog lists a 12th magnitude companion away. It is an unrelated background object.


29 Herculis

29 Herculis is a single star located around 351 light years away from the Sun in the northern constellation of Hercules, a few degrees away from Omega Herculis. It has the Bayer designation h Herculis, while "29 Herculis" is the Flamsteed designation. This star is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.84. It is moving further from the Earth with a heliocentric radial velocity of +3 km/s. The star has a relatively high proper motion, traversing the celestial sphere at the rate of 0.195 arc seconds per annum.
This is an aging giant star with a stellar classification of K4.5 III. It displays an enhanced abundance of elements generated through the alpha process, and, in particular, has a strong enhancement of silicon. 29 Herculis is a suspected variable star of unknown type, and has been measured ranging in visual magnitude from 4.82 down to 4.85. It is an estimated 6.53 billion years old with 1.19 times the mass of the Sun. Having exhausted the supply of hydrogen at its core, it has expanded to 42 times the Sun's radius. The star is radiating 384 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,958 K.


List of Nakshatras

In Hindu puppitar, there are 27 nakshatras ("lunar mansions", Sanskrit: नक्षत्र, IAST: "Nakṣatra"), or sectors along the ecliptic. A list of them is first found in the "Vedanga Jyotisha", a text dated to the final centuries BCE. The "Nakṣatra" system predates the influence of Hellenistic astronomy on Vedic tradition, which became prevalent from about the 2nd century CE. There are various systems of enumerating the "Nakṣatra"-s; although there are 27-28 days to a sidereal month, by custom only 27 days are used. The following list gives the corresponding regions of sky.
Padas (quarters).
The 27 Nakshatras cover 13°20’ of the ecliptic each. Each Nakshatra is also divided into quarters or "padas" of 3°20’, and the below table lists the appropriate starting sound to name the child. The 27 nakshatras, each with 4 padas, give 108, which is the number of beads in a japa mala, indicating all the elements (ansh) of Vishnu:
Names in Indian and Asian languages.
The names of nakshatras in other languages are adapted from the Sanskrit variation (apabhramsa) through Pali or Prakrit. The variations evolved for easier pronunciation in popular usage.


Pi Capricorni

Pi Capricorni, Latinized from π Capricorni, is a triple star system in the southern constellation of Capricornus. It has the traditional star name Okul or Oculus (meaning "eye" in Latin). This system appears blue-white in hue and is visible to the naked eye as a 5th magnitude star. It is located approximately 660 light years distant from the Sun based on parallax, but is drifting closer with a radial velocity of −13 km/s.
In Chinese, (), meaning "Ox (asterism)", refers to an asterism consisting of π Capricorni, β Capricorni, α2 Capricorni, ξ2 Capricorni, ο Capricorni and ρ Capricorni. Consequently, the Chinese name for π Capricorni itself is (, .)
The primary member, component A, is a spectroscopic binary whose two components are separated by 0.1 arcseconds. The brighter of the two, component Aa, is a blue-white B-type bright giant or main sequence star with an apparent magnitude of +5.08. It is around 43 million years old with six times the mass of the Sun. The star is radiating 238 times the Sun's luminosity from its photosphere at an effective temperature of 9,623 K. The third member, component B, is an eighth magnitude star at an angular separation of from the primary.


ET Andromedae

ET Andromedae is a binary star system star in the northern constellation of Andromeda. It has an apparent visual magnitude of 6.48, placing it at the nominal limit for visibility with the naked eye. The distance to this system can be estimated from its annual parallax shift of , which yields a value of 602 light years.
Variations in the radial velocity of this star suggest it is a single-lined spectroscopic binary system. This yields orbital elements with a period of 48.3 days and an eccentricity of 0.50. The "a" sin "i" value for the primary is , where "a" is the semimajor axis and "i" is the (unknown) orbital inclination.
The visible component is a well-studied magnetic chemically peculiar star with a stellar classification of . The SiSr notation indicates unusual abundances of silicon and strontium in the spectrum. It has a magnetic field with an average surface value of . The abundance of silicon varies depending on the viewing angle. The star is an Alpha2 Canum Venaticorum variable with a period of 1.618875 days.


List of stars in Horologium

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


HD 44594

HD 44594 is a star in the southern constellation Puppis. It has an apparent visual magnitude of 6.64, so it can be seen with the naked eye from the southern hemisphere under good viewing conditions. Based upon parallax measurements, it is located at a distance of about from the Earth, giving it an absolute magnitude of 4.56.
Measurement of the star's spectrum show it to match a stellar classification of G1.5V, which is close to the Sun's spectral class of G2V. In the wavelength range 3200–8800 Â, the energy emission of this star is very similar to the Sun, and thus it is considered a solar analog. The luminosity class 'V' means this is a main sequence star that is generating energy through the thermonuclear fusion of hydrogen at its core. The effective temperature of the outer envelope of HD 44594 is 5,840 K, which is giving it the characteristic yellow hue of a G-type star.
This star has about 108% of the Sun's mass and is about the same radius as the Sun. It may be slightly younger than the Sun with an estimated age of 4.1 billion years. the abundance of elements other than hydrogen or helium, what astronomers term the star's metallicity, is 41% higher than in the Sun. The projected rotational velocity of the star is 4.4 km s−1, which gives the minimum azimuthal velocity along the star's equator.
This star has been examined in the infrared using the Spitzer Space Telescope. However, no excess emission was discovered, which might otherwise have indicated the presence of a circumstellar debris disk of orbiting dust.


HD 54893

HD 54893 is a class B2IV (blue subgiant) star in the constellation Puppis. Its apparent magnitude is 4.83 and it is approximately 730 light years away based on parallax.
It is a Beta Cephei variable.


A Hydrae

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


HR 3833

HR 3833 is a K-type giant star in the constellation of Antlia. It shines with a vis mag of 5.63 from a distance of 280 ly. HR 3833 is also known by its designations HD 83380 and HIP 47199.


Epsilon Canis Majoris

Epsilon Canis Majoris (Latinised from ε Canis Majoris, abbreviated Epsilon CMa, ε CMa) is a binary star and, despite being designated ε (epsilon), it is the second-brightest object in the constellation of Canis Major and the 22nd-brightest star in the night sky with an apparent magnitude of 1.50. About 4.7 million years ago, it was the brightest star in the sky, with an apparent magnitude of −3.99. Based upon parallax measurements obtained during the Hipparcos mission, it is about 430 light-years distant from the Sun.
The two components are themselves designated ε Canis Majoris A (also officially named Adhara , the traditional name of the system) and B.
Nomenclature.
"ε Canis Majoris" (Latinised to "Epsilon Canis Majoris") is the binary system's Bayer designation. The designations of the two components as "ε Canis Majoris A" and "B" derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
ε Canis Majoris bore the traditional name "Adhara" (sometimes spelled "Adara", "Adard", "Udara" or "Udra"), derived from the Arabic word عذارى 'aðāra', "virgins". 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 star systems. It approved the name "Adhara" for the star ε Canis Majoris A on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
In the 17th-century catalogue of stars in the "Calendarium" of Al Achsasi al Mouakket, this star was designated "Aoul al Adzari" (أول العذاري "awwal al-adhara"), which was translated into Latin as "Prima Virginum", meaning "First of the Virgins". Along with δ Canis Majoris (Wezen), η Canis Majoris (Aludra) and ο2 Canis Majoris (Thanih al Adzari), these stars were "Al ʽAdhārā" ("العذاري"), 'the Virgins'.
In Chinese, (), meaning "Bow and Arrow", refers to an asterism consisting of ε Canis Majoris, δ Canis Majoris, η Canis Majoris, κ Canis Majoris, ο Puppis, π Puppis, χ Puppis, c Puppis and k Puppis. Consequently, ε Canis Majoris itself is known as (, ).
Namesake.
USS "Adhara" (AK-71) was a U.S. Navy "Crater"-class cargo ship named after the star.
Physical properties.
ε Canis Majoris is a binary star. The primary, ε Canis Majoris A, has an apparent magnitude of +1.5 and belongs to the spectral classification B2. Its color is blue or blueish-white, due to the surface temperature of 22,200K. It emits a total radiation equal to 38,700 times that of the Sun. This star is the brightest source of extreme ultraviolet in the night sky.
It is the strongest source of photons capable of ionizing hydrogen atoms in interstellar gas near the Sun, and is very important in determining the ionization state of the Local Interstellar Cloud.
The +7.5-magnitude (the absolute magnitude amounts to +1.9) companion star, ε Canis Majoris B, is 7.5" away with a position angle of 161° of the main star. Despite the relatively large angular distance the components can only be resolved in large telescopes, since the primary is approximately 250 times brighter than its companion.
A few million years ago, ε Canis Majoris was much closer to the Sun than it is at present, causing it to be a much brighter star in the night sky. About 4.7 million years ago, Adhara was 34 light-years from the Sun, and was the brightest star in the sky with a magnitude of –3.99. No other star has attained this brightness since, nor will any other star attain this brightness for at least five million years.
In culture.
ε Canis Majoris appears on the national flag of Brazil, symbolising the state of Tocantins.


39 Eridani

39 Eridani is a wide binary star system in the equatorial constellation of Eridanus. It is visible to the naked eye as a faint, orange-hued star with a combined apparent visual magnitude of 4.87. As of 2015, the components had an angular separation of along a position angle of 143°. The system is moving further from the Sun with a heliocentric radial velocity of +7 km/s.
The magnitude 5.07 primary, designated component A, is an aging giant star with a stellar classification of K3 III. This object is more than a billion years old with 1.77 times the mass of the Sun. With the hydrogen at its core exhausted, the star has expanded to 12 times the Sun's radius. It is a candidate super metal-rich star, showing a significant overabundance of iron compared to the Sun. 39 Eridani A is radiating 81.3 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,641 K.
The secondary, component B, is a magnitude 8.68 G-type main-sequence star with a class of G2 V. It has 1.15 times the Sun's radius and shines with 1.37 times the luminosity of the Sun at an effective temperature of 5,816 K.


HD 35984

HD 35984 is star in the northern constellation Auriga. It has an apparent magnitude of 6.20, which, according to the Bortle scale, indicates it is faintly visible to the naked eye from dark rural skies. Parallax measurements by the Hipparcos satellite indicates it lies at a distance of roughly 290 light years away.
A stellar classification of F6III suggests that this is an evolved giant star that has consumed the supply of hydrogen at its core. However, X-ray emission, variations in luminosity, and levels of lithium may indicate that this is instead a weak-lined T Tauri star—a low mass pre-main sequence star that is relatively poor in circumstellar matter.


S Orionis

S Orionis is an asymptotic giant branch star in the constellation Orion, approximately away. It varies regularly in brightness between extremes of magnitude 7.2 and 14 every 14 months.
Variability.
S Orionis is a Mira variable that pulsates with an approximately 420‑day cycle, and varies in radius from 2.0 to 2.3 astronomical units. The pulsations have been observed using VLTI and VLBA observations which measured an angular diameter varying between 7.9 and 9.7 mas.
The mean period of variation has been shown to change over time, from less than 410 days to over 440 days. The variations are approximately sinusoidal with a weak, not statistically-significant, trend towards longer period. The cycle of period changes is around 70 years within a total observation period of only about 100 years, so it is difficult to be certain about long-term behaviour. However, this behaviour is not expected to be the result of thermal pulses or evolutionary changes, and the cause is unknown.
Companion.
S Orionis is listed in the Washington Double Star Catalog as a double star with a tenth magnitude companion 47" away. The companion is G0 star HD 294176.
Circumstellar environment.
S Orionis is surrounded by masers and dust condensed from its cool stellar wind. The size of the dust shells varies as the star pulsates and changes temperature, from around 8 AU to 10 AU across. The positions of the masers have been measured very accurately using VLBI.


36 Arietis

36 Arietis is a star in the northern constellation of Aries. "36 Arietis" is the Flamsteed designation. It is a dim, orange-hued star that is a challenge to view with the naked eye, having an apparent visual magnitude of 6.40. Based upon an annual parallax shift of , this star is located away from the Sun. It is moving closer to the Earth with a heliocentric radial velocity of −34 km/s, and is a member of the Wolf 630 moving group of stars that share a common motion through space.
This object is an evolved giant star with a stellar classification of K2 III. It is around two million years old with a similar mass as the Sun. With the hydrogen at its core exhausted, the star has expanded to ten times the girth of the Sun. It has a higher than solar metallicity, showing a high abundance of iron in its spectrum. The star is radiating 44 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,749 K.


HD 85390

HD 85390 is a main sequence star of spectral class K1 located approximately 109 light years away in the constellation Vela, appearing as 8.55 magnitude star. This star is smaller, cooler, dimmer, and less massive than our Sun. Also its metal content is seven-sixths as much as the Sun. In 2009, a planet with a minimum mass of about 1/7 of Jupiter's was found in orbit around the star.
The star HD 85390 is named Natasha. The name was selected in the NameExoWorlds campaign by Zambia, during the 100th anniversary of the IAU. Natasha means thank you in many languages of Zambia.
Planetary system.
The planet b as detected by radial velocity method in 2011. An additional planet in the system was suspected since 2013, only to be refuted in 2019.
The name Natasha on the moon.
A crater near Mons Vinogradov at the southwestern section of Mare Imbrium received the name Natasha shortly after the conclusion of the Apollo program. This crater was previously known as Euler P.


T Coronae Australis

T Coronae Australis (T CrA), is a young star in the constellation Corona Australis. It is a member of the Corona Australis star-forming region, which is located about from the Sun. It has a spectral type of F0e and is surrounded by a circumstellar disk, seen edge-on.


Delta Centauri

Delta Centauri, Latinized from δ Centauri, is a star in the southern constellation of Centaurus. The apparent visual magnitude of this star is +2.57, making it readily visible to the naked eye. Based upon parallax measurements, it is located at a distance of about from the Earth.
Properties.
δ Centauri is a shell star, with a distinctive spectrum created by material thrown off into a disk by its rapid rotation. It is also a variable star whose brightness varies from magnitude +2.51 to +2.65. It has been classified as a γ Cassiopeiae type variable. The energy from this star is being radiated at an effective temperature of over 22,000 K from the outer envelope, giving it the blue-white hue of a B-type star. It has a radius of 6.5 times the radius of the Sun and 8.7 times the Sun's mass.
The stellar classification of this star is B2 IVne, with the luminosity class of IV indicating that this is a subgiant star that has exhausted the hydrogen at its core and begun to evolve away from the main sequence. The star is spinning rapidly, with the resulting Doppler effect giving its spectrum broad absorption lines as indicated by the 'n'. The suffix 'e' means this is a classical Be star, which is a type of hot star that has not yet evolved into a supergiant and is surrounded by circumstellar gas. The presence of this gas creates an excess emission of infrared, along with emission lines in the star's spectrum. Most of it is concentrated around the equator, forming a disk.
Some of the variation in this star may be explained by assuming it is a binary star system. This proposed secondary star would need to have about 4–7 times the Sun's mass and be orbiting with a period of at least 4.6 years at a minimum separation of 6.9 Astronomical Units. δ Centauri shares a common proper motion with the nearby stars HD 105382 and HD 105383, so they may form a small cluster or perhaps a triple star system. It is a proper motion member of the Lower-Centaurus Crux sub-group in the Scorpius-Centaurus OB association, the nearest such of association of co-moving massive stars to the Sun.
Etymology.
In Chinese, (), meaning "Horse's Tail", refers to an asterism consisting of δ Centauri, G Centauri and ρ Centauri. Consequently, δ Centauri itself is known as (, .). From this Chinese name, the name Ma Wei appeared.
The people of Aranda and Luritja tribe around Hermannsburg, Central Australia, named Iritjinga, "The Eagle-hawk", a quadrangular arrangement comprising this star, γ Cen (Muhlifain), γ Cru (Gacrux), and δ Cru (Imai).


R Microscopii

R Microscopii is a star in the constellation Microscopium. It is a red giant star of spectral type M4e that is also a Mira variable, with an apparent magnitude ranging between 8.3 and 13.8 over 138 days. Located around 1000 light-years distant, it shines with a luminosity 444 times that of the Sun and has a surface temperature of 3141 K. The Astronomical Society of Southern Africa in 2003 reported that observations of R Microscopii were urgently needed as data on its light curve was incomplete.


59 Arietis

59 Arietis is a star in the northern constellation of Aries. "59 Arietis" is the Flamsteed designation. It is dimly visible to the naked eye with an apparent visual magnitude of 5.91. Based upon an annual parallax shift of , it is located approximately distant from the Sun. The star is moving closer to the Earth with a heliocentric radial velocity of −4.7 km/s.
The spectrum of this object is that of a subgiant star with a stellar classification of G7 IV, which would suggest it has exhausted the supply of hydrogen at its core and has begun to evolve into a giant star. It is around 1.7 billion years old with a projected rotational velocity of 1.8 km/s. The star has nearly double the mass of the Sun and almost six times the Sun's radius. It is radiating 20 times the luminosity of the Sun from its photosphere at an effective temperature of 5,044 K.


Lambda Cephei

Lambda Cephei (λ Cephei) is a fifth magnitude blue supergiant star in the constellation Cepheus, one of the hottest and most luminous visible to the naked eye.
Characteristics.
It is a hot O6.5 supergiant star at a distance of approximately 1,980 light years, whose absolute brightness around half a million times the Sun. Its radius is around 20 times that of the latter, with a mass that has been estimated to be between 45 and 60 solar masses.
Lambda Cephei turns around its axis in less than three days compared to the 24.47 days that the Sun needs to complete a full rotation and seems to be single, with no companions. Its ultimate fate is to explode as a supernova leaving behind a neutron star or perhaps a black hole.
Lambda Cephei is also a runaway star that seems to have been expelled of the stellar association Cepheus OB3, that lies at 2,800 light-years, roughly 2,5 million years ago. Its motion through the interstellar medium is producing a shockwave in front of the gases that surround it and in the direction towards it moves.


24 Cephei

24 Cephei is a single, yellow-hued star in the northern circumpolar constellation of Cepheus. With an apparent visual magnitude of 4.79, it is faintly visible to the naked eye. The distance to this star, based upon an annual parallax shift of , is around 388 light years. It is moving closer with a heliocentric radial velocity of −17 km/s.
Keenan and McNeil (1989) listed a stellar classification of G7 II-III for 24 Cep, matching the spectrum of an evolved G-type star with blended features of a bright giant and a giant star. Older sources list a class of G8 III, which would suggest an ordinary giant star. At the age of 234 million years, it has an estimated 3.5 times the mass of the Sun and has expanded to about 13 times the Sun's radius. The star is radiating 199 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,023 K. These coordinates are a source of X-ray emission.


BC Canis Minoris

BC Canis Minoris is a variable star in the equatorial constellation of Canis Minor. It has a reddish hue and is just barely visible to the naked eye with an apparent visual magnitude that fluctuates around 6.30. The distance to this object is approximately 520 light years based on parallax, but it is drifting closer with a radial velocity of −67 km/s.
This is an aging red giant star currently on the asymptotic giant branch with a stellar classification of M4/5III. It is a semi-regular variable of subtype SRb with measured pulsation periods of 27.7, 143.3 and 208.3 days, and an average visual magnitude of 6.30. With the supply of hydrogen at its core exhausted, it has cooled and expanded off the main sequence and now has around 60 times the girth of the Sun. On average, the star is radiating about 497 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,507 K.


NGC 2242

NGC 2242 is a planetary nebula in the constellation Auriga. It was discovered by Lewis A. Swift on November 24, 1886, and was thought to be a galaxy until a study published in 1987 showed it to be a planetary nebula. The nebula is located about 6,500 light-years away, and about 1,600 light-years above the galactic plane.


WASP-64

WASP-64 is a star about 1200 light-years away. It is a G7 class main-sequence star, orbited by a planet WASP-64b. It is younger than the Sun at 3.6 billion years, and it has a metal abundance similar to the Sun. The star is rotating rapidly, being spun up by the giant planet in a close orbit.
WASP-64 was named "Atakoraka" in 2019 after the Atacora, the largest mountain range in Togo. An imaging survey in 2017 failed to find any stellar companions.
Planetary system.
A transiting hot Jupiter exoplanet orbiting WASP-64 was discovered by WASP in 2012. The planetary equilibrium temperature is 1672 K, while the measured dayside temperature is hotter at 1989 K. Due to the close proximity of the planet to the parent star, orbital decay of WASP-64b, along with HATS-2, may be detectable in the near future. WASP-64b was named "Agouto" (after Mount Agou, the highest point of Togo which lies within the Atacora chain) in 2019 by amateur astronomers from Togo as part of the NameExoWorlds contest.


WASP-52

WASP-52 is a K-type main-sequence star about 570 light-years away. It is older than the Sun at billion years, but it has a similar fraction of heavy elements.
The star has prominent starspot activity, with 3% to 14% of the stellar surface covered by areas 575 K cooler than the rest of the photosphere.
A multiplicity survey in 2015 did not detect any stellar companions. The star was named Anadolu in 2019 by Turkish astronomers as part of the "nameexoworlds" contest.
Planetary system.
In 2012 a transiting hot Jupiter planet, WASP-52b, was detected in a tight, circular orbit. The planet was named Gokturk by Turkish astronomers in December 2019. Its equilibrium temperature is and its orbit is well aligned with the equatorial plane of the star, the misalignment being 5.47°.
A transmission spectrum taken in 2020 has revealed the presence of H, Na and K, although the Na and K lines may be attributable to volcanically active moons of the gas giant, not the planet itself. The atmosphere has no high winds and relatively low-lying clouds, indicating it is not significantly enriched by heavy elements. No signs of the planetary atmosphere escaping to space were detected.


List of stars in Octans

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


NGC 6670

NGC 6670 is a pair of interacting galaxies within the Draco constellation, which lie around 401 million light-years from Earth. Its shape resembles a leaping dolphin. NGC 6670 was discovered by Lewis A. Swift on July 31, 1886. NGC 6670 is a combination of two colliding disc galaxies which are known as NGC 6670E and NGC 6670W. The galaxy is 100 billion times brighter than our Sun. The galaxies have already collided once before and they are now moving towards each other again nearing a second collision. Its apparent magnitude is 14.3, its size is 1.0 arc minutes.
NGC 6670E.
NGC 6670E (also known as NGC 6670-1 and NGC 6670B) is a disc galaxy on the north-eastern side of NGC 6670. It has mostly been destroyed by its collision with NGC 6670W. It has bright nuclear region with a luminosity of 18 L⊙/Mbol due to a large amount of star formation. Its star formation efficiency is at least four times higher than the Milky Way disc, and is approaching the starburst phase. This large amount of star formation is likely to be caused by its collision with NGC 6670W. To the south-east of the nucleus there is a bright and fuzzy area caused by dust extinction or a large concentration of blue stars. NGC 6670E is in-front of NGC 6670W and they are moving towards each other. The movement of the H I region of this galaxy has been disrupted by its collision with NGC 6670W.
NGC 6670W.
NGC 6670W (also known as NGC 6670-2 and NGC 6670A) is a disc galaxy on the south-western side of NGC 6670. It forms the larger part of NGC 6670. It has remained mostly intact after its collision with NGC 6670E. Its nuclear region is slightly dimmer than NGC 6670E, being measured at 11 L⊙/Mbol, but this number still indicates a higher than normal level of star production. Both the western and eastern sides of the disc are significantly curved. The H I region of NGC 6670W is a rotating ring. The western end of the galaxy has a stronger radio continuum peak indicating that it may be a recent star forming region.


HD 23079

HD 23079 is a star in the southern constellation of Reticulum. Since the star has an apparent visual magnitude of 7.12, it is not visible to the naked eye, but at least in binoculars it should be easily visible. Parallax measurements give a distance estimate of 109 light years from the Sun. it is slowly drifting further away with a radial velocity of +0.65 km/s.
This object is an inactive F-type main sequence star with a stellar classification of F9.5V; in between F8 and G0. This indicates it is generating energy through core hydrogen fusion. The star is similar to the Sun, but is slightly hotter and more massive. It is about 5.1 billion years old and it is spinning slowly with a projected rotational velocity of 1.3 km/s. The metallicity of this star is below solar, meaning the abundance of elements other than hydrogen and helium is lower than in the Sun.
The star HD 23079 is named Tupi. The name was selected in the NameExoWorlds campaigns by Brazil during the 100th anniversary of the IAU. The star is named after the Tupi people, a indigenous group.
Planetary system.
In October 2001, a giant planet orbiting the star was announced. The orbit of this object is similar to that of Mars, and the presence of such a large planet would have a strong impact on an Earth-like planet in the habitable zone of this Star.


Beta Lyrae

Beta Lyrae (β Lyrae, abbreviated Beta Lyr, β Lyr) officially named Sheliak (Arabic: الشلياق, Romanization: ash-Shiliyāq) (IPA: ), the traditional name of the system, is a multiple star system in the constellation of Lyra. Based on parallax measurements obtained during the Hipparcos mission, it is approximately distant from the Sun.
Although it appears as a single point of light to the naked eye, it actually consists of six components of apparent magnitude 14.3 or brighter. The brightest component, designated Beta Lyrae A, is itself a triple star system, consisting of an eclipsing binary pair (Aa) and a single star (Ab). The binary pair's two components are designated Beta Lyrae Aa1 and Aa2. The additional five components, designated Beta Lyrae B, C, D, E, and F, are currently considered to be single stars.
Nomenclature.
"β Lyrae" (Latinised to "Beta Lyrae") is the system's Bayer designation, established by Johann Bayer in his "Uranometria" of 1603, and denotes that it is the second brightest star in the Lyra constellation. WDS J18501+3322 is a designation in the Washington Double Star Catalog. The designations of the constituents as "Beta Lyrae A", "B" and "C", or alternatively "WDS J18501+3322A", "B" and "C", and additionally "WDS J18501+3322D", "E" and "F", and those of "A's" components - "Beta Lyrae Aa", "Aa1", "Aa2" and "Ab" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Beta Lyrae bore the traditional name "Sheliak" (occasionally "Shelyak" or "Shiliak"), derived from the Arabic الشلياق "šiliyāq" or "Al Shilyāk," one of the names of the constellation of Lyra in Islamic astronomy. 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 "Sheliak" for the component Beta Lyrae Aa1 on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese astronomy, "Tsan Tae" ( (), meaning "Clepsydra Terrace", refers to an asterism consisting of this star, Delta² Lyrae, Gamma Lyrae and Iota Lyrae. Consequently, the Chinese name for Beta Lyrae itself is (, .)
Properties.
Beta Lyrae Aa is a semidetached binary system made up of a stellar class B6-8 primary star and a secondary that is probably also a B-type star. The fainter, less massive star in the system was once the more massive member of the pair, which caused it to evolve away from the main sequence first and become a giant star. Because the pair are in a close orbit, as this star expanded into a giant it filled its Roche lobe and transferred most of its mass over to its companion.
The secondary, now more massive star is surrounded by an accretion disk from this mass transfer, with bipolar, jet-like features projecting perpendicular to the disk. This accretion disk blocks humans' view of the secondary star, lowering its apparent luminosity and making it difficult for astronomers to pinpoint what its stellar type is. The amount of mass being transferred between the two stars is about solar masses per year, or the equivalent of the Sun's mass every 50,000 years, which results in an increase in orbital period of about 19 seconds each year. The spectrum of Beta Lyrae shows emission lines produced by the accretion disc. The disc produces around 20% of the brightness of the system.
In 2006, an adaptive optics survey detected a possible third companion, Beta Lyrae Ab. It was detected at 0.54" angular separation with a differential magnitude of +4.53. The difference in magnitudes suggests its spectral class is in the range B2-B5 V. This companion would make Beta Lyrae A a hierarchical triple system.
Variability.
The variable luminosity of this system was discovered in 1784 by the British amateur astronomer John Goodricke. The orbital plane of this system is nearly aligned with the line of sight from the Earth, so the two stars periodically eclipse each other. This causes Beta Lyrae to regularly change its apparent magnitude from +3.2 to +4.4 over an orbital period of 12.9414 days. It forms the prototype of a class of ellipsoidal "contact" eclipsing binaries.
The two components are so close together that they cannot be resolved with optical telescopes, forming a spectroscopic binary. In 2008, the primary star and the accretion disk of the secondary star were resolved and imaged using the CHARA Array interferometer and the Michigan InfraRed Combiner (MIRC) in the near infrared H band (see video below), allowing the orbital elements to be computed for the first time.
In addition to the regular eclipses, the system shows smaller and slower variations in brightness. These are thought to be caused by changes in the accretion disc and are accompanied by variation in the profile and strength of spectral lines, particularly the emission lines. The variations are not regular but have been characterised with a period of 282 days.
Companions.
In addition to Beta Lyrae A, several other companions have been catalogued. β Lyr B, at an angular separation of 45.7", is of spectral type B7V, has an apparent magnitude of +7.2, and can easily be seen with binoculars. It is about 80 times as luminous as the Sun. In 1962 it was identified as spectroscopic binary with a period of 4.348 days, but the 2004 release of the SB9 catalog of Spectroscopic Binary Orbits omitted it, so it is now considered a single star.
The next two brightest components are E and F. β Lyr E is magnitude 10.1v, separation 67", and β Lyr F is magnitude 10.6v, separation 86". Both are chemically peculiar stars; both are catalogued as Ap stars, although component F is sometimes thought to be an Am star.
The Washington Double Star Catalog lists two fainter companions, C and D, at 47" and 64" separation, respectively. Component C has been observed to vary in brightness by over a magnitude, but the type of variability is not known.
Components A, B, and F are thought to be members of a group of stars around β Lyrae, at approximately the same distance and moving together. The others just happen to be in the same line of sight. Analysis of Gaia Data Release 2 astrometry reveals a group of about 100 stars around β Lyrae which share its space motion and are at the same distance. This cluster has been named Gaia 8. The cluster members are all main sequence stars and the lack of a main sequence turnoff means that a precise age cannot be calculated, but the cluster age is estimated at 30 to 100 million years. The average Gaia DR2 parallax for the member stars is .
The Gaia spacecraft has provided these data for the stars listed in the WDS:


MU Cephei


Theta Cephei

Theta Cephei, Latinized from θ Cephei, is a stellar class A7, fourth-magnitude star in the constellation Cepheus. It is a white-hued, single-lined spectroscopic binary system, located about 127 light-years from Earth. The pair have an orbital period of 840.6 days with a low eccentricity of 0.03. Shared with η Cep, this star system has the title Al Kidr.
In Chinese, (), meaning "Celestial Hook", refers to an asterism consisting of 4 Cephei, HD 194298, η Cephei, α Cephei, ξ Cephei, 26 Cephei, ι Cephei and ο Cephei. Consequently, the Chinese name for θ Cephei itself is (, .).


NGC 4976

NGC 4976 is a peculiar elliptical galaxy in the constellation Centaurus. It was detected with a 5" telescope working at 20x magnification by comet hunter Jack Bennett.


NGC 5986

NGC 5986 is a globular cluster of stars in the southern constellation of Lupus, located at a distance of approximately from the Sun. It was discovered by Scottish astronomer James Dunlop on May 10, 1826. John L. E. Dreyer described it as, "a remarkable object, a globular cluster, very bright, large, round, very gradually brighter middle, stars of 13th to 15th magnitude". Its prograde–retrograde orbit through the Milky Way galaxy is considered irregular and highly eccentric. It has a mean heliocentric radial velocity of +100 km/s. The galacto-centric distance is , which puts it in the galaxy's inner halo.
This is relatively massive cluster has been poorly studied, at least as of 2017. It is moderately concentrated, with a core radius of and a projected half-light radius of . The three dimensional half-mass radius is . The cluster has a higher metallicity – what astronomers term the abundance of elements with higher atomic number then helium – compared to most other objects of its type. It may have at least 4–5 different stellar populations with distinct elemental compositions, and there is evidence that it has lost ~60–80% of its original mass.


NGC 5662

NGC 5662 is an open cluster in the constellation Centaurus. It was discovered by Nicolas Louis de Lacaille on May 17, 1752 from South Africa. James Dunlop observed it on July 10, 1826 from Parramatta, Australia and added it to his catalog as No. 342.
It is a rich cluster (Trumpler class II3r), with 295 stars according to Haug (1978) and 280 according with Archinal, Hynes (2003). One of its members, V Centauri, is a cepheid variable. Despite its large distance from the cluster centre, it has high likelihood of being a member of it.
The tidal radius of the cluster is 6.4 - 12.4 parsecs (21 - 40 light years) and represents the average outer limit of NGC 5662, beyond which a star is unlikely to remain gravitationally bound to the cluster core.


Ruprecht 44

Ruprecht 44 is an open cluster in the Milky Way galaxy. It is about 6,600 pc away in the constellation Puppis. Ruprecht 44 is a very young open cluster, only about several million years old.


OGLE2-TR-L9b

OGLE2-TR-L9b is an extrasolar planet discovered by three undergraduate students from Leiden University, Netherlands.
The planet is about 4.5 times as massive as Jupiter and is the first discovered planet orbiting a fast-rotating hot star.
Initially discovered while testing a method for investigating light fluctuations in the OGLE database, the planet's existence was later confirmed by follow-up observations from the ESO's Very Large Telescope in Chile.


GL Virginis

GL Virginis, also known as G 12-30, is a star in the constellation of Virgo. It is a faint red dwarf, like more than 70% of the stars located within 10 parsecs of the Solar System; its magnitude visual magnitude is 13.898, making it impossible to see with the naked eye.
Located 21.1 light years away, GL Virginis has a spectral type of M4.5V and an effective temperature of approximately 3110 K. Its luminosity (emitted in the visible section of the electromagnetic spectrum is only one ten-thousandth compared to the Sun; however, since a significant fraction of its radiation is emitted as invisible infrared light, its bolometric luminosity increases to 0.5% of that of the Sun. Its mass is 12% that of the Sun and its radius is 16% of the Sun. It is a fairly rapid rotator: its rotational velocity is least 17 km/s, which implies that it takes less than half a day to complete a rotation on its axis. The star is emitting a frequent flares, with at least five detected by 2019.
The closest known star system to GL Virginis is Gliese 486, 6.4 light-years away.