Alpha Octantis

Alpha Octantis is a binary star system in the constellation of Octans. The name is Latinized from α Octantis. Despite being labeled the "alpha" star by Johann Bayer in his star atlas "Uranometria", it is not the brightest star in the constellation – that title belongs to Nu Octantis. It is visible to the naked eye as a faint, yellow-white hued point of light with an overall apparent visual magnitude of approximately 5.13. The system is located approximately 148 light years away from the Sun based on parallax,
This is a double-lined spectroscopic binary star which consists of two similar giant stars, each with spectral type F, orbiting each other with a period of just over 9 days and an eccentricity of 0.39. The pair form a Beta Lyrae-type eclipsing binary system, dropping by magnitude 0.04 during the primary eclipse. This system is a bright X-ray source with a luminosity of . The system displays an infrared excess suggesting the presence of two debris disks; the first has a temperature of 450 K and is orbiting at a distance of from its host star, while the second is a much cooler 40 K and orbits 187.8 AU from the system.


Ross 695

Ross 695, also known as Gliese 465, is a red dwarf star in the constellation Corvus. At apparent magnitude 11.27, it is much too faint to be seen with the unaided eye. A small star, it has around 23% the mass and radius of the Sun, but only 0.7% its luminosity. Investigation of its radial velocity failed to find any evidence of a planetary companion.


S Coronae Borealis

S Coronae Borealis (S CrB) is a Mira variable star in the constellation Corona Borealis. Its apparent magnitude varies between 5.8 and 14.1, with a period of 360 days—just under a year. Within the constellation, it lies to the west of Theta Coronae Borealis, and around 1 degree southeast of the eclipsing binary star U Coronae Borealis.
Variability.
S Coronae Borealis was discovered to vary in brightness by German amateur astronomer Karl Ludwig Hencke in 1860. It was classified as a long period variable star as other similar objects were discovered, and later as a Mira variable. The maximum range of variation is from magnitude 5.8 to 14.1 although individual maxima and minima can vary in brightness. The period of 360 days is fairly predictable.
Properties.
S Coronae Borealis is a cool red giant on the asymptotic giant branch (AGB). It pulsates, which causes its radius and temperature to change. One calculation found a temperature range of 2,350 K to 2,600 K, although a more modern calculation gives a temperature of 2,864 K. Similarly a calculation of the varying radius gives although a modern calculation of the radius gives . The bolometric luminosity varies much less than the visual magnitude and is estimated to be . Its parallax has been measured by very-long-baseline interferometry (VLBI), yielding a result of 2.39 ± 0.17 millarcseconds, which converts to a distance of 1300 ± 100 light-years.
The masses of AGB stars are poorly known and cannot be calculated from their physical properties, but they can be estimated using asteroseismology. The pulsations of S Coronae Borealis lead to a mass estimate of 1.34 times that of the Sun.


NGC 396

NGC 396 is a lenticular galaxy located in the constellation Pisces. It was discovered on October 27, 1864 by Albert Marth. It was described by Dreyer as "extremely faint, small, a little extended."


Hasta (nakshatra)


NGC 2768

NGC 2768 is a lenticular galaxy located in the constellation of Ursa Major. It is at a distance of 65 million light years from Earth. NGC 2768 is an example of a Seyfert galaxy, an object with a supermassive black hole at its centre. A dusty structure is encircling the centre of the galaxy, forming a knotted ring around the galaxy's brightly glowing middle. This ring lies perpendicular to the plane of NGC 2768 itself, stretching up and out of the galaxy. The dust in NGC 2768 forms an intricate network of knots and filaments.
In the centre of the galaxy are two tiny, S-shaped symmetric jets. These two flows of material travel outwards from the galactic centre along curved paths, and are masked by the tangle of dark dust lanes that spans the body of the galaxy. These jets are a sign of a very active centre, where lies a supermassive black hole. This speeds up and sucks in gas from the nearby space, creating a stream of material swirling inwards towards the black hole known as an accretion disc. This disk throws off material in very energetic outbursts, creating structures like the jets.
NGC 2768 has had one observed Type Ib supernova, designated SN2000ds, which occurred far from the nuclear region.


BU Canis Minoris

BU Canis Minoris is a binary star system in the equatorial constellation of Canis Minor. It has the "Henry Draper Catalogue" designation of HD 65241, while "BU Canis Minoris" is its variable star designation. The system is a challenge to view with the naked eye, having a peak apparent visual magnitude of 6.42. It is located at a distance of approximately 700 light years from the Sun based on parallax, and is drifting further away with a radial velocity of about +34 km/s.
This pair is a double-lined spectroscopic binary system that forms an Algol-like eclipsing binary. The brightness of the system decreases from 6.44 down to 6.53 during the primary eclipse. It has a stellar classification of A0V, which matches an A-type main-sequence star that is generating energy through hydrogen fusion at its core.


Berkeley 87

Berkeley 87 is an open cluster in a heavily obscured region of the Milky Way in Cygnus. The rare WO type Wolf–Rayet star WR 142 is a member of Berkeley 87.


Trumpler 27

Trumpler 27 is a possible open cluster in the southern constellation Scorpius. If it exists, it is a few thousand light-years away from the Sun, with estimates ranging from 3,900 light-years (1,210 kiloparsecs) to 6,800 light-years (2,100 kiloparsecs) The name refers to Robert Julius Trumpler's catalog of open clusters, published in 1930.
It was originally thought to be young open cluster in the outer edge of the Sagittarius Arm, still surrounded by interstellar matter. The light from the stars is heavily extinguished and reddened by intervening interstellar dust. The light coming from the stars is also significantly polarized. However, a close study in 2012 could not confirm whether the stars truly form a cluster, or if they a close alignment of bright stars.
Several member stars have been studied in closer detail. Star #1 of Trumpler 27 is CD−33°12241, a red supergiant star with a spectral type of M0Ia. Stars #28 and #105 are Wolf-Rayet stars. Star #27, a blue giant star with a spectral type of O8III((f)), may be one of the most luminous stars known, with a bolometric magnitude of −10.5. Star #102 is known as V925 Scorpii or HD 159378, and is a rare yellow supergiant star.


U Herculis

The Bayer designations u Herculis and U Herculis are distinct. Due to , both designations link here. For the star


Eta Serpentis

Eta Serpentis (η Ser, η Serpentis) is a star in the constellation Serpens. In particular, it lies in Serpens Cauda, the snake's tail. The star has an apparent visual magnitude of 3.260, making it visible to the naked eye. Parallax measurements give a distance estimate of from the Earth.
This star is larger than the Sun, with twice the mass and almost six times the radius. The spectrum matches a stellar classification of K0 III-IV, with the luminosity class of III-IV corresponding to an evolved star that lies between the subgiant and giant stages. The expanded outer envelope star is radiating about 19 times the luminosity of the Sun at an effective temperature of 4,890 K. At this temperature, it has an orange hue typical of a K-type star. Eta Serpentis displays solar-like oscillations with a period of 0.09 days.
Eta Serpentis was previously classified as a carbon star, which would have made it the brightest carbon star in the sky, although this classification was since found to be erroneous.
Eta Serpentis is currently 1.6 light years away from Gliese 710.
Name.
In Chinese astronomy, the star is known as (), meaning 'Left Wall of Heavenly Market Enclosure'; the name refers to an asterism that represents eleven old states in China. The leftmost borderline of the enclosure consists of η Serpentis, δ Herculis, λ Herculis, μ Herculis, ο Herculis, 112 Herculis, η Ophiuchi, ζ Aquilae, θ1 Serpentis, ν Ophiuchi and ξ Serpentis. Consequently, the Chinese name for η Serpentis itself is (, "the Eighth Star of Left Wall of Heavenly Market Enclosure", representing the region of Donghai (東海, lit. meaning 'eastern sea'),


Iota Capricorni

Iota Capricorni (ι Cap, ι Capricorni) is a solitary, yellow-hued star in the southern constellation of Capricornus. It can be seen with the naked eye, having an apparent visual magnitude of +4.3. Based upon an annual parallax shift of 16.58 mas as seen from the Earth, the star is located about 197 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.08 due to interstellar dust.
This is an evolved G-type giant star with a stellar classification of G8 III. It is classified as a BY Draconis type variable star. This is a chromospherically-active star with a longitudinal magnetic field strength of and an X-ray luminosity of . The activity and photometric variation of the star allow an estimate of its rotation period as 68 days.
Iota Capricorni has an estimated 2.9 times the mass of the Sun and nearly 11 times the Solar radius. It is 390 million years old and is radiating 83 times the solar luminosity from its chromosphere at an effective temperature of 5,200 K.
Chinese name.
In Chinese, (), meaning "Twelve States", refers to an asterism which represents twelve ancient states in the Spring and Autumn period and the Warring States period, consisting of ι Capricorni, φ Capricorni, 38 Capricorni, 35 Capricorni, 36 Capricorni, χ Capricorni, θ Capricorni, 30 Capricorni, 33 Capricorni, ζ Capricorni, 19 Capricorni, 26 Capricorni, 27 Capricorni, 20 Capricorni, η Capricorni and 21 Capricorni. Consequently, the Chinese name for ι Capricorni itself is (, ), meaning that this star (together with 37 Capricorni) represents the state Dai (or Tae)().


LHS 6343

LHS 6343 is a star system in the northern constellation of Lyra. It appears exceedingly faint with a combined apparent magnitude of 13.435. Based on its stellar properties, the system is thought to be about 119.4 light-years (36.6 parsecs) away.
LHS 6343 is a binary star with two red dwarfs, designated LHS 6343 A and B, respectively. A brown dwarf orbits LHS 6343 A at a close distance, and periodically transits it. The brown dwarf, designated LHS 6343 C, is located within the brown dwarf desert, a zone around stars where very few brown dwarfs have been discovered.
The system was in the field of view of the "Kepler" spacecraft, and was monitored continuously for possible planets transiting the star, although the transits were found to be caused by LHS 6343 C.
Properties.
LHS 6343 is a visual binary. Both stars are red dwarf stars that are much less massive compared to the Sun—the primary is 36% the mass of the Sun and the secondary, 29.2% the mass of the Sun. The two stars have been individually resolved using adaptive optics, showing an angular separation of 0.55″, corresponding to a distance of about 20 astronomical units (AU).
The brown dwarf LHS 6343 C orbits the primary star LHS 6343 A at a distance of only 0.0797 AU every 12.7 days. It is about 5 billion years old, and models suggest the brown dwarf has a surface temperature of 1130 K. The system hierarchy is similar to NLTT 41135, another red dwarf binary with a brown dwarf orbiting one of the stars.
Possible planet.
LHS 6343 may have a massive planet within the system. In 2012, transit-timing variation was analyzed for any possible substellar companions that may be perturbing the brown dwarf from its normal orbit. Such an object would be less massive than Jupiter and its orbital period would be 3.5 to 8 times larger than that of the brown dwarf. However, the hypothetical perturber's existence has not been confirmed and warrants more observations of the system.


Psi Crateris

Psi Crateris, Latinized from ψ Crateris, is the Bayer designation for a visual binary star system in the southern constellation of Crater. It is faintly visible to the naked eye with an apparent visual magnitude of 6.13. According to the Bortle scale, it requires dark suburban or rural skies to view. Based upon an annual parallax shift of 6.5 mas, the system is located approximately 500 light years away from the Sun.
The components in this star system have an orbital period of about 366 years with an eccentricity of 0.43. The angular size of the orbit's semimajor axis is about half an arc second. The primary member, component A, is an ordinary A-type main sequence star with a visual magnitude of 6.24 and a stellar classification of A0 V. It was a candidate λ Boötis star, but this was later rejected when the spectrum was found to be normal. Any peculiarities may have instead resulted from the overlapping spectra of the two stars. The star is radiating about 75 times the solar luminosity from it outer atmosphere at an effective temperature of 9,199 K. The fainter secondary, component B, has a visual magnitude of 8.34 and a class of A3.


Theta Leporis

Theta Leporis, Latinized from θ Leporis, is a solitary, white-hued star in the southern constellation of Lepus. It has an apparent visual magnitude of 4.67, making it bright enough to be viewed with the naked eye. Based upon an annual parallax shift of 18.88 mas as measured from Earth, the system is located roughly 173 light years from the Sun. The star made its closest approach about 1.6 million years ago when it came within of the Sun.
This is an ordinary A-type main-sequence star with a stellar classification of A0 V and an age of about 207 million years. It is rotating rapidly with a projected rotational velocity of 207 km/s. This is giving the star an oblate shape with an equatorial bulge that is an estimated 10% larger than the polar radius. It has an estimated 2.35 times the mass of the Sun and is radiating 41 times the Sun's luminosity from its photosphere at an effective temperature of around 10,453 K.


Xi Cancri

Xi Cancri (ξ Cancri, abbreviated Xi Cnc, ξ Cnc) is a spectroscopic binary star system in the zodiac constellation of Cancer. It is visible to the naked eye with an apparent visual magnitude of +5.15. Based upon parallax measurements obtained during the Hipparcos mission, it is roughly 370 light-years distant from the Sun.
The two components are designated Xi Cancri A (formally named Nahn ) and B.
Nomenclature.
"ξ Cancri" (Latinised to "Xi Cancri") is the system's Bayer designation. The designations of the two components as "Xi Cancri 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).
Xi Cancri together with Lambda Leonis (Alterf) were the Persian "Nahn", "the Nose", and the Coptic "Piautos", "the Eye", both lunar asterisms. "Nahn" was also the name given to Xi Cancri in a 1971 NASA technical memorandum. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog 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 "Nahn" for the component Xi Cancri A on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.
Properties.
At its present distance, the visual magnitude is diminished by an extinction factor of 0.135 due to interstellar dust.
Xi Cancri is a single-lined spectroscopic binary star system with an orbital period of 4.66 years, an eccentricity of 0.06, and a semimajor axis of 0.01 arcseconds. The primary, Xi Cancri A, is a yellow G-type giant with an apparent magnitude of +5.70. Its companion, Xi Cancri B, is of magnitude 6.20.


V429 Geminorum

V429 Geminorum (BD+20°1790) is a young orange dwarf star in the constellation Gemini, located nearly 85 light years away from the Sun. It is a BY Draconis variable, a cool dwarf which varies rapidly in brightness as it rotates.
Description.
The star is young and very active and is a member of the AB Doradus Moving Group. The star has also been studied and monitored by SuperWASP group and found to coincide with the ROSAT source 1RXS J072343.6+202500. The planet candidate was announced in December 2009.
Doubtful planet.
The Keplerian fit of the RV data suggested an orbital solution for a close-in massive planet with an orbital period of 7.7834 days. Moreover, the presence of a close-in massive jovian planet could explain the high level of stellar activity detected. However, further study suggests that this planet may not exist because the radial velocity variations are strongly correlated to stellar activity, suggesting this activity is the cause of the variations. This echoes the similar case of the disproven planet detection around TW Hydrae, which was also found to be due to stellar activity rather than orbital motion.


HR 8768

HR 8768, also known as LN Andromedae, is a formerly suspected variable star in the constellation Andromeda. Located approximately away from Earth, it shines with an apparent visual magnitude 6.41, thus it can be seen by the naked eye under very favourable conditions. Its spectral classification is B2V, meaning that it's a hot main sequence star, emitting light approximately with a blackbody spectrum at an effective temperature of 18,090 K.
Companion.
In the Washington Double Star Catalog HR 8768 has a faint optical companion star with an apparent magnitude of 9.88, from HR 8768. The separation has increased from when it was discovered as a double in 1828. The two stars share the same Hipparcos identifier HIP 113802, and have very similar parallaxes and proper motions.
Variability.
In 1979, the blue magnitude of HR 8768 was reported to vary by about 0.025 every 28 minutes. Such variability was not known for any class of variable, but the position in the Hertzsprung–Russell diagram at the main sequence (low luminosity) end of the same instability strip as the β Cephei stars would make high-overtone radial pulsations the likely cause. Follow-up studies failed to find the same rapid variations, or any significant variations in brightness. However, HR 8768 was added to the General Catalogue of Variable Stars as LN Andromedae.
Analysis of Hipparcos photometry shows variability of about 0.0059 magnitudes with a main period of . The statistical threshold for these variations is at a level which is only met by 0.01% of stars.


Chi Lupi

Chi Lupi (Chi Lup, χ Lupi, χ Lup) is a spectroscopic binary star in the constellation of Lupus. It has an apparent visual magnitude of approximately 3.957. The primary star in the binary is a mercury-manganese star of spectral type B9.5V; the secondary is a metallic-lined star of type A2Vm.
This system is a proper motion member of the Upper Scorpius sub-group in the
Scorpius-Centaurus OB association,
the nearest such co-moving association of massive stars to the Sun.
The Upper Scorpius subgroup contains thousands of stars with an average age of 11 million years old at mean distances of 145 parsecs (470 light years).


Sigma Centauri

Sigma Centauri, Latinized from σ Centauri, is the Bayer designation for a solitary star in the southern constellation of Centaurus. It is visible to the naked eye with an apparent visual magnitude of 3.91. A visual companion at an angular separation of along a position angle of was detected in 2010 using interferometry, but its association with Sigma Centauri remains undetermined as of 2013. The distance to Sigma Centauri, based upon an annual parallax shift of 7.92 mas, is around 412 light years.
This is a B-type main sequence star with a stellar classification of B3 V. It is a helium-rich star, the most massive type of chemically peculiar star. Sigma Centauri has around 6.8 times the mass of the Sun and 4.5 times the Sun's radius. It has a relatively high rate of spin with a projected rotational velocity of 169 km/s, and is around 25 million years old. The star radiates 1,101 times the solar luminosity from its outer atmosphere at an effective temperature of 15,744 K. It is a member of the Lower Centaurus Crux component of the Scorpius–Centaurus Association.


DH Cephei

DH Cephei is a variable binary star system in the northern circumpolar constellation of Cepheus, positioned about two degrees to the east of the star system Delta Cephei. With an apparent visual magnitude of 8.61, it is too faint to be visible without a telescope. Based on parallax measurements, this system is located at a distance of approximately from the Sun. At present it is moving closer to the Earth with a radial velocity of −33 km/s.
This is a double-lined spectroscopic binary system consisting of two near-identical, massive, O-type main sequence stars. Evolutionary tracks place the stars close to the zero age main sequence, with an age of less than two million years. This is a detached binary with a close orbit having a period of 2.11 days, and the orbit is assumed to have circularized. The orbital plane is estimated to be inclined by an angle of to the line of sight from the Earth, which yields mass estimates of 38 and 34 times the mass of the Sun. Although initially suspected to be an eclipsing binary and given a variable star designation, it doesn't appear to be eclipsing. Instead, the system displays ellipsoidal light variations that are caused by tidal distortions.
This system lies at the center of the young open cluster NGC 7380. It is the primary ionizing source for the surrounding H II region designated S142. The pair are a source of X-ray emission, which may be the result of colliding stellar winds. Their measured X-ray luminosity is . The location and rare class of these stars make them an important object for astronomical studies.


NGC 5422

NGC 5422 is a lenticular galaxy located in the constellation Ursa Major. It was discovered on April 14, 1789 by the astronomer William Herschel.
At a distance of about 100 million light-years (30 megaparsecs), NGC 5422 is located within the sparse NGC 5485 group, which is dominated by lenticular galaxies. It has only a single, thick, disk component. Like other galaxies in the group, it has no recent star formation, as its stellar disk is relatively old (about 10 billion years old). Its disk appears similar to the face-on galaxy NGC 6340, but appears edge-on.


Kepler-90i

Kepler-90i (also known by its Kepler Object of Interest designation KOI-351.08) is a super-Earth exoplanet with a radius 1.32 that of Earth, orbiting the early G-type main sequence star Kepler-90 every 14.45 days, discovered by NASA's Kepler spacecraft. It is located about 2,840 light-years (870 parsecs, or nearly km) from Earth in the constellation Draco. The exoplanet is the eighth in the star's multiplanetary system. As of December 2017, Kepler-90 is the star hosting the most exoplanets found. Kepler-90i was found with the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured, and by a newly utilized computer tool, deep learning, a class of machine learning algorithms.
Characteristics.
Mass, radius and temperature.
Kepler-90i is a super-Earth exoplanet with a radius of 1.32 , indicating that it is small enough to be rocky. With an Earth-like composition, Kepler-90i would have a mass of about 2.3 , since its volume is formula_1 times that of Earth's. It has an equilibrium temperature of , similar to the average temperature of Venus.
Host star.
The planet orbits Kepler-90, a G-type main sequence star. The star has a mass of 1.2 and a radius 1.2 . It has a surface temperatures of 6080 K and has an estimated age of around 2 billion years, with considerable uncertainty. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K.
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 14. It is too dim to be seen with the naked eye.
Orbital characteristics.
Kepler-90i orbits its host star about every 14.45 days with a semi-major axis of 0.107 AU.
Due to its very close distance to its host star, it is likely to be tidally locked, meaning that one side permanently faces the star in eternal daylight and the other side permanently faces away from the star in eternal darkness.
Discovery.
In 2009, NASA's "Kepler" spacecraft was observing stars on its photometer, the instrument it uses to detect transit events, in which a planet crosses in front of and dims its host star for a brief and roughly regular period of time. In its last test, "Kepler" observed stars in the Kepler Input Catalog, including Kepler-90; the preliminary light curves were sent to the "Kepler" science team for analysis, who chose obvious planetary companions from the bunch for follow-up at observatories. Discovery of the exoplanet was aided by a newly utilized computer tool, deep learning, a class of machine learning algorithms.


22 Vulpeculae

22 Vulpeculae is a binary star system in the northern constellation Vulpecula. Based on its parallax, it is located some 1,490 light-years away, and it has an apparent magnitude of about 5.176, making it visible to the naked eye. The system is moving closer to the Earth with a heliocentric radial velocity of −23 km/s.
The pair have an orbital period of in what is assumed to be a circular orbit. The primary component is a G-type bright giant. It is over five times as massive as the Sun, and over 77 times as wide. Its companion is a B-type main-sequence star, 3.4 times as massive as the Sun. The stars have an orbit that are oriented in such a way that they periodically eclipse each other, blocking the other star's light. For that, it has been given the variable star designation QS Vulpeculae; "22 Vulpeculae" is the Flamsteed designation.


69 Herculis

69 Herculis is a binary star system in the northern constellation Hercules. It has the Bayer designation e Herculis, while "69 Herculis" is the Flamsteed designation. This object is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 4.63. The distance to this system can be estimated from parallax measurements, which yields a range of 175 light years. It is moving closer to the Earth with a heliocentric radial velocity of −10 km/s.
The magnitude 4.66 primary, designated component A, is an A-type main-sequence star with a stellar classification of A2V. It is 155 million years old with 2.12 times the mass of the Sun. The star is spinning with a projected rotational velocity of 155 km/s, which is creating an equatorial bulge that is 5% larger than the star's polar radius. It is about 2.2 times the size of the Sun and is radiating 37 times the Sun's luminosity from its photosphere at an effective temperature of 9,141 K.
The secondary, component B, is magnitude 8.68 star with an angular separation of from the primary, as of 2008. X-ray emission has been detected from this system. As A-type stars are not expected to be X-ray sources, this emission is most likely coming from the companion.


Zeta Persei

Zeta Persei (ζ Per, ζ Persei) is a star in the northern constellation of Perseus. With an apparent visual magnitude of 2.9, it can be readily seen with the naked eye. Parallax measurements place it at a distance of about from Earth.
Description.
This is a lower luminosity supergiant star with a stellar classification of B1 Ib. This is an enormous star, with an estimated 26–27 times the Sun's radius and 13–16 times the Sun's mass. It has about 47,000 times the luminosity of the Sun and it is radiating this energy at an effective temperature of 20,800 K, giving it the blue-white hue of a B-type star. The spectrum displays anomalously high levels of carbon. Zeta Persei has a strong stellar wind that is expelling times the mass of the Sun per year, or the equivalent of the Sun's mass every 4.3 million years.
Zeta Persei has a 9th magnitude companion at an angular separation of 12.9 arcseconds. The two stars have the same proper motion, so they may be physically associated. If so, they are separated by at least 4,000 Astronomical Units. Zeta Persei is a confirmed member of the Perseus OB2 association (Per OB2), also called the Zeta Persei association, which is a moving group of stars that includes 17 massive, high luminosity members with spectral types of O or B, giving them a blue hue. These stars have a similar trajectory through space, suggesting they originated in the same molecular cloud and are about the same age.
Ambiguity.
Some sources, including Starry Night (planetarium software), an atlas, and a web site attribute the name 'Atik' to Zeta Persei instead of nearby Omicron Persei.


NGC 203

NGC 203 is a lenticular galaxy located approximately 233 million light-years from the Solar System in the constellation Pisces. It was discovered on December 19, 1873 by Ralph Copeland.
The galaxy is also listed as NGC 211 in the New General Catalogue.


Al Thalimain

The traditional star name Al Thalimain refers to two stars in the Aquila constellation:
The name derives from the Arabic term "aθ-θalīmain" meaning "The two ostriches".


Delta Circini

Delta Circini (δ Cir), is a multiple star system located in the constellation Circinus. Delta Circini is also known as HR 5664, and HD 135240. The system has a combined apparent visual magnitude of +5.09, and is located at a distance of 770 pc (2,500ly) from the Sun.
Companions.
δ Circini A is a spectroscopic triple star, although the outer component has been resolved using the VLTI PIONIER instrument. The two inner components form an eclipsing binary system.
δ Circini B is a 13th magnitude companion nearly an arc-second away. It is unclear whether the two are physically associated and little is known about the fainter star although it has been reported to be a G5 main sequence star or giant.
HD 135160 is a 6th magnitude binary Be star that shares a common space motion with δ Circini and is only 4 arc minutes away. The two make a faint naked eye pair.
System properties.
All three components of δ Circini A are hot luminous stars. The brightest is an O8 star just beginning to evolve away from the main sequence. It is in a very close orbit with an O9.5 main sequence star. The two stars are deformed into ellipsoidal shapes and eclipse each other every 3.9 days. The total brightness change is only 0.15 magnitudes.
The third component is a B0.5 main sequence star in a long eccentric orbit around the close pair. It is fainter and cooler than either of the two close stars, yet it is calculated to be more massive than δ Cir A, so it is suspected that it may also be a close binary system.


NGC 7209

NGC 7209 is an open cluster in the constellation Lacerta. It was discovered by William Herschel on 19 October 1787. The cluster lies 3,810 light years away from Earth. It has been suggested that there is another cluster at a distance of 2,100 light years projected in front of a cluster lying at 3,800 light years away, based on the reddening of the cluster, however, further photometric studies of the cluster did not support that claim.
The cluster is made up out of 150 stars with magnitude from 9 to 15 within a tidal radius of 9 parsec (30 light years). From its members, 3 are probably delta Scuti variables. One other member of the cluster is the variable SS Lancertae, a binary star with 14.4 day period whose magnitude stopped varying in the middle of the 20th century. This has been attributed to the presence of a third star with period 679 days, whose perturbations change the line of sight. The nodal cycle is found to be about 600 years, within which occur two ecliptic phases, each lasting about 100 yr.


KK Andromedae

KK Andromedae, also known as HD 9531, is a variable star in the northern constellation of Andromeda. It has an apparent visual magnitude of 5.90, which places it near the lower limit of visibility to the naked eye even under good viewing conditions. An Alpha2 Canum Venaticorum variable, it varies in brightness by 0.012 magnitude every 0.66 days. Based upon an annual parallax shift of as seen from Earth, it is located around 437 light years from the Sun. At that distance, the brightness of the star is diminished by an extinction of 0.26 magnitude due to interstellar dust.
Cowley et al. (1969) assigned this star a stellar classification of B9 IV, which would indicate it is a B-type star in the subgiant stage that has exhausted the hydrogen supply at its core and is expanding. It is a catalogued as an Ap star that displays an abnormal silicon abundance, but has been reported to actually be a helium-weak chemically peculiar star. The star has just over three times the mass of the Sun and about 2.7 times the Sun's radius. It is an estimated 225 million years old and is spinning rapidly with a projected rotational velocity of 163 km/s and a rotation period of . KK And is radiating 91 times the Sun's luminosity from its photosphere at an effective temperature of 11,729 K.


Phi Fornacis

Phi Fornacis is a single star in the southern constellation of Fornax. It has a white hue and is faintly visible to the naked eye with an apparent visual magnitude of 5.13. The distance to this object is approximately 154 light years based on parallax, and it is drifting further away with a radial velocity of +19 km/s.
This is an A-type main-sequence star with a stellar classification of A2.5V. Phi Fornacis is 238 million years old and is spinning with a projected rotational velocity of 117 km/s. It has 2.1 times the mass of the Sun and 1.7 times the Sun's radius. The star is radiating 17 times the luminosity of the Sun from its photosphere at an effective temperature of 9,449 km/s. It displays an infrared excess, suggesting a circumstellar disk of dust is orbiting the star at a distance of with a mean temperature of 100 K.


Chi3 Sagittarii

Chi3 Sagittarii (χ3 Sagittarii) is a solitary, orange-hued star in the zodiac constellation of Sagittarius. It is faintly visible to the naked eye with an apparent visual magnitude of +5.45. Based upon an annual parallax shift of 6.53 mas as seen from Earth, it is located roughly 500 light years from the Sun. It is receding from the Earth with a radial velocity of 39.6 km/s.
This is an evolved, K-type giant star with a stellar classification of K3 III. It is a suspected optical variable star with a magnitude range of 5.42 to 5.46. At infrared wavelengths, it shows large amplitude variation with a period of 505 days. The star has expanded to about 37 times the Sun's radius and is radiating 301 times the solar luminosity from its photosphere at an effective temperature of 4,040 K.


R Leporis

R Leporis (R Lep), sometimes called Hind's Crimson Star, is a well-known variable star in the constellation Lepus, near its border with Eridanus. It is designated "R" in the chart to the right.
It is a carbon star which appears distinctly red. It is named after famous British astronomer J. R. Hind, who observed it in 1845. Its apparent magnitude varies from +5.5 to +11.7 with a period of 418–441 days; recent measurements give a period of 427.07 days. There may be a secondary period of 40 years. R Leporis is too far from earth for its parallax to be measured effectively; Guandalini and Cristallo calculated the luminosity of Mira variables based on their periods. Using a period of 427.07 days, they calculated the bolometric luminosity to be . It was estimated to around 1,350 light-years distant in a 2012 paper, shining with a luminosity approximately 6,689 times that of the Sun and has a surface temperature of 2,980 K.
R Leporis has often been reported as an intense smoky red color, although this is not pronounced when the star is near its maximum brightness. It is reddest when it is dimmest, which occurs every 14.5 months. During these periods it is a candidate for the most-visible reddest star, but this claim is questionable. The red coloration may be caused by carbon in the star's outer atmosphere filtering out the blue part of its visible light spectrum. The star's discoverer, Hind, reported that it appeared "like a drop of blood on a black field."


LHS 2090

LHS 2090 is a red dwarf star of spectral type M6.5V, located in constellation Cancer at 20.8 light-years from Earth.
The star was identified to be a red dwarf at short distance (6 parsecs from Sun) in 2001. As typical for very cool red dwarfs, its spectrum is dominated by molecular water absorption. Stellar metallicity is similar to that of Sun`s.
Radial velocity measurements did not yield any detection of stellar companion or giant planet on orbit around LHS 2090, as in 2018.


List of stars in Orion

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


NGC 7257

NGC 7260 ("NGC 7257") is an intermediate spiral galaxy located in the constellation Aquarius. It is a peculiar galaxy.


Beta Sculptoris

Beta Sculptoris, Latinized from β Sculptoris, is a single, blue-white hued star in the southern constellation of Sculptor. It has an apparent visual magnitude of 4.37, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 18.74 mas as seen from Earth, it is located 174 light years from the Sun.
This is a B-type giant star with a stellar classification of B9.5IIIp(HgMnSi). It belongs to the class of chemically peculiar stars known as a Mercury-Manganese star, showing overabundances of mercury, manganese, and silicon in its spectrum. It is a suspected α2 CVn variable with magnitude variation from 4.35 to 4.39. The star has nearly three times the mass of the Sun and double the Sun's radius. It is radiating 81 times the Sun's luminosity from its photosphere at an effective temperature of 12,110 K.


Alpha Ceti

Alpha Ceti (α Ceti, abbreviated Alpha Cet, α Cet), officially named Menkar , is the second-brightest star in the constellation of Cetus. It is a cool luminous red giant about 250 light years away.
Nomenclature.
"Alpha Ceti" is the star's Bayer designation. It has the traditional name Menkar, deriving from the Arabic word منخر "manħar" "nostril" (of Cetus). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included "Menkar" for this star.
This star, along with γ Cet (Kaffaljidhma), δ Cet, λ Cet (also Menkar), μ Cet, ξ1 Cet and ξ2 Cet were "Al Kaff al Jidhmah", "the Part of a Hand".
In Chinese, (), meaning "Circular Celestial Granary", refers to an asterism consisting of α Ceti, κ1 Ceti, λ Ceti, μ Ceti, ξ1 Ceti, ξ2 Ceti, ν Ceti, γ Ceti, δ Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for α Ceti itself is (, .)
Structure.
Despite having the Bayer designation α Ceti, at visual magnitude 2.54 this star is actually not the brightest star in the constellation Cetus. That honor goes instead to Beta Ceti at magnitude 2.04. Menkar is a red giant with a stellar classification of M1.5 IIIa. It has more than twice the mass of the Sun and, as a giant star has expanded to about 89 times the Sun's radius. The large area of the photosphere means that it is emitting about 1,455 times as much energy as the Sun, even though the effective temperature is only 3,795 K (compared to 5,778 K on the Sun). The relatively low temperature gives Menkar the red hue of an M-type star.
Menkar has evolved from the main sequence after exhausting the hydrogen at its core. It has also exhausted its core helium, becoming an asymptotic giant branch star, and will probably become a highly unstable star like Mira before finally shedding its outer layers and forming a planetary nebula, leaving a relatively large white dwarf remnant. It has been observed to vary in brightness, but only with an amplitude of about one hundredth of a magnitude.
Namesakes.
"Menkar" (AK-123) was a United States Navy Crater class cargo ship named after the star.


NGC 7065

NGC 7065 Is a barred spiral galaxy located about 320 million light-years away in the constellation of Aquarius. NGC 7065 is part of a pair of galaxies that contains the galaxy NGC 7065A. NGC 7065 was discovered by astronomer Albert Marth on August 3, 1864.


48 Librae

48 Librae is a single shell star in the constellation Libra. It is a variable star with the designation FX Lib, ranging in magnitude from 4.74 to 4.96. Based upon an annual parallax shift of as seen from Earth's orbit, it is located around 470 light years from the Sun. It is a candidate member of the Upper Scorpius group of the Scorpius-Centaurus Association, with the former having an age of about 11 million years.
This is a main sequence Be star with a stellar classification of B3 Vsh, although it has been variously classed as B3V, B5IIIp shell He-n, B6p shell, B4III, B3IV:e-shell, and B3 shell by different sources. As is the norm for a shell star, it is spinning very rapidly with a projected rotational velocity of 400 km/s − matching or exceeding 80% of the critical velocity. This is giving the star a pronounced oblate shape with an equatorial bulge that is estimated to be 43% larger than the polar radius. It has six times the mass of the Sun and four times the Sun's radius. The star is radiating 1,100 times the Sun's luminosity from its photosphere at an effective temperature of 7,612 K.
The surrounding gaseous disk stretches out to at least 15 times the star's radius and is nearly aligned with the line of sight from the Earth, having an estimated inclination of . Some time between 1931 and 1935, the disk became active and has remained so since that time, becoming the subject of multiple studies. The unusual asymmetry in its emission lines have led to it being misclassified as a supergiant of type B8 Ia/Ib by SIMBAD and others. This asymmetry displays quasi-periodic behavior of the type found in about a third of all Be stars, with a period of about 10 to 17 years. This variation may arise from the precession of a one-armed density wave in the disk.


Gliese 69

Gliese 69 is a star located in the constellation of Cassiopeia. It has an apparent magnitude of 8.40. Parallax measurements by Hipparcos put it at a distance of 44.3 light-years (13.6 parsecs) away.
Gliese 69 is a K-type main-sequence star that is smaller and less massive than the Sun. It glows with an effective temperature of 4,312 K. It is around 6.9 billion years old, significantly older than the Sun. Gliese 69 is also known by its designations HD 14036 and LHS 1291.
Planetary System.
In 2019 one candidate planet been detected by the radial velocity method.


Alpha Pictoris

Alpha Pictoris (α Pic, α Pictoris) is the brightest star in the southern constellation of Pictor. It has an apparent visual magnitude of 3.27, which is bright enough to be viewed from urban areas in the southern hemisphere. This star is close enough for its distance to be measured using parallax shifts, which yields a value of roughly from the Sun, with a 5% margin of error. Alpha Pictoris has the distinction of being the south pole star of the planet Mercury.
Properties.
With an estimated age of 660 million years, this is a relatively young Lambda Boötis star. The stellar classification of shows this peculiarity, with the kA6 notation indicating weaker than normal calcium K-lines in the spectrum. The 'n' following the main sequence luminosity class of V indicates the absorption lines in the spectrum are broad and nebulous. This is caused by the rapid spin of the star, which has a high projected rotational velocity of 206 km/s. Spectroscopy shows narrow, time-varying absorption features being caused by circumstellar gas moving toward the star. This is not the result of interstellar matter, but a shell of gas along the orbital plane. Alpha Pictoris is categorized as a rapidly rotating shell star that may have recently ejected mass from its outer atmosphere.
Alpha Pictoris is larger than the Sun, with twice the mass and a 60% greater radius. It is radiating 13 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of . At this heat, the star glows with the white hue of an A-type star. The space velocity components of this star in the galactic coordinate system are U = -22, V = -20 and W = -9 km/s.
Data from the Hipparcos mission indicate this may be an unresolved binary system with a companion orbiting at a semimajor axis of around 1 AU, or the same distance that the Earth orbits from the Sun. Alpha Pictoris is an X-ray source, which is unusual for an A-type star since stellar models don't predict them to have magnetic dynamos. This emission may instead be originating from the companion.


Theta Persei

Theta Persei (Theta Per, θ Persei, θ Per) is a star system 37 light years away from Earth, in the constellation Perseus. It is one of the closest naked-eye stars.
The primary star is a yellowish dwarf (main sequence) star of spectral type F8V, which is somewhat larger and brighter than the Sun, but still within the range considered to have the potential for Earth-like planets. There is also a red dwarf companion of spectral type M1.V, orbiting about 250 AU from the primary. It has a Gaia Data Release 2 parallax of , corresponding to a distance of .
An 11th-magnitude star is listed in double-star catalogues as component C of the multiple system. It was away from component A in 2002, although the separation is rapidly increasing as it is a distant background object with a very different proper motion to the other two stars. An unconfirmed companion, possibly a brown dwarf, was reported from θ Persei B in 2010.


62 Aurigae

62 Aurigae is a star located 559 light years away from the Sun in the northern constellation of Auriga. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 6.02. This object is moving further from the Earth with a heliocentric radial velocity of +25 km/s. It is an aging giant star with a stellar classification of K2 III, having exhausted the supply of hydrogen at its core then expanded to 22 times the Sun's radius. 62 Aurigae is radiating 167 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,389 K.


Alpha Lyncis

Alpha Lyncis (α Lyn, α Lyncis) is the brightest star in the northern constellation of Lynx with an apparent magnitude of +3.13. Unusually, it is the only star in the constellation that has a Bayer designation. Based upon parallax measurements, this star is located about from the Earth.
This is a giant star that has exhausted the hydrogen at its core and has evolved away from the main sequence. It has expanded to about 55 times the Sun's radius and it is emitting roughly 673 times the luminosity of the Sun. The estimated effective temperature of the star's outer envelope is 3,882 K, which is lower than the Sun's effective temperature of 5,778 K, and is giving Alpha Lyncis an orange hue that is characteristic of K-type stars.
Alpha Lyncis is a suspected small-amplitude red variable star that changes apparent magnitude from +3.17 up to +3.12. This variability pattern typically occurs in stars that have developed an inert carbon core surrounded by a helium-fusing shell, and suggests that Alpha Lyncis is starting to evolve into a Mira-type variable.


NGC 424

NGC 424 is a spiral galaxy in the constellation of Sculptor. It was discovered on November 30, 1837 by John Herschel.


Kepler-90f

Kepler-90f is an exoplanet orbiting the star Kepler-90, located in the constellation Draco. It was discovered by the "Kepler" telescope in October 2013. It orbits its parent star at only 0.48 astronomical units away, and at its distance it completes an orbit once every 124.91 days.


BX442

BX442 (Q2343-BX442) is a grand design spiral galaxy of type Sc. It has a companion dwarf galaxy. It is the most distant known grand design spiral galaxy in the universe, with a redshift of z=2.1765 ± 0.0001.
Although commonly referred to as the oldest known grand design spiral galaxy in the universe,
it is more accurately the earliest such galaxy known to exist in the universe, with a lookback time (the difference between the age of the universe now and the age of the universe at the time light left the galaxy) of 10.7 billion years in the concordance cosmology. This time estimate means that structure seen in BX442 developed roughly 3 billion years after the Big Bang, 10 kiloparsecs (30,000 ly) in diameter, and has a mass of .
Galaxy.
The spiral morphology of BX442, while similar to many modern-day galaxies, makes it unusual in the young universe. According to study co-author Alice E. Shapley of UCLA:
"The vast majority of old galaxies look like train wrecks. Our first thought was, why is this one so different, and so beautiful?"
The unusual spiral morphology of BX442 was discovered using images obtained from the Hubble Space Telescope by a team of astronomers led by David R. Law of the University of Toronto.
While the Hubble image suggested the galaxy's spiral structure however, it didn't conclusively prove that the galaxy rotated like modern-day spiral galaxies. The team therefore used an integral-field spectrograph called OSIRIS (OH-Suppressing Infrared Imaging Spectrograph) at the W.M. Keck
Observatory in Hawaii to confirm their discovery. In combination with a laser-guide-star adaptive optics system which corrects for distortions of incoming light caused by the Earth's turbulent atmosphere, the astronomers were able to sample the light from different parts of the galaxy. Small Doppler shifts of the light between different samples showed that BX442 was indeed a spiral disk, rotating roughly as fast as the Milky Way Galaxy, but much thicker and forming stars more rapidly.
Not only was BX442 revealed to be a genuine spiral galaxy, but part of a sub-class known as 'grand-design' spirals. Most spiral galaxies have subtler features and the arms of the spiral are not necessarily well-defined. A grand design spiral galaxy has very clearly well-formed and distinct arms that significantly stretch out around the galaxy center. Of all spiral galaxies, only about 10% of them are classified as a grand design spiral galaxy.
According to lead author David R. Law:
"The fact that this galaxy exists is astounding. Current wisdom holds that such grand-design spiral galaxies simply didn't exist at such an early time in the history of the Universe."
The presence of a dwarf galaxy in the vicinity of BX442 offers a clue as to how the premature spiral structure may have emerged in what would otherwise be a somewhat chaotic lumpy collection of stars, as is the case with most other early galaxies. A recent study of one of the satellite galaxies of the Milky Way, known as the Sagittarius Dwarf Elliptical Galaxy (SagDEG), suggest that SagDEG may have helped generate some the Milky Way's spiral structure when it passed repeatedly through the plane of our galaxy over the past few hundred million years. Similarly, many of the most well-known grand design spiral galaxies (such as the Whirlpool Galaxy) also have nearby companions. A computer simulation has shown that the dwarf companion of BX442 could have had the same effect. However, the chaotic motions of the stars in the youthful BX442 suggest that, if this is the case, the present spiral structure will not be long-lived in cosmic terms, and may have disappeared within a hundred million years or so.


CK Carinae

CK Carinae (CK Car / HD 90382 / SAO 238038) is a variable star in the constellation Carina, the keel of Argo Navis. It is a member of the star association Carina OB1-D, at a distance of around or .
Classified as a semiregular variable star, CK Carinae's brightness varies between apparent magnitudes +7.2 and +8.5 with a period of approximately 525 days. It has a Gaia Data Release 2 parallax of , which implies a distance of around , and is thought to be a member of the Carina OB1-D stellar association which is at a distance of about . An analysis of the distances of apparently-nearby OB stars implies a distance of for CK Carinae. It has an MK spectral classification of M3.5 Iab, with the luminosity class indicating an intermediate luminosity supergiant.
CK Carinae is a red supergiant with an effective temperature of 3,550 K. It is one of the largest stars, with a radius 761 to 1,060 times larger than the sun, which means that if it were in the place of the Sun, its surface would reach beyond the asteroid belt, Earth being encompassed within the star. Consequently, CK Carinae is also a luminous star, radiating between 86,000 and 158,000 times as much energy as the sun.


Tau8 Eridani

Tau8 Eridani, Latinized from τ8 Eridani, is a binary star system in the constellation Eridanus. It is visible to the naked eye with a combined apparent visual magnitude of 4.65. The distance to this system can be estimated via the parallax method, yielding a value of around 380 light years.
This is a single-lined spectroscopic binary star system with an orbital period of about 459 days and an eccentricity of 0.18. The primary component is a B-type main sequence star with a stellar classification of B6 V. It is a slowly pulsating B-type star that undergoes radial-velocity variation with a frequency of 1.1569 times per day. The star has about five times the mass of the Sun and shines with 256 times the Sun's luminosity. The outer atmosphere has an effective temperature of 11,858 K and may possess a longitudinal magnetic field with a strength of .


NGC 498

 NGC 498 is a lenticular galaxy located about 260 million light-years away from Earth, in the constellation Pisces. NGC 498 was discovered by astronomer R. J. Mitchell on October 23, 1856.
NGC 498 is a member of the NGC 507 Group which is part of the Perseus-Pisces Supercluster.


TrES-2b

TrES-2b is an extrasolar planet orbiting the star GSC 03549-02811 located 750 light years away from the Solar System. The planet has been identified in 2011 as the darkest known exoplanet, reflecting less than 1% of any light that hits it. The planet's mass and radius indicate that it is a gas giant with a bulk composition similar to that of Jupiter. Unlike Jupiter, but similar to many planets detected around other stars, TrES-2b is located very close to its star, and belongs to the class of planets known as hot Jupiters. This system was within the field of view of the "Kepler" spacecraft.
This planet continues to be studied by other projects and the parameters are being improved continuously. A 2007 study improved stellar and planetary parameters. A 2008 study concluded that the TrES-2 system is a binary star system. This has a significant effect on the values for the stellar and the planetary parameters.
Discovery.
TrES-2b was discovered on August 21, 2006 by the Trans-Atlantic Exoplanet Survey (TrES) by detecting the transit of the planet across its parent star using Sleuth (Palomar Observatory, California) and PSST (Lowell Observatory, Arizona), part of the TrES network of 10–cm telescopes. The discovery was confirmed by the W. M. Keck Observatory on September 8, 2006, by measuring the radial velocity of the star that hosts TrES-2b.
Spin-orbit angle.
In August 2008 more details of the relationship between the parent star and the orbit of the planet were published. The orbit was determined to be tilted by − from the stellar equator. The orbital direction was determined to be in the same direction as the star's rotation (prograde).
The "Kepler" mission.
NASA launched "Kepler" in March 2009. The spacecraft is dedicated to the discovery of extrasolar planets by the transit method from solar orbit. In April 2009 the project released the first light images from the spacecraft, and TrES-2b was one of two objects highlighted in these images. Although TrES-2b is not the only known exoplanet in the field of view of this spacecraft it is the only one identified in the first light images. This object is important for calibration and check-out.
The Kepler mission also managed to detect the mass of the planet from Kepler data alone through the analysis of the light curve of the host star. In addition to detecting the planet directly, the planet was also detected by analysis of the star brightness caused by the gravitational tug of TrES-2b by shape distortion of the host star and by light variations due to Doppler beaming.
Physical characteristics.
Albedo.
The first important result from the Kepler Mission about TrES-2b is an extremely low geometric albedo measured in 2011, making it the darkest known exoplanet. If the entire day–night contrast were due to geometric albedo, it would be 2.53%, but modeling suggests that much of this is dayside emission and the true albedo is much lower. It is estimated to be less than 1% and for best-fit model it is about 0.04%. This makes TrES-2b the darkest known exoplanet, reflecting less light than coal or black acrylic paint. It is not clear why the planet is so dark. One reason could be an absence of reflective clouds such as those which make Jupiter so bright, due to TrES-2b's proximity to its parent star and the consequent high temperature. Another reason could be the presence in the atmosphere of light-absorbing chemicals such as vaporized sodium, potassium, or gaseous titanium oxide; however, Kipping and Spiegel excluded heavy oxides of titanium and vanadium from their models, as it seems unrealistic that condensed, heavy compounds be present in the upper atmosphere. They also note that in general, hot Jupiters are expected to be dark, because "absorption due to the broad wings of the sodium and potassium D lines is thought to dominate their visible spectra", and, apart from that of Kepler-7b (), albedo measurements for hot Jupiters have generally given only upper limits.
Temperature.
The planet is likely to be tidally locked to the parent star. In 2015, the planetary nightside temperature was estimated to be equal to 1885 K.


Regulus

Regulus , designated α Leonis (Latinized to Alpha Leonis, abbreviated Alpha Leo, α Leo), is the brightest object in the constellation Leo and one of the brightest stars in the night sky, lying approximately 79 light years from the Sun. Regulus appears singular, but is actually a quadruple star system composed of four stars that are organized into two pairs. The spectroscopic binary Regulus A consists of a blue-white main-sequence star and its companion, which has not yet been directly observed, but is probably a white dwarf. HD 87884 is separated from Regulus by and is itself a close pair. Regulus, along with five slightly dimmer stars (Zeta Leonis, Mu Leonis, Gamma Leonis, Epsilon Leonis, and Eta Leonis) have collectively been called 'the Sickle', which is an asterism that marks the head of Leo.
Nomenclature.
"α Leonis" (Latinized to "Alpha Leonis") is the star system's Bayer designation. The traditional name "Rēgulus" is Latin for 'prince' or 'little king'. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included "Regulus" for this star. It is now so entered in the IAU Catalog of Star Names.
Observation.
The Regulus system as a whole is the twenty-first brightest star in the night sky with an apparent magnitude of +1.35. The light output is dominated by Regulus A. Regulus B, if seen in isolation, would be a binocular object of magnitude +8.1, and its companion, Regulus C, the faintest of the three stars that has been directly observed, would require a substantial telescope to be seen, at magnitude +13.5. Regulus A is itself a spectroscopic binary; the secondary star has not yet been directly observed as it is much fainter than the primary. The BC pair lies at an angular distance of 177 arc-seconds from Regulus A, making them visible in amateur telescopes.
Regulus is 0.465 degrees from the ecliptic, the closest of the bright stars, and is regularly occulted by the Moon. Occultations by Mercury and Venus are possible but rare, as are occultations by asteroids. Seven other stars which have a Bayer designation are less than 0.9° from the ecliptic (perfected, mean plane of earth's orbit and mean apparent path of the sun) the next brightest of which is δ (Delta) Geminorum, of magnitude +3.53. As Regulus closely aligns to the mean orbits of most significant objects of the solar system and is of many times greater magnitude than its comparators, the system has advanced telescopic use (to study and identify objects which may be its orbit) such as when it is occulted by a known asteroid and in observing the shadowing formed by any intermediate solar system matter, including asteroids.
The last occultation of Regulus by a planet was on July 7, 1959, by Venus. The next will occur on October 1, 2044, also by Venus. Other planets will not occult Regulus over the next few millennia because of their node positions. An occultation of Regulus by the asteroid 166 Rhodope was observed by 12 researchers from Portugal, Spain, Italy, and Greece on October 19, 2005. Differential bending of light was measured to be consistent with general relativity. Regulus was occulted by the asteroid 163 Erigone in the early morning of March 20, 2014. The center of the shadow path passed through New York and eastern Ontario, but no one is known to have seen it, due to cloud cover. The International Occultation Timing Association recorded no observations at all.
Although best seen in the evening in the northern hemisphere's late winter and spring, Regulus appears at some time of night throughout the year except for about a month (depending on ability to compensate for the sun's glare, ideally done so in twilight) on either side of August 22–24, when the Sun overlaps. Thus the star can be viewed the whole night, crossing the sky, in late February. Regulus passes through SOHO's LASCO C3 when the sun overlaps. For most Earth observers, the heliacal rising (pre-sunrise appearance) of Regulus occurs in the first week of September. Every 8 years, Venus near-occults the star system around that time, as on 5 September 2014.
Stellar system.
Regulus is a multiple star system consisting of at least four stars. Regulus A is the dominant star, with a binary companion 177" distant that is thought to be physically related. Regulus D is a 12th magnitude companion at 212", but is an unrelated background object.
Regulus A is a binary star consisting of a blue-white subgiant star of spectral type B8, which is orbited by a star of at least 0.3 solar masses, which is probably a white dwarf. The two stars take approximately 40 days to complete an orbit around their common centre of mass. Given the extremely distorted shape of the primary, the relative orbital motion may be notably altered with respect to the two-body purely Keplerian scenario because of non-negligible long-term orbital perturbations affecting, for example, its orbital period. In other words, Kepler's third law, which holds exactly only for two point-like masses, would no longer be valid for the Regulus system. Regulus A was long thought to be fairly young, only 50 – 100 million years old, calculated by comparing its temperature, luminosity, and mass. The existence of a white dwarf companion would mean that the system is at least 1 billion years old, just to account for the formation of the white dwarf. The discrepancy can be accounted for by a history of mass transfer onto a once-smaller Regulus A.
The primary of Regulus A has about 3.8 times the Sun's mass. It is spinning extremely rapidly, with a rotation period of only 15.9 hours, which causes it to have a highly oblate shape. This results in so-called gravity darkening: the photosphere at Regulus' poles is considerably hotter, and five times brighter per unit surface area, than its equatorial region. The star's surface at the equator rotates at about 320 kilometres per second (199 miles per second), or 96.5% of its critical angular velocity for break-up. It is emitting polarized light because of this.
Regulus BC is 5,000 AU from Regulus A. They share a common proper motion and are thought to orbit each other. Designated Regulus B and Regulus C, the pair has Henry Draper Catalogue number HD 87884. The first is a K2V star, while the second is about M4V. The companion pair has an orbital period of about 600 years with a separation of 2.5" in 1942.
Etymology and cultural associations.
"Rēgulus" is Latin for 'prince' or 'little king'; its Greek equivalent (Latinised) is Basiliscus. It is also known as Qalb al-Asad, from the Arabic قلب الأسد, meaning 'the heart of the lion', a name already attested in the Greek Kardia Leontos whose Latin equivalent is Cor Leōnis. The Arabic phrase is sometimes approximated as Kabelaced. In Chinese it is known as 轩辕十四, the Fourteenth Star of Xuanyuan, the Yellow Emperor. In Indian astronomy, Regulus corresponds to the Nakshatra Magha ("the bountiful").
Babylonians called it "Sharru" ("the King"), and it marked the 15th ecliptic constellation. In India it was known as "Maghā" ("the Mighty"), in Sogdiana "Magh" ("the Great"), in Persia "Miyan" ("the Centre") and also as "Venant", one of the four 'royal stars' of the Persian monarchy. It was one of the fifteen Behenian stars known to medieval astrologers, associated with granite, mugwort, and the kabbalistic symbol .
In the Babylonian MUL.APIN, Regulus is listed as Lugal, meaning king, with co-descriptor, "star of the Lion's breast".


NGC 420

NGC 420 is a lenticular galaxy of type S0 located in the constellation Pisces. It was discovered on September 12, 1784 by William Herschel. It was described by Dreyer as "faint, pretty small, round, brighter middle."


Zeta Microscopii

ζ Microscopii, Latinised as Zeta Microscopii, is a solitary, yellow-white hued star in the southern constellation of Microscopium. It is faintly visible to the naked eye with an apparent visual magnitude of +5.31. Based upon an annual parallax shift of 28.27 mas as seen from the Earth, it is 115 light years from the Sun. The star is moving away from the Sun with a radial velocity of +4.6 km/s.
This is an F-type main-sequence star with a stellar classification of F5 V. This indicates that, at the age of 2.2 billion years, it is still generating energy through hydrogen fusion at its core. It is radiating 7.5 times the Sun's luminosity from its photosphere at an effective temperature of 6,471 K. The star has an estimated 1.4 times the mass of the Sun and is spinning with a moderately high projected rotational velocity of 44.4 km/s.


WASP-57

WASP-57 is a single G-type main-sequence star about 1310 light-years away. WASP-57 is depleted in heavy elements, having 55% of the solar abundance of iron. WASP-57 is much younger than the Sun at 0.957 billion years.
A multiplicity survey in 2015 did not detect any stellar companions to WASP-57.
Planetary system.
In 2012 a transiting hot Jupiter planet b was detected on a tight, circular orbit around WASP-57.
Planetary equilibrium temperature is .


HR 4339

HR 4339 is a single star in the equatorial constellation of Hydra. It was designated as Beta Antliae by Lacaille, and Gould intended to keep it in that constellation. However, the delineating of constellation boundaries by the IAU in 1930 saw it transferred to Hydra. It has a white hue and is just visible to the naked eye with an apparent visual magnitude of 5.79. The distance to this star, as determined from parallax measurements, is approximately 366 light years. It is drifting further away with a radial velocity of +1.3 km/s.
This object is an A-type main-sequence star with a stellar classification of A1V. It is a suspected variable star of unknown type and magnitude. The star has 2.6 times the mass of the Sun and it is spinning with a projected rotational velocity of 73 km/s. It is radiating around 72 times the luminosity of the Sun from its photosphere at an effective temperature of 9,120 K.


Theta Reticuli

Theta Reticuli is double star in southern constellation of Reticulum, located just south of Alpha Reticuli. The pair are visible to the naked eye as a dim, white-hued point of light with a combined apparent visual magnitude of 5.88. They lie at roughly the same distance from the Sun based on parallax, with the primary being around 466 light years away. They also share a similar proper motion, suggesting they may be gravitationally-bound.
The magnitude 6.05 primary, designated component A, has a stellar classification of B9IV, matching a B-type subgiant. It is 166 million years old with 3.4 times the mass of the Sun. The star is radiating 179 times the Sun's luminosity from its photosphere at an effective temperature of 11,967 K.
As of 2015, the magnitude 7.65 secondary, component B, had an angular separation of from the primary along a position angle of 3°. It is most likely a very young main sequence star, and is an Am star with a stellar classification of kA2hA5VmA7. This notation indicates the spectrum displays the K-line of an A2 type star, the hydrogen lines of a cooler A5 star, and the metal lines of an A7 star. This system is a source of X-ray emission, which may be coming from the companion.


HD 60863

HD 60863 is a class B8V (blue main-sequence) star in the constellation Puppis. Its apparent magnitude is 4.65 and it is approximately 222 light years away based on parallax.
In addition to the primary, there are distant companions B, at magnitude 9.13 and separation 36.9", and C, at magnitude 10.44 and separation from B of 43.1".


Lupus-TR-3

Lupus-TR-3 is a dim magnitude 17 K-type main sequence star approximately 8,950 light-years distant in the constellation of Lupus.
Planetary system.
Lupus-TR-3 b is an exoplanet discovered in 2007 by personnel from the Harvard-Smithsonian Center for Astrophysics using the transit method. It has four-fifths the mass of Jupiter, nine-tenths the radius, and has density of 1.4 g/cm³. This planet is a typical "hot Jupiter" as it orbits at 0.0464 AU distance from the star, taking 3.9 days to orbit. It is currently the faintest ground-based detection of a transiting planet.


NGC 286

NGC 286 is a lenticular galaxy in the constellation Cetus. It was discovered on October 2, 1886 by Francis Leavenworth.


XO-5

XO-5 is a yellow dwarf main sequence star located approximately 910 light-years away from Earth in the Lynx constellation. It has a magnitude of about 12 and cannot be seen with the naked eye but is visible through a small telescope.
XO-5 have a suspected red dwarf companion with a temperature 3500 K, on a wide orbit.
Naming.
The star XO-5 is named Absolutno. The name was selected in the NameExoWorlds campaign by the Czech Republic, during the 100th anniversary of the IAU. Absolutno is a fictional miraculous substance in the sci-fi novel Továrna na absolutno (The Factory for the Absolute).
Planetary system.
The exoplanet XO-5b was discovered by the XO Telescope using the transit method in 2008. This planet is classified as a hot jupiter. A search for transit timing variations caused by additional planets was negative.


Kepler-29

Kepler-29 is a Sun-like star in the northern constellation of Cygnus. It is located at the celestial coordinates: Right Ascension , Declination . With an apparent visual magnitude of 15.456, this star is too faint to be seen with the naked eye. It is a solar analog, having a close mass, radius, and temperature as the Sun. Currently the age of the star has not been determined due to its 2780 light-year (850 parsecs) distance. As of 2016 no Jovian exoplanets of 0.9–1.4 have been found at a distance of 5 AU.
Planetary system.
In 2011 an analysis of the first four months of data from the Kepler space telescope detected 1235 planetary candidates two of which orbited this star. Later study of the transit-timing variations of the system lead to the confirmation of both planets. The planetary orbits are lying in Orbital resonance to each other, with orbital period ratio being exactly 7:9.


Pi Aurigae

Pi Aurigae, Latinized from π Aurigae, is the Bayer designation for a single, red-hued star in the northern constellation of Auriga. Located about one degree north of the 2nd magnitude star Beta Aurigae, Pi Aurigae is visible to the naked eye with an apparent visual magnitude of 4.25 Based upon parallax measurements, it is approximately away from Earth. At that distance, the brightness of the star is diminished by 0.54 in magnitude from extinction caused by interstellar gas and dust.
Pi Aurigae is an evolved bright giant star with a stellar classification of M3 II. The measured angular diameter of this star, after correction for limb darkening, is . At the estimated distance of Pi Aurigae, this yields a physical size of about 265 times the radius of the Sun. On average, the star is radiating 6,493 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,388 K. It is classified as a slow irregular variable of type LC and its brightness varies from magnitude +4.24 to +4.34.
References.
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GG Tauri

GG Tauri, often abbreviated as GG Tau, is a quadruple or quintuple star system in the constellation Taurus. At a distance of about 450 light years (140 parsecs) away, it is located within the Taurus-Auriga Star Forming Region. The system comprises two (possibly three) stars orbiting each other in a hierarchical triple system, and another binary star system more distant from the central system.
The system is unusual because it contains two distinct circumstellar disks: one surrounding the entire system, and another surrounding the primary component of the system.
Properties.
GG Tauri consists of four (possibly five) stars, which are T Tauri stars – a class of variable stars that show irregular changes in brightness. These stars are extremely young and more luminous than their main sequence counterparts, because they have not condensed into the normal size yet. The four components of GG Tauri stars are relatively cool K-type or M-type stars, with these spectral types: K7 for GG Tauri Aa, M0.5 for GG Tauri Ab, M5 for GG Tauri Ba, and M7 for GG Tauri Bb; the age of the system is estimated to be 1.5 million years.
A dynamical study of the system found the masses of the four stars to be: for GG Tauri Aa, for GG Tauri Ab, for GG Tauri Ba, and for GG Tauri Bb. At , GG Tauri Bb has a substellar mass and is a brown dwarf. Orbital motion has been detected in the central system, but not in the outer pair (as its separation is too high); a preliminary orbit for GG Tauri A has been calculated.
Interferometric techniques have been used to observe GG Tauri Ab, the lower-mass component of the central system. GG Tauri Ab may actually be a double star system comprising two red dwarfs (Ab1 = M2V, Ab2 = M3V), with a separation of about 4.5 AU. Its orbital period is currently estimated to be around 16 years. This would explain why the GG Tauri Ab's spectrum suggests an unusually low-mass star instead of the higher mass that was measured.
Circumstellar disks.
T Tauri stars are usually surrounded by circumstellar disks. These disks coalesce into protoplanets and then into planets. The inner disk around GG Tauri has a mass of about , or about the mass of Jupiter, at a temperature of about 20 to 30 K. However, because mass is currently accreting into the stars themselves, the inner disk must have been consumed, or another larger, circumstellar disk must have been supplying mass into the smaller disk.
A search for diatomic hydrogen gas near GG Tauri was conducted; H2 gas could be found up to 100 AU away from the center of the system, with significant emission also being detected 30 AU away. This emission was detected where a previous survey found gas streaming from the outer disk to the inner disk, so it was assumed that the emission resulted from mass falling from the inner disk to the outer disk. Observations taken in 2014 showed similar results. Indeed, observations of the circumstellar disk around GG Tauri found "sharply-defined features" around the disk: simulations of GG Tauri's disk indicate that these are likely due to the gravitational forces from the two stellar components.
A "gap" in the larger circumstellar disk has been detected at the three-o'clock position, at a position angle of about 268°. First seen in 2002, it was confirmed to be the result of interstellar material shadowing part of the disk.


Tau Serpentis

The Bayer designation Tau Serpentis (τ Ser / τ Serpentis) is shared by a collection of eight stars, τ1 Serpentis through τ8 Serpentis, in the head of the constellation Serpens. They are distributed within a box of size 40 minutes in right ascension by 3.5° in declination. They are numbered by increasing right ascension:


HR 4699

HR 4699 is a single star in the southern constellation of Corvus. It is orange in hue and is dimly visible to the naked eye with an apparent visual magnitude of +5.14. This star is located at a distance of approximately 201 light years from the Sun based on parallax. It is drifting further away with a radial velocity of +14 km/s, after come to within some four million years ago.
This is an aging giant star with a stellar classification of K0 III, having exhausted the supply of hydrogen at its core then cooled and expanded to almost ten times the Sun's radius. It is nearly two billion years old with 1.76 times the mass of the Sun. The star is radiating 43 times the luminosity of the Sun from its photosphere at an effective temperature of 4,707 K.


Delta Lupi

Delta Lupi (δ Lupi, δ Lup) is a star in the southern circumpolar constellation of Lupus. In traditional Chinese astronomy, it is "the 2nd (star) of the Cavalry Officer" (騎官二). With an apparent visual magnitude of 3.22, it is the fourth-brightest star in the constellation. The distance to this star has been measured using the parallax technique, yielding an estimate of roughly 900 light-years with a 15% margin of error.
The spectrum of this star matches a stellar classification of B1.5 IV, which indicates this star has entered the subgiant stage and is in the process of evolving into a giant star. It is radiating around 10,000 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 23,000 K, giving it a blue-white hue. This star has nearly 12 times the mass of the Sun and is roughly 15 million years old.
Delta Lupi is a Beta Cephei variable star that undergoes periodic pulsations. It has a single period of variability lasting 0.1655 days, or six cycles per day. This is a proper motion member of the Upper-Centaurus Lupus sub-group in the Scorpius-Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.


PV Telescopii

PV Telescopii, also known as HD 168476, is a variable star in the southern constellation of Telescopium. It it too dim to be visible to the naked eye, having an apparent visual magnitude that has been measured varying from 9.24 down to 9.40. The star is the prototype of a class of objects called PV Telescopii variables. It is located at an estimated distance of approximately from the Sun, but is drifting closer with a radial velocity of −169 km/s.
This is an extreme helium star that shows a highly-processed atmosphere. It is a blue-white hued B-type supergiant star with a peculiar spectrum that has "weak hydrogen lines and enhanced lines of He and C". This object may be a late thermal pulse post-AGB star or the result of a merger of two white dwarf stars. The star shows radial velocity changes thought to be due to radial pulsations caused by a strange mode instability. It shows variations over a few days, 8–10 days being typically quoted. Despite a mass thought to be less than the sun, it is actually around 24,000 more luminous.


NGC 659

 NGC 659 is an open cluster in the Cassiopeia constellation. It was discovered by Caroline Herschel in 1783.


NGC 2535

NGC 2535 is an unbarred spiral galaxy exhibiting a weak inner ring structure around the nucleus in the constellation Cancer that is interacting with NGC 2536. The interaction has warped the disk and spiral arms of NGC 2535, producing an elongated structure, visible at ultraviolet wavelengths, that contain many bright, recently formed blue star clusters in addition to enhanced star forming regions around the galaxy center. The two galaxies are listed together in the "Atlas of Peculiar Galaxies" as an example of a spiral galaxy with a high surface brightness companion.


Omicron2 Centauri

Omicron2 Centauri (ο2 Cen, ο2 Centauri) is a star in the constellation Centaurus.
ο2 Centauri is a white A-type supergiant with a mean apparent magnitude of +5.12. It is approximately 5000 light years from Earth. It is classified as an Alpha Cygni type variable star and its brightness varies from magnitude +5.12 to +5.22 with a period of 46.3 days.
In 1996, Kaufer and colleagues calculated Omicron2 Centauri to be around 136,000 times as luminous, 18 times as massive and have 131 times the diameter of the Sun.
ο2 Cen forms a close naked eye pair with ο1 Cen, another 5th magnitude supergiant.


NGC 7040

NGC 7040 Is a spiral galaxy located about 260 million light-years away in the constellation of Equuleus. It has an estimated diameter of 42,600 light-years. NGC 7040 was discovered by astronomer Mark Harrington on August 18, 1882.


Pi Mensae

Pi Mensae (π Men), also known as HD 39091, is a yellow dwarf star in the constellation of Mensa. This star has a high proper motion. The apparent magnitude is 5.67, which can be visible to the naked eye in exceptionally dark, clear skies. It is nearly 60 ly away. The star is slightly larger than the Sun in terms of mass, size, luminosity, temperature, and metallicity and is about 730 million years younger. It hosts two known planets.
Planetary system.
On October 15, 2001, an extrasolar planet was found orbiting the star. Pi Mensae b is one of the most massive planets ever discovered, and has a very eccentric orbit that takes approximately 2,151 days (5.89 years) to complete. Because of its eccentricity, and being a massive brown dwarf that passes through the habitable zone, it would have disrupted the orbits of any Earth-like planets, and possibly thrown them into the star, or out into the interstellar medium.
Incorporating more accurate Hipparcos data yields a mass range for the companion to be anywhere from 10.27 to 29.9 times that of Jupiter, confirming its substellar nature with the upper limit of mass putting it in the brown dwarf range.
The companion b was confirmed to be a brown dwarf with the accurate mass measurement in 2020. Pi Mensae was ranked 100th on the list of top 100 target stars for the planned (but now canceled) Terrestrial Planet Finder mission to search for Earth-like planets.
On September 16, 2018, a preprint was posted to arXiv detailing the discovery of a super-Earth on a 6.27-day orbit around the star, the first exoplanet detection by the Transiting Exoplanet Survey Satellite (TESS) submitted for publication. This was confirmed two days later, where the attention was called that the system is amenable for future planet atmospheric studies.
In 2020, an analysis with Gaia DR2 and Hipparcos astrometry showed that planets b and c are located on orbits mutually inclined by 49°-131° (1 sigma), which causes planet c to not transit most of the time, and acquire large misalignments with its host star's spin axis.
The c is likely formed on wide orbit, and then migrated inward under gravitational influence of the brown dwarf b.


H Scorpii

H Scorpii (H Sco) is a star in the constellation Scorpius. Its apparent magnitude is 4.18. It was initially given the Bayer designation Beta Normae by Lacaille but later moved from Norma to Scorpius.
Located around 343 light-years distant, it shines with a luminosity approximately 576 times that of the Sun and has a surface temperature of 4000 K.


NGC 275

NGC 275 is a barred spiral galaxy located approximately 63 million light-years from the Solar System in the constellation Cetus. It is one of a pair of galaxies, the other being NGC 274. It was discovered on October 9, 1828 by John Herschel.
The galaxy was described as "very faint, small, round, southeastern of 2" by John Dreyer in the New General Catalogue, with the other of the two galaxies being NGC 274.


Mu Arae b

Mu Arae b, often designated HD 160691 b, formally named Quijote , is an extrasolar planet orbiting the star Mu Arae of the constellation Ara.
The planet is at least one and a half times the mass of Jupiter, and its orbital period is 643.25 days. The discovery of this planet was announced on December 12, 2002, and was originally thought to be on a highly eccentric orbit. The latest models of its planetary system, which has four known planets, give a lower eccentricity orbit. Although the planet itself is likely to be a gas giant with no solid surface, the orbital distance of 1.497 astronomical units from its star puts it within the habitable zone of its planetary system. As a result, large satellites, if they exist, of the planet, could potentially support life. However, it may not receive enough ultraviolet light for abiogenesis to proceed. Furthermore, it is not clear that Earth-size moons can actually be formed in the environment around a gas giant planet.
Name.
In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name was Quijote for this planet. The winning name was submitted by the Planetario de Pamplona, Spain. Quijote was the lead character of the novel "El Ingenioso Hidalgo Don Quixote de la Mancha". Although the character's name is more commonly spelled Quixote in English, Quijote is the current Spanish spelling.


GX Velorum

GX Velorum is a solitary variable star in the southern constellation of Vela. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude that fluctuates around 4.99. Based upon parallax measurements, it is located approximately 4,200 light years distant from the Sun, and is drifting further away with a radial velocity of +28 km/s. It may be a member of the Vela OB1 association of co-moving stars.
This object is a massive blue supergiant with a stellar classification of B5 Ia. It is suspected to be an Alpha Cygni-type pulsating variable and ranges in brightness from 4.97 down to 5.04 magnitude. It is losing mass at the rate of , or one solar mass every 2.5 million years. The star is 8.3 million years old with 35 times the mass of the Sun. It has expanded to around 61 times the Sun's radius and is radiating 214,000 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 15,000 K.


Alpha Corvi

Alpha Corvi (α Corvi, abbreviated Alpha Crv, α Crv), also named Alchiba , is an F-type main-sequence star and the fifth-brightest star in the constellation of Corvus. Based on parallax measurements made during the Hipparcos mission, it is approximately 49 light-years from the Sun.
Nomenclature.
"α Corvi" (Latinised to "Alpha Corvi") is the star's Bayer designation.
It bore the traditional names "Al Chiba" (Arabic "ألخبا" "al-xibā" "tent") and "Al Minliar al Ghurab" (Arabic "منقار الغراب" "al-manxar al-ghurab") or "Minkar al Ghurab". The latter appeared in the catalogue of stars in the "Calendarium" of Al Achsasi al Mouakket, which was translated into Latin as "Rostrum Corvi" (beak of the crow). 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 "Alchiba" for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese astronomy, Alchiba is called 右轄, Pinyin: Yòuxiá, meaning "Right Linchpin", because it stands alone in the "Right Linchpin" asterism, Chariot mansion (see: Chinese constellation), 右轄 (Yòuxiá), westernized into "Yew Hea" by R.H. Allen.
Namesake.
 is a former United States Navy ship.
Properties.
Alchiba belongs to the spectral class F1V and has apparent magnitude +4.00. This star exhibits periodic changes in its spectrum over a three-day period, which suggests it is either a spectroscopic binary or (more likely) a pulsating Gamma Doradus-type variable.


California Nebula

The California Nebula (NGC 1499) is an emission nebula located in the constellation Perseus. It is so named because it appears to resemble the outline of the US State of California on long exposure photographs. It is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually. It can be observed with a H"α" filter (isolates the H"α" line at 656 nm) or H"β" filter (isolates the H"β" line at 486 nm) in a rich-field telescope under dark skies. It lies at a distance of about 1,000 light years from Earth. Its fluorescence is due to excitation of the H"β" line in the nebula by the nearby prodigiously energetic O7 star, Xi Persei .
The California Nebula was discovered by E. E. Barnard in 1884.
By coincidence, the California Nebula transits in the zenith in central California as the latitude matches the declination of the object.


Epsilon Cephei

Epsilon Cephei, Latinized from ε Cephei, is a star in the northern constellation of Cepheus. Based upon an annual parallax shift of 38.17 mas as seen from the Earth, it is located about 85 light years from the Sun. The star is visible to the naked eye with an apparent visual magnitude of 4.18.
Properties.
Physical Characteristics.
This is a yellow-white hued, F-type star with a stellar classification of or F0 IV. Thus it may either be an F-type main sequence star showing an abundance excess of strontium, or it could be a more evolved subgiant star. It is a Delta Scuti variable star that cycles between magnitudes 4.15 and 4.21 every 59.388 minutes. The star displays an infrared excess, indicating the presence of a debris disk with a temperature of 65 K orbiting at a radius of 62 AU. This dust has a combined mass equal to 6.6% of the Earth's mass.
Binary.
There is a faint companion star at an angular separation of along a position angle of . This corresponds to a projected physical separation of . The probability of a random star being situated this close to Epsilon Cephei is about one in a million, so it is most likely physically associated. If so, then the debris disk is probably circumbinary. The fact that this companion was not detected during the Hipparcos mission may indicate its orbit has a high eccentricity. The companion star has a K-band magnitude of 7.8 and is probably of class K8–M2.
Naming.
In Chinese, (), meaning "Flying Serpent", refers to an asterism consisting of ε Cephei, α Lacertae, 4 Lacertae, π2 Cygni, π1 Cygni, HD 206267, β Lacertae, σ Cassiopeiae, ρ Cassiopeiae, τ Cassiopeiae, AR Cassiopeiae, 9 Lacertae, 3 Andromedae, 7 Andromedae, 8 Andromedae, λ Andromedae, κ Andromedae, ι Andromedae, and ψ Andromedae. Consequently, the Chinese name for ε Cephei itself is (, )


NGC 6250

NGC 6250 is a young open cluster of stars in the southern constellation of Ara.


Alpha Sagittae

Alpha Sagittae, formally named Sham , is a single star in the northern constellation of Sagitta. "Alpha Sagittae" is the Bayer designation, which is latinized from α Sagittae and abbreviated Alpha Sge or α Sge. It is visible to the naked eye as a yellow-hued star with an apparent visual magnitude of +4.38. Despite the name, this is not the brightest star in the constellation – that distinction belongs to Gamma Sagittae. Based upon parallax measurements, Alpha Sagittae is approximately 382 light-years from the Sun. It is moving further away from the Earth with a heliocentric radial velocity of 1.7 km/s.
This is an evolved bright giant with a stellar classification of G1 II. It is 151 million years old with 4 times the mass of the Sun and has expanded to around 21 times the Sun's radius. It is radiating 340 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,333 K. There is an X-ray source within of these coordinates.
The evolutionary state of Alpha Sagittae is unclear. Its temperature and luminosity place it within the Hertzsprung gap, a region of the H-R diagram where stars more massive than the sun are evolving rapidly away from the main sequence towards becoming red giants. However, the chemical composition of its surface indicates that it has already experienced the first dredge-up of fusion products that occurs soon after a star reaches the red giant branch. It also lies within the Cepheid instability strip, but is not a Cepheid variable. It belongs to a small group of known stars that have been called carbon-deficient red giants and may have experienced binary mass exchanges.
Nomenclature.
This star bore the traditional name "Sham" (or "Alsahm"), which derives from the Arabic word سهم "sahm", meaning "arrow", the name formerly having been applied to the whole constellation. 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 "Sham" for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Left Flag", refers to an asterism consisting of Alpha Sagittae, Beta Sagittae, Delta Sagittae, Zeta Sagittae, Gamma Sagittae, 13 Sagittae, 11 Sagittae, 14 Sagittae and Rho Aquilae. Consequently, the Chinese name for Alpha Sagittae itself is (, ).


Upsilon4 Eridani

Upsilon4 Eridani is a close binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.56. Based upon parallax measurements, the pair are located around from the Sun.
This is a double-lined spectroscopic binary star system, which means that the Doppler-shifted spectral lines of both components can be distinguished. The pair have a circular orbit with a period of five days. The system is composed of two B-type main-sequence stars: one has a stellar classification of B8V and the other B9.5V. Both stars show HgMn peculiarities in their spectrum, and their properties are nearly identical. The spin rate of the two stars is synchronized to their orbital period. It is possible that a nearby K-type star is also related.


M Puppis

The Bayer designations m Puppis and M Puppis are distinct. Due to , both designations link here. For the star


65 Aurigae

65 Aurigae is a binary star system located 252 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 visual magnitude of 5.12. The primary, designated component A, is an aging giant star with a stellar classification of K0 III. It is 3.31 billion years old and has expanded to 13 times the Sun's radius after exhausting the hydrogen at its core. Its companion, component B, is a magnitude 11.7 star located at an angular separation of from the primary, as of 2008. The pair are moving further from the Earth with a heliocentric radial velocity of 22 km/s.


HD 73526

HD 73526 is a star in the southern constellation of Vela. With an apparent visual magnitude of +8.99, it is much too faint to be viewed with the naked eye. The star is located at a distance of approximately 318 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +26 km/s. It is a member of the thin disk population.
The stellar classification of HD 73526 is G6 V, indicating this is a G-type main-sequence star that, like the Sun, it is generating energy through core hydrogen fusion. Based on its properties, it may be starting to evolve off the main sequence. This star has slightly more mass than the Sun and a 53% greater radius. The abundance of iron in its atmosphere suggests the star's metallicity – what astronomers term the abundance of elements with higher atomic number than helium – is 70% greater than in the Sun. It is a much older star with an estimated age of nearly ten billion years, and is spinning slowly with a projected rotational velocity of 1.7 km/s. The star is radiating more than double the luminosity of the Sun from its photosphere at an effective temperature of 5,564 K.
Planetary system.
On June 13 2002, a 2.1 MJ planet HD 73526 b was announced orbiting HD 73526 in an orbit just a little smaller than that of Venus' orbit around the Sun. This planet receives insolation 3.65 times that of Earth or 1.89 times that of Venus. This was a single planet system until 2006 when a 2.3 MJ second planet HD 73526 c was discovered. This planet forms a 2:1 orbital resonance with planet b. Although these are minimum masses as the inclinations of these planets are unknown, orbital stability analysis indicated that orbital inclinations of both planets are likely to be near 90°, making the minimum masses very close to the true masses of the planets.


HD 202206 c

HD 202206 c is an extrasolar planet discovered on November 16, 2004, using long-term observation of a formerly unconfirmed second planet after the discovery of a brown dwarf (first companion) around the star. This was the first circumbinary planet to be found around a main sequence star.
The planet orbits 3.07 times further out and is 85% less massive than the first companion, having a semi-amplitude of only 42 m/s. Its mass is 2.44 times that of Jupiter and its diameter is roughly the same size as Jupiter's. The orbital resonance of the planet orbiting the brown dwarf is 5:1. The eccentricity of the planet is higher than that of all the planets and dwarf planets in the Solar System except Eris, which has an eccentricity of 0.44.


NGC 5823

NGC 5823 (also known as Caldwell 88) is an open cluster in the southern constellation of Circinus, near (and extending across) its border with the constellation Lupus. It was discovered by Scottish astronomer James Dunlop in 1826.