FO Aquarii

FO Aquarii is an intermediate polar star system in the constellation Aquarius. The white dwarf and companion star orbit each other with a period of approximately 4.85 hours. The system is famous for a very strong optical pulsation which occurs every 20.9 minutes, corresponding with the rotational period of the accreting white dwarf. Prior to 2016, the system's long-term optical brightness varied between apparent magnitude 12.7 and 14.2, but in early 2016, it faded to magnitude 15.8 and thereafter began a slow recovery to its normal brightness, behavior which is indicative of a temporary dropoff in the mass-transfer rate between the two stars.


Delta2 Tauri

Delta2 Tauri (δ2 Tauri) is a solitary, white-hued star in the zodiac constellation of Taurus. Based upon an annual parallax shift of 20.21 mas as seen from Earth, it is located roughly 161 light years distant from the Sun. It is separated from δ1 Tauri by 0.3° on the sky and is faintly visible to the naked eye with an apparent visual magnitude of +4.80. The star is considered a member of the Hyades cluster.
At the estimated age of 449 million years, this is an A-type main-sequence star with a stellar classification of A2 Vs, where the 's' suffix indicates narrow (sharp) absorption lines. It has 1.8 times the mass of the Sun and about 1.8 times the Sun's radius. The star is radiating 27 times the Sun's luminosity from its photosphere at an effective temperature of 7,997 K.
δ2 Tauri is a source of X-ray emission with a luminosity of . Since A-type stars are not normally a source of X-rays, this emission may be coming from an unknown companion or from a line of sight source.


57 Persei

57 Persei, or m Persei, is a suspected triple star system in the northern constellation of Perseus. It is at the lower limit of visibility to the naked eye, having a combined apparent visual magnitude of 6.08. The annual parallax shift of 16.90 mas provides a distance estimate of about 193 light years. 57 Persei is moving closer to the Sun with a radial velocity of about −23 km/s and will make perihelion in around 2.6 million years at a distance of roughly .
The primary member, designated component A, is a magnitude 6.18, yellow-white hued F-type main-sequence star with a stellar classification of F0 V, indicating it is generating energy by fusing its core hydrogen. It is an estimated 1.6 billion years old and is spinning with a projected rotational velocity of 90 km/s. The star has 1.3 times the mass of the Sun and is radiating 10.7 times the Sun's luminosity from its photosphere at an effective temperature of around 6,615 K.
An unseen companion has been identified via slight changes to the proper motion of the primary. The third member, component B, is a magnitude 6.87 F-type star at an angular separation of 120.13 arc seconds. This star has a different parallax and space velocity than the primary, so it may just be a wide visual companion. There are three other nearby visual companions that are not associated with the 57 Persei system.


Nu2 Sagittarii

Nu2 Sagittarii (ν2 Sagittarii) is a binary star system in the zodiac constellation of Sagittarius. It is faintly visible to the naked eye, having an apparent visual magnitude of +4.98; it is 0.16 degree north of the ecliptic. The annual parallax shift of 11.91 mas as seen from Earth, indicates this system is roughly 270 light years from the Sun. Nu2 Sagittarii has a high peculiar velocity of and is most likely a runaway star system.
The spectrum of the primary component displays a stellar classification of K1 Ib–II, indicating this is a K-type star with a mixed luminosity class of an evolved bright giant/supergiant star. It is a mild barium star, showing an enhanced abundance of s-process elements in its outer atmosphere. This material was most likely acquired during a previous mass transfer from its now white dwarf companion. The primary has an estimated 1.4 times the mass of the Sun and has expanded to 85 times the Sun's radius.


Officina Typographica

Officina Typographica (Latin for "printing office") was a constellation located east of Sirius and Canis Major, north of Puppis, and south of Monoceros. It was drawn up by Johann Bode and Joseph Jérôme de Lalande in 1798, and included in the former's star atlas "Uranographia" in 1801, honouring the printing press of Johannes Gutenberg. Lalande reported wanting to honour French and German discoveries in the same manner that Nicolas-Louis de Lacaille had done for his new constellations. It was called "Buchdrucker-Werkstatt" by Bode initially, and later "Atelier Typographique" in the 1825 work "Urania's Mirror", "Atelier de l’Imprimeur" by Preyssinger in 1862 and "Antlia Typographiae" in 1888.
The constellation appeared in later star atlases through the 19th century but was rarely used by the end of the century; Richard Hinckley Allen noted its most recent use had been in 1878 in Father Angelo Secchi's planisphere, but stated "it is seldom found in the maps of our day.". The stars were later absorbed into northern Puppis, and remained permanently there after the setting of the constellation boundaries in 1928.


Delta Librae

Delta Librae, Latinized from δ Librae, is a variable star in the constellation Libra. It has the traditional name Zuben Elakribi, a variant of the traditional name of Gamma Librae. With μ Vir it forms one of the Akkadian s "Mulu-izi" (meaning "Man-of-fire").
δ Lib is approximately 300 light years from the Earth and the primary, component A, belongs to the spectral class B9.5V, indicating it is a B-type main-sequence star. It is visible to the naked eye with an apparent visual magnitude of 4.93 and is moving closer to the Sun with a radial velocity of −39 km/s. This is an Algol-like eclipsing binary star system, with a period of 2.3274 days and an eccentricity of 0.07. Its apparent magnitude varies from 4.91m to 5.9m. The secondary is filling its roche lobe and there is evidence of large-scale mass transfer in the past, with the star being more evolved than the primary.
Along with λ Tau, it was one of the first stars on which
rotational line broadening was observed, by Frank Schlesinger in 1911.


42 Orionis

42 Orionis is a class B1V (blue main-sequence) star in the constellation Orion. Its apparent magnitude is 4.59 and it is approximately 900 light years away based on parallax.
The primary star, Aa, has one spectroscopic companion Ab of magnitude 6.3 and separation 0.16", and a more distant companion B of 7.5 magnitude at 1.6" separation.
c Orionis is surrounded by NGC 1977 one of a smaller fainter group of named nebulae just north of the Orion Nebula. c Ori is the star which excites and illuminates NGC 1977.


Theta Coronae Borealis

Theta Coronae Borealis, Latinized from θ Coronae Borealis, is a binary star system in the constellation Corona Borealis. It shines with a combined apparent visual magnitude (V band) of 4.13. There are two components: Theta Coronae Borealis A is of apparent magnitude 4.16, while Theta Coronae Borealis B lies around 1 arcsecond distant and has an apparent magnitude of 6.29. The system is located around 375 light-years from Earth, as estimated from its parallax of 8.69 milliarcseconds. It is estimated to be 85 million years old, with the primary star expected to remain on the main sequence burning its core hydrogen for another 75 million years and the secondary around 500 million years. Both stars will cool and expand once their core hydrogen is exhausted, becoming red giants.
The brighter component, Theta Coronae Borealis A, is a blue-white star that spins extremely rapidly—at a rate of around 393 km per second. This rapid spinning is thought to be the cause of a gaseous disk that surrounds the star: such stars are known as Be shell stars, recognizable because the gas radiates emission lines that give a characteristic pattern in the star's spectrum. Of spectral type B6Vnn, Theta Coronae Borealis A is around six times as massive as the Sun and has four times the diameter. It has a surface temperature of around 14910 K. In 1970, it faded by 0.7 magnitude, becoming 50% fainter. The cause for this is unknown, but thought possibly due to ejection of dust that obscured the star's light.
Theta Coronae Borealis B is a white main sequence star of spectral type A2V that is around 2.5 times as massive as the Sun and located 86 astronomical units from the primary star, the two stars taking an estimated 300 years to orbit around a common centre of gravity.


A Centauri

A Centauri is a single star in the southern constellation of Centaurus. It is a blue-white in hue and is faintly visible to the naked eye with an apparent visual magnitude of +4.62. The star is located at a distance of approximately 430 light years from the Sun based on stellar parallax. It appears to be drifting further away with a radial velocity of around +6 km/s.
This is a rapidly rotating Be star, showing an emission line spectrum on top of the normal absorption spectrum of the star, due to a circumstellar disk of ejected matter. It doesn't show any absorption lines from the disk. It is a B-type main-sequence star with a stellar classification of B9V.


List of star names in Lepus

This is the list of the proper names for the stars in the constellation Lepus. (Used in modern Western astronomy and uranography only).


Winnowing Basket (Chinese constellation)

The Winnowing Basket mansion (箕宿, pinyin: Jī Xiù) is one of the Twenty-Eight Mansions of the Chinese constellations. It is one of the eastern mansions of the Azure Dragon.


Rho Scorpii

Rho Scorpii (ρ Scorpii, abbreviated Rho Sco, ρ Sco) is a double star in the constellation of Scorpius. It has an apparent visual magnitude of +3.87, which is bright enough to be seen with the naked eye. Based upon parallax measurements, it is located approximately 472 light years from the Sun. At that distance, the visual magnitude of the system is reduced by 0.07 due to extinction from interstellar dust. It is a member of the Upper Scorpius OB association.
It has two components, designated Rho Scorpii A and B. Rho Scorpii A is itself a single-lined spectroscopic binary whose components are designated Rho Scorpii Aa (formally named Iklil , traditionally the name for several neighboring stars) and Ab.
Nomenclature.
"ρ Scorpii" (Latinised to "Rho Scorpii") is the system's Bayer designation. The designations of the three constituents as "Rho Scorpii A" and "B", and those of "A's" components - "Rho Scorpii Aa" and "Ab" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Rho Scorpii was likely part of the Arabic lunar mansion of Iklil (الإكليل "al-ʼiklīl") "the crown (of the forehead)"), along with Beta, Delta, Pi and possibly Nu Scorpii.
The corresponding asterism in Chinese astronomy, (), meaning "Room", consists of Rho Scorpii, Pi Scorpii, Delta Scorpii, Beta¹ Scorpii and Beta² Scorpii. Consequently, the Chinese name for ρ Scorpii itself is (), "the Second Star of Room".
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 "Iklil" for the component Rho Scorpii Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
Properties.
Rho Scorpii A displays the spectrum of blue-white B-type subgiant with a stellar classification of B2 IV. It has an estimated mass nearly 8 times that of the Sun's and shines with 3,432 times the Sun's luminosity. The two constituent stars orbit each other with a period of 4 days and an eccentricity of 0.27.
Rho Scorpii B is a magnitude 12.80 visual companion that lies at an angular separation of 38.40 arcseconds along a position angle of 95°, as of the year 2000.


Sigma Hydrae

Sigma Hydrae (σ Hydrae, abbreviated Sigma Hya, σ Hya), also named Minchir , is a solitary star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.48. The estimated distance to this star from the Sun, based upon an annual parallax shift of 8.75 mas, is around 370 light-years. At that distance, the visual magnitude of the star is diminished by an interstellar extinction factor of 0.16, due to intervening dust.
Nomenclature.
"σ Hydrae" (Latinised to "Sigma Hydrae") is the system's Bayer designation.
It bore the traditional name "Minchir", appearing as "Minchir es-schudscha" in Bode's large star atlas, "Uranographia". The name which derived from the Arabic appelationمنخر الشجاع "minkhar ash-shujāʽ" "the nostril brave one" (the hydra) for this star. The name is erroneously spelt as "Al Minliar al Shuja" in the Yale "Bright Star Catalogue". In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name "Minchir" for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
This star, along with Delta Hydrae (Lisan al Shudja), Epsilon Hydrae, Zeta Hydrae, Eta Hydrae and Rho Hydrae, were Ulug Beg's "Min al Azʽal", "Belonging to the Uninhabited Spot". (According to a 1971 NASA memorandum, "Min al Azʽal" or "Minazal" were the title for five stars : Delta Hydrae as "Minazal I", Eta Hydrae as "Minazal II", Epsilon Hydrae as "Minazal III", Rho Hydrae as "Minazal IV" and Zeta Hydrae as "Minazal V".)
In Chinese, (), meaning "Willow (asterism)", refers to an asterism consisting of Sigma Hydrae, Delta Hydrae, Eta Hydrae, Rho Hydrae, Epsilon Hydrae, Zeta Hydrae, Omega Hydrae and Theta Hydrae. Consequently, Sigma Hydrae itself is known as (, ).
The people of Groote Eylandt, used the name "Unwala" ("The Crab") for the star cluster including this star, Delta Hydrae (Lisan al Shudja), Epsilon Hydrae, Zeta Hydrae, Eta Hydrae and Rho Hydrae.
Properties.
This is an evolved K-type giant star with a stellar classification of K2 III. The measured angular diameter of this star, after correction for limb darkening, is . At its estimated distance, this yields a physical size of about 27.6 times the radius of the Sun. It has about three times the mass of the Sun and radiates 295 times the solar luminosity from its outer atmosphere at an effective temperature of 4,491 K. Sigma Hydrae is around 430 million years old.
References.
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Zeta Scorpii

The Bayer designation Zeta Scorpii (ζ Sco, ζ Scorpii) is shared by two stars in the constellation Scorpius:
They are separated by 7 arc minutes on the sky. The stars are not physically related as they are at greatly different distances from the Earth.
All of them were member of asterism 尾 (Wěi), "Tail", "Tail" mansion.


NGC 4084

NGC 4084 is an elliptical galaxy located 315 million light-years away in the constellation Coma Berenices. NGC 4084 was discovered by astronomer Heinrich d'Arrest on April 26, 1865. NGC 4084 is an isolated member of the Coma Supercluster and is classified as a LINER galaxy.


Revati (nakshatra)

Revathi is the Hindu name for Zeta Piscium, a star on the edge of the Pisces zodiac constellation. In Hindu sidereal astronomy this star is identified as the First Point of Aries, i.e. when the Sun crosses this star, a new solar year begins.
Astrology.
Revati (Devanagari: रेवती) is the twenty-seventh nakshatra in Hindu astrology (or the 28th, if Abhijit is counted) corresponding to ζ Piscium.
It is ruled by Puṣan,one of the 12 Ādityas. According to the beliefs of traditional electional astrology, Revati is a sweet or delicate nakshatra, meaning that while Revati has the most influence, it is best to begin working on things of physical beauty like music and jewellery .
Revati is symbolized by fish (often a pair of fish). It is also associated with the sea.
Traditional Hindu given names are determined by which pada (quarter) of a nakshatra the Ascendant/Lagna was in at the time of birth. In the case of Revati, the given name would begin with the following syllables:


List of stars in Eridanus

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


HD 92036

HD 92036 is a single star in the equatorial constellation of Hydra. Its apparent magnitude is 4.87. This is an aging red giant star on the asymptotic giant branch with a stellar classification of M1III:Ba0.5.


HD 224635

HD 224635 and HD 224636 is a pair of stars comprising a binary star system in the constellation Andromeda. They are located approximately 94 light years away and they orbit each other every 717 years.
The primary star is HD 224635, a magnitude 6.46 star (making it visible by the naked eye under very favourable conditions) with a spectral type F8 that is 1.19 times more massive than the Sun.
The secondary star is the slightly fainter HD 224636, with an apparent visual magnitude of 6.72, a spectral type G1, and 1.13 times more massive than the Sun.


NGC 5579

NGC 5579 is an intermediate spiral galaxy in the constellation Boötes.


3C 299

3C 299 is a radio galaxy/quasar located in the constellation Boötes.


Eta Lupi

η Lupi, often Latinised as Eta Lupi, is a probable triple star system in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 3.41. Based upon an annual parallax shift of 27.80 mas as seen from Earth, it is located around distant from the Sun. It is a member of the Upper Centaurus Lupus subgroup of the nearby Sco OB2 association.
The inner pair in this triple system has an estimated orbital period of around 27,000 years. As of 2013, they had an angular separation of 15.0 arc seconds along a position angle of 19°. The primary star, component A, is an evolving A-type subgiant star with a stellar classification of B2 IV. It has used up the supply of hydrogen at its core and has begun to expand off the main-sequence.
The secondary, component B, is a chemically peculiar A-type main sequence star with a class of A5 Vp and an estimated mass 2.10 times that of the Sun. The outer member, component C, has an orbital period of around half a million years. As of 2007, it had an angular separation of 115.8 arc seconds along a position angle of 248° from the primary. It is an F-type main sequence star with a classification of F5 V and an estimated 1.29 times the Sun's mass.


39 Cygni

39 Cygni is a binary star system near the southern border of the northern constellation of Cygnus, approximately 250 light years away from Earth. It is visible to the naked eye as an orange-hued star with an apparent visual magnitude of 4.43. The system is moving closer to the Sun with a heliocentric radial velocity of −17 km/s.
This is a single-lined spectroscopic binary with an orbital period of about and an eccentricity of 0.5. The projected semi-major axis of the primary star's orbit is , providing a lower bound on the separation of the stars. The system is around four billion years old.
The visible component is an evolved K-type giant star with a stellar classification of ; the suffix notation indicates a mild underabundance of iron in the spectrum. It is probably on the horizontal branch, fusing helium in its core, but may be on the red giant branch fusing hydrogen in a shell around an insert helium core. It has 1.3 times the mass of the Sun and has expanded to 22 times the Sun's radius. The star is radiating 186 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,259 K.
The unseen secondary component is most probably a main sequence star with a type between F and mid-K, although it may be a white dwarf instead. Its mass is at least 0.7–1.0 times the mass of the Sun.


HD 88955

HD 88955 is a single, white-hued star in the southern constellation of Vela. It can be viewed with the naked eye, having an apparent visual magnitude of 3.85. The distance to HD 88955 can be determined from its annual parallax shift of , which yields a separation of 100 light years from the Sun. It is moving further from the Earth with a heliocentric radial velocity of +7 km/s. Bayesian analysis suggests HD 88955 is a member of the Argus Association, a group of co-moving stars usually associated with the IC 2391 open cluster.
This is an A-type main-sequence star with a stellar classification of A2 V. It is about 410 million years old with a projected rotational velocity of 100 km/s. The star has 2.17 times the mass of the Sun and 2.11 times the Sun's radius. It is radiating 23 times the Sun's luminosity from its photosphere at an effective temperature of 9,451 K. An infrared excess has been detected from HD 88955, which analysis suggests is a debris disc with a mean temperature of orbiting the host star at an average distance of .


RS Coronae Borealis

RS Coronae Borealis is a semiregular variable star located in the constellation Corona Borealis with a parallax of 2.93mas being a distance of . It varies between magnitudes 8.7 to 11.6 over 332 days. It is unusual in that it is a red star with a high proper motion (greater than 50 milliarcseconds a year). Located around 1072 light-years distant, it shines with a luminosity approximately 1839 times that of the Sun and has a surface temperature of 3340 K.


HD 87822

HD 87822 is a binary star in the northern constellation of Leo Minor. The pair orbit each other with a period of about 18 years.


HD 50554

HD 50554 is a star approximately away in the constellation Gemini.
Star.
HD 50554 is a yellow-white main-sequence star [F8V] that currently fuse hydrogen in its core. Since the star is 7th magnitude, it is not visible to the unaided eye, but with binoculars or a telescope, it should be easy to see this star. The age of the star is only 10 million years older than our Sun. It is a population I star with metallicity of –0.07 dex [Fe/H] or 85% as much metals as the Sun.
Planetary system.
In 2001, a giant planet was announced by the European Southern Observatory, who used the radial velocity method. The discovery was confirmed in 2002 using observations from the lick and keck telescopes.


NGC 6287

NGC 6287 is a globular cluster located in the constellation Ophiuchus. It is designated as VII in the galaxy morphological classification scheme and was discovered by the German-born British astronomer William Herschel on 21 May 1784. It is at a distance of 30,300 light years away from earth.<ref name="NASA/IPAC"></ref>


V Antliae

V Antliae (V Ant) is a Mira variable star in the constellation Antlia. It varies in brightness between magnitudes 8.2 and 14.0 with a period of 303 days.


Kappa Piscium

Kappa Piscium (κ Piscium) is a solitary, white-hued star in the zodiac constellation of Pisces. It is visible to the naked eye with an apparent visual magnitude of 4.94, forming the southeastern corner of the "Circlet" asterism in Pisces. Based upon a measured annual parallax shift of 21.25 mas as seen from Earth, it is located about 153 light years distant from the Sun. Appearing as a single point in the sky, it is easily split when viewed with a pair of binoculars, and displays three components. Kappa Piscium has an apparent magnitude of 4.87 at maximum brightness and 4.95 at minimum brightness, while the visual companions have apparent magnitudes of 9.96 and 11.20.
This is an A-type main-sequence star with a stellar classification of . The suffix designation indicates it is a "chemically peculiar" Ap star that displays abnormal abundances of silicon, strontium, and chromium. It is an Alpha2 Canum Venaticorum variable with a weak active magnetic field that causes it to fluctuate by 0.01 to 0.1 in magnitude as it rotates. It shows many lines of uranium, and possibly the rare element holmium in its spectrum. Its uranium and osmium content could have been provided by a nearby supernova. Compared to the Sun, it is deficient in oxygen relative to the magnesium abundance.
This star is a candidate member of the AB Doradus moving group, an association of stars with similar ages that share a common heading through space.
Naming.
In Chinese, (), meaning "Cloud and Rain", refers to an asterism consisting of refers to an asterism consisting of κ Piscium, 12 Piscium, 21 Piscium and λ Piscium. Consequently, the Chinese name for κ Piscium itself is (, .)


NGC 5544

NGC 5544 is a barred spiral galaxy in the constellation Boötes. It is interacting with spiral galaxy NGC 5545.


NGC 254

NGC 254 is a lenticular galaxy located in the constellation Sculptor. It was discovered by John Herschel in 1834.


Alicante 7

Alicante 7, also known as RSGC5, is an open cluster rich in red supergiants found in the Scutum-Crux Arm of the Milky Way Galaxy, along with RSGC1, Stephenson 2, RSGC3, Alicante 8, and Alicante 10. Alicante 7 contains 7 red supergiants, making it one of the most massive open clusters known.


HR 7484

HR 7484 (V1143 Cyg) is a binary star system in the northern constellation of Cygnus. It is dimly visible to the naked eye under good viewing conditions, having an apparent visual magnitude of 5.89. Based upon an annual parallax shift of 24.71, it is located 132 light years away. The system is moving closer with a heliocentric radial velocity of −14 km/s.
Observational history.
Radial velocity measurements taken at the Dominion Astrophysical Observatory in Victoria, British Columbia Canada in 1919 led to the determination by William Edmund Harper that HR 7484 is a double-lined spectroscopic binary. The next year he published an orbit with a period of 7.6383 days as compared to the modern value of 7.64075217 days.
Physical characteristics.
HR 7484 is a detached eclipsing binary, which means the orbital plane is aligned close to the line-of-sight from the Earth, causing the components to eclipse twice per orbit. The system is undergoing apsidal motion, with a rate greater than that predicted by general relativity. Both components are ordinary F-type main-sequence stars with similar physical properties. The star normally has an apparent magnitude of 5.89, but every 7.64 days (7 days, 15 hours, and 22 minutes) its brightness decreases to magnitude 6.37, approximately two thirds as bright. Five days and 17 hours after each primary eclipse, there is a secondary eclipse when the brightness drops to magnitude 6.06, about 85% of the normal brightness. Each eclipse lasts for 220 minutes. Both eclipses are partial.


60 Sagittarii

60 Sagittarii is a suspected binary star system in the southern constellation of Sagittarius. It has the Bayer designation A Sagittarii, while "60 Sagittarii" is the Flamsteed designation. This naked eye object forms the northwest corner of the asterism called the Terebellum and, with an apparent magnitude of approximately 4.84, it is the dimmest of the four stars in the Terebellum. It is located 379 light years from the Sun, based on parallax, but is moving closer with a radial velocity of −51 km/s.
The visible component is an aging G-type giant star with a stellar classification of G6 III, having exhausted the supply of hydrogen at its core and expanded to 17 the Sun's radius. In the "Bright Star Catalogue" it was listed with a class of , suggesting it is a mild barium star and thus might have a white dwarf companion. It is a red clump giant, indicating it is on the horizontal branch and is generating energy through the fusion of helium at its core. The star is radiating 170 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,997 K.


NGC 6356

NGC 6356 is a globular cluster located in the constellation Ophiuchus. It is designated as a II in the Shapley–Sawyer Concentration Class and was discovered by the German-born British astronomer William Herschel on 18 June 1784. The star cluster is more dense and bright towards the middle. NGC 6356 is located 80' north east of the brighter NGC 6333. It is at a distance of 49,600 light years away from earth.<ref name="NASA/IPAC"></ref>
The cluster is relatively metal-rich and therefore has a large amount of interstellar dust in its core.


NGC 7585

NGC 7585 is a lenticular galaxy with a peculiar shape resulting from an interaction between two galaxies. It is located 145 million light years away in the constellation Aquarius which, given its apparent dimensions, means that NGC 7585 is about 100,000 light years across. It was discovered by William Herschel on September 20, 1784.
Characteristics.
NGC 7585 is a lenticular galaxy with shells. The disk of the galaxy is also present and distinct from the shells. The shells are irregular and have radial and loop form, and one of them looks like a faint outer arm. The shells are probably the result of a merger that took place over a billion years ago. The shells are bluer than the rest of the galaxy and suggestive of a spiral galaxy taking part in a merger, while other features seem to be part of the accreted galaxy. The upper limit of the molecular gas mass based on CO imaging is 107.5 .
Nearby galaxies.
Two galaxies appear near NGC 7585. NGC 7576 is located 10.7 arcminutes southwest of NGC 7585, while NGC 7592 is located 15.2 arcminutes to the northeast. NGC 7576 is at a similar redshift with NGC 7585, but its normal shape indicates it hasn't interacted recently with NGC 7585. On the other hand, NGC 7592 appears disturbed, however it has double the redshift.


30 Arietis

30 Arietis (abbreviated 30 Ari) is a 6th-apparent-magnitude multiple star system in the constellation of Aries. "30 Arietis" is the Flamsteed designation. 30 Arietis A and B are separated by or about at a distance of 130 light years away. The main components of both systems are both binaries with a composite spectra belonging to F-type main-sequence stars, meaning they are fusing hydrogen in their cores. The 30 Arietis system is 910 million years old, one fifth the age of the Sun.
Star system.
30 Arietis A and B are separated by 38.1", corresponding to 1,500 AU at a distance of 130 light years. The pair are at almost the same distance, have very similar proper motions, and are considered almost certain to be gravitationally bound with a likely period around 34,000 years. The main components of both systems are both binaries with a composite spectra belonging to F-type main-sequence stars, meaning they are fusing hydrogen in their cores.
30 Arietis A is a spectroscopic binary with an orbital period of 1.1 days. The primary Aa is an F-type main sequence star about 31% more massive than the Sun, while the companion Ab is a faint red dwarf only about 15% the mass of the Sun.
30 Arietis B has been reported to have a red dwarf companion at a distance of and a likely giant exoplanet Bb at about . In 2020, after the inclination of the planetary orbit was measured, the "planet" was found to fall in the mass range of a brown or red dwarf. The more distant companion was referred to as C to distinguish it from Bb, and at about 0.5" it has been imaged using adaptive optics.


P Puppis

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


NGC 2357

NGC 2357 is a spiral galaxy located in the constellation of Gemini. It was discovered by Édouard Stephan on 6 February 1885.
Supernovae.
SN 2010bj, a Type II-P supernova, was detected in February 2010, and SN 2015I, a Type Ia supernova was detected in May 2015.


38 Virginis

38 Virginis is an F-type main sequence star in the constellation of Virgo. It is around 108 light years distant from the Earth.
Nomenclature.
The name 38 Virginis derives from the star being the 38th star in order of right ascension catalogued in the constellation Virgo by Flamsteed in his star catalogue. The designation "b" of 38 Virginis b derives from the order of discovery and is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet. In the case of 38 Virginis, only one was discovered, which was designated "b".
Stellar characteristics.
38 Virginis is an F-type main sequence star that is approximately 118% the mass of and 145% the radius of the Sun. It has a temperature of 6557 K and is about 1.9 billion years old. In comparison, the Sun is about 4.6 billion years old and has a temperature of 5778 K.
The star is metal-rich, with a metallicity ([Fe/H]) of 0.07 dex, or 117% the solar amount. Its luminosity () is 3.48 times that of the Sun.
A companion star is cataloged in the CCDM at a separation of half an arcsecond.
Planetary system.
The star is known to host one exoplanet, 38 Virginis b, discovered in 2016. This planet has a relatively low eccentricity out of any long-period giant exoplanet discovered, with an eccentricity of 0.03. The planet has a mass of around 4.5 times that of the planet Jupiter. Its orbit very likely puts it and any moons it may have in the habitable zone of its star.


NGC 332

NGC 332 is a compact and/or lenticular galaxy in the constellation Pisces. It was discovered on October 22, 1886 by Lewis Swift. It was described by Dreyer as "very faint, small, round, several stars near to south."


NGC 939

NGC 939 is a lenticular or elliptical galaxy in the constellation Eridanus. It is estimated to be 241 million light-years from the Milky Way and has a diameter of approximately 80,000 ly. NGC 939 was discovered on October 18, 1835 by astronomer John Herschel.
NGC 939 is better seen from the southern hemisphere because of its location south of the celestial equator.


AW Canum Venaticorum

AW Canum Venaticorum is a variable star in the constellation Canes Venatici. It is visible to the naked eye with a nominal apparent visual magnitude of 4.76. The distance to this star, as measured from its annual parallax shift of , is around 620 light years. It is moving closer with a heliocentric radial velocity of −44 km/s.
At the age of 1.1 billion years, this is an evolved red giant star with a stellar classification of M3- IIIa. It is a slow irregular variable of type Lb, with a brightness that ranges between magnitudes 4.73 and 4.85. The star has 2.2 times the mass of the Sun and has expanded to 117 times the Sun's radius. It is radiating 2,387 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,529 K.


Iota2 Cygni

Iota2 Cygni, Latinized from ι2 Cygni and often simply called ι Cygni, is a single star in the constellation Cygnus. It is visible to the naked eye as a white-hued point of light with an apparent visual magnitude of 3.76. Located around distant from the Sun based on parallax, it is drifting closer with a radial velocity of −19.5 km/s and is expected to come to within in around 783,000 years.
This it is an A-type main-sequence star with a stellar classification of A5V, a star that is currently fusing its core hydrogen. It is around 577 million years old and is spinning rapidly with a projected rotational velocity of 240 km/s. The star has 1.8 times the mass of the Sun and 3.8 times the Sun's radius. It is radiating 35 times the luminosity of the Sun from its photosphere at an effective temperature of 8,216 K. Based on rapid changes in the strength of a singly-ionized calcium absorption line, the star is likely host to a circumstellar disk.


NGC 2423-3

NGC 2423-3 is a red giant star approximately 2498 light-years away in the constellation of Puppis. The star is part of the NGC 2423 open cluster (hence the name "NGC 2423-3"). The star has an apparent magnitude of nine and an absolute magnitude of zero, with a mass of 2.4 times the Sun. As of 2007, it has been confirmed that an extrasolar planet orbits the star.
Planetary system.
NGC 2423-3 b is an exoplanet 10.6 times more massive than Jupiter, even more massive than Pi Mensae b, which has mass about 10.3 times Jupiter. Only the minimum mass is known since the orbital inclination is not known, so it is likely to be a brown dwarf instead, like NGC 4349-127 b. The planet orbits at 10.2 μpc, taking 1.956 years to orbit eccentrically around the star. Its eccentricity is about the same as Mercury, but less than Pluto. The planet has semi-amplitude of 71.5 m/s since if 10.6 planet orbits at 2.1 AU from 2.4 MS star.
This planet was discovered by Chad Lovis and Michel Mayor in July 2007. Lovis had also found three Neptune-mass planets orbiting HD 69830 in May 2006, also in Puppis.


Beta Horologii

Beta Horologii, Latinized from β Horologii, is the third-brightest star in the southern constellation of Horologium. It is faintly visible to the naked eye with an apparent visual magnitude of 4.98. Based upon an annual parallax shift of 11.07 mas as seen from Earth, it is located about 295 light years from the Sun. The star is moving away with a radial velocity of +24 km/s.
This is a solitary, A-type giant with a stellar classification of A3/5 III(m). It is a suspected chemically peculiar star of the metallic-line type. Beta Horologii has a relatively high rate of spin with a projected rotational velocity of 115 km/s, giving it an oblate shape with an equatorial bulge that is an estimated 10% wider compared to the polar radius. It has about 1.40 times the radius of the Sun and is radiating 63 times the Sun's luminosity from its photosphere at an effective temperature of 8,303 K.


Eta Crateris

Eta Crateris, Latinized from η Crateris, is a solitary star in the southern constellation of Crater. It marks the lip of the tilted bowl on the left side in the constellation. Eta Crateris lies in the sky NE of Zeta Crateris and NNW of 31 Crateris, the three stars forming an almost perfect right triangle with Eta at the right angle and 31 and Zeta the ends of the hypotenuse. Eta Crateris also lies to the right (west) of the bright star Gamma Corvi.
This star is faintly visible to the naked eye with an apparent visual magnitude of 5.17. With an annual parallax shift of 12.97 mas as seen from Earth, it is located around 280 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.08 due to interstellar dust. The star is receding from the Sun with a radial velocity of +15 km/s.
Eta Crateris is an ordinary A-type main sequence star with a stellar classification of A0 V. It is about 2.7 times the radius of the Sun and radiates 48.5 times the solar luminosity from its outer atmosphere at an effective temperature of 9,687 K. It 350 million years old and is spinning with a projected rotational velocity of 65 km/s.


47 Ophiuchi

47 Ophiuchi (47 Oph) is a binary star in the constellation Serpens. The combined apparent magnitude of the system is 4.54. The system is located about 98.1 light-years, or 30.1 parsecs away, based on its parallax as measured by Hipparcos.
47 Ophiuchi is a spectroscopic binary: that is, the two stars move fast enough that periodic Doppler shifts in the stars' spectra can be detected. In this case, the two stars have also been resolved using interferometry. The primary star is an F-type main-sequence star, that is 1.5 times the mass of the Sun and around twice as wide. Its companion star is 1.34 times the mass of the Sun, and 1.36 times the radius of the Sun. The two stars orbit each other every 26.3 days, and its orbital eccentricity is 0.481.
The designation 47 Ophiuchi was originally used for the star HR 6496. However, when constellation borders were redrawn, the star fell into the constellation Serpens, and the designation became used for this star, HR 6493, instead.


HD 74272

HD 74272 is a star in the constellation Vela. It has the Bayer designation n Velorum, while "HD 74272" is the identifier from the "Henry Draper catalogue". This is a white hued star that is faintly visible to the naked eye with an apparent visual magnitude of 4.74. It is located at a distance of approximately 1,800 light years from the Sun based on parallax. The star is drifting further away with a radial velocity of +17 km/s.
This is an aging, massive bright giant star with a stellar classification of A5 II. It is an estimated 30 million years old with 8.8 times the mass of the Sun. Having exhausted the supply of hydrogen at its core, it has expanded to around 33 times the radius of the Sun. The star is radiating 3,287 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 7,595 K.


Pi Hydrae

Pi Hydrae (π Hya, π Hydrae) is a star in the constellation Hydra with an apparent visual magnitude of 3.3, making it visible to the naked eye. Parallax measurements put this star at a distance of about from the Earth.
The spectrum of this star shows it to have a stellar classification of K1 III-IV, with the luminosity class of 'III-IV' suggesting it is in an evolutionary transition stage somewhere between a subgiant and a giant star. It has a low projected rotational velocity of 2.25 km s−1. Pi Hydrae is radiating energy from its outer envelope with an effective temperature of 4,670 K, giving it the orange hue of a K-type star.
Pi Hydrae is a type of giant known as a cyanogen-weak star, which means that its spectrum displays weak absorption lines of CN− relative to the metallicity. (The last is a term astronomers use when describing the abundance of elements other than hydrogen and helium.) Otherwise, it appears to be a normal star of its evolutionary class, having undergone first dredge-up of nuclear fusion by-products onto its surface layers. The measured angular diameter of this star, after correction for limb darkening, is . At its estimated distance, this yields a physical size of about 12–13 times the radius of the Sun. It has an estimated mass of 2.45 times the mass of the Sun.
References.
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NGC 7080

NGC 7080 is a barred spiral galaxy located about 204.5 million light-years away in the constellation of Vulpecula. It has an estimated diameter of about 100,000 light-years which would make it similar in size to the Milky Way. NGC 7080 was discovered by astronomer Albert Marth on September 6, 1863.
According to Harold Corwin, NGC 7054 is a duplicate observation of NGC 7080.
On December 5, 1998 a supernova of type Ic-pec was discovered in NGC 7080.


D Centauri

D Centauri is a double star in the southern constellation of Centaurus. The system is faintly visible to the naked eye as a point of light with a combined apparent magnitude of +5.31; the two components are of magnitude 5.78 and 6.98, respectively. It is located at a distance of approximately 610 light years from the Sun based on parallax, and is drifting further away with a radial velocity of ~10 km/s.
The dual nature of this star was announced by C. Rumker in 1837. As of 2015, the pair had an angular separation of along a position angle of 242°. This orange-hued double has a combined stellar classification of K3III, matching an aging giant star that has exhausted the supply of hydrogen at its core. In 1984, C. J. Corbally found a class of K4IIIab for the primary and K2IIIb for the fainter secondary.


45 Eridani

45 Eridani is a single star located around 700 light years away from the Sun in the equatorial constellation of Eridanus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.91. This body is moving away from the Earth with a heliocentric radial velocity of +15 km/s.
The stellar classification for this star is K0/1 III, which indicates this is an aging K-type giant star that has exhausted the hydrogen supply at its core and expanded. It has reached 50 times the Sun's radius and is radiating 788 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,322 K.


Beta Piscis Austrini

Beta Piscis Austrini (β Piscis Austrini) is catalogued as a binary star system in the southern constellation of Piscis Austrinus. It is visible to the naked eye with an apparent visual magnitude of +4.29. Based upon an annual parallax shift of 22.84 mas as seen from the Earth, the star is located 143 light years from the Sun. These coordinates are a source of X-ray emission with a luminosity of , which is most likely coming from a source other than the A-type stars.
Oblak (1978) identified this as a triple star system, although subsequent sources list it as a binary. The magnitude 4.29 primary, component A, is a white-hued A-type main sequence star with a stellar classification of A1 V. It has an estimated 2.3 times the mass of the Sun and 2.1 times the Sun's radius. The star is radiating 37 times the solar luminosity from its photosphere at an effective temperature of 9,638 K. There is evidence for an infrared excess, indicating the presence of an orbiting debris disk. This has an estimated temperature of 188 K, indicating an orbital distance of 12 AU from the host star. The magnitude 7.8 secondary, component B, has a class of A2 V and lies at an angular separation of 30.3 arc seconds.
Beta Piscis Austrini is moving through the Galaxy at a speed of 14.4 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,900 and 28,300 light years from the center of the Galaxy.
With Delta and Zeta it constituted Tien Kang ("heavenly rope") in China.


Abell 7

Abell 7 is a faint planetary nebula located 1800 light-years away in the constellation of Lepus. It has a generally spherical shape about 8 light-years in diameter. Within the sphere are complex details that are brought out by narrowband filters. Abell 7 is estimated to be only 20,000 years old, but the central star, a fading white dwarf, is estimated to be some 10 billion years old.


NGC 3664

NGC 3664 is a magellanic barred spiral galaxy in the constellation of Leo. It is located about 80 million light years away from Earth, which means, given its apparent dimensions, that NGC 3664 is approximately 50,000 light years across. It was discovered by Wilhelm Tempel on March 14, 1879. The galaxy is characterised by its asymmetric shape, which features a single spiral arm and an off-centre bar. The distribution of HI is equally asymmetric.
Nearby galaxies.
NGC 3664 has a smaller satellite galaxy, known as NGC 3664A or UGC 6418, which lies 6.2 arcminutes to the south, at a projected distance of 25 to 30 kiloparsecs from NGC 3664. The HI mass of NGC 3664A is , which means that the system has similar masses as the system of the Large and Small Magellanic Cloud. A HI bridge has been detected to connect the two galaxies in images obtained by the Very Large Array. The HI also appears warped at the side of NGC 3664 opposite of NGC 3664A, indicating an ongoing interaction. The bar of NGC 3664 could have developed due to this interaction.
NGC 3664 and its satellite belong to the NGC 3640 group, named after the galaxy NGC 3640. Other members of the galaxy group include NGC 3630, NGC 3641, and NGC 3643. The group belongs to the Leo II groups, a large collection of galaxies belonging to the Virgo supercluster scattered across 30 million light years of space west of the Virgo cluster.


KELT-3b

KELT-3b is an extrasolar planet orbiting the F-type main-sequence star KELT-3 690 light years in the zodiac constellation Leo. It was discovered in 2013 by KELT's telescope in Arizona.
Properties.
This planet has 44% more mass than Jupiter, but has expanded to 1.34 times the radius of the latter. It has a temperature of 1,811 K, which gives it a Hot Jupiter class. KELT-3b has a lower density than Jupiter, and completes a revolution in less in 3 days. This corresponds with a orbital distance of 0.04 AU, which is 10 times closer than Mercury (planet) orbits the Sun.
The planetary equilibrium temperature is 1829 K, but measured temperature is hotter at 2132 K. The radiation of the moderately active host star KELT-3 do not produce a detectable ionization and consequent Lyman-alpha line emisssion in the atmosphere of the KELT-3b.
Discovery.
KELT-3b was discovered in 2013. The light curves and parameters of both the planet and the star were observed. The paper also states that there is uncertainty about the system age.


NGC 630

NGC 630 is an elliptical galaxy in the constellation Sculptor. It is estimated to be 275 million light years from the Milky Way and has a diameter of approximately 125,000 light years. The object was discovered on October 23, 1835 by the English astronomer John Herschel.


RZ Normae

RZ Normae is an R Coronae Borealis type variable star in the constellation Norma. It has a baseline magnitude of 10.2, dropping down to dimmer than 16.2 at its minima. It was discovered by the astronomer Sergei Gaposchkin in 1952.
It has around 60% the mass of the Sun and an effective (surface) temperature of around 6750 K.


XO-2Nb

XO-2Nb (or rarely XO-2Bb) is an extrasolar planet orbiting the star XO-2N, the fainter component of XO-2 wide binary star in the constellation Lynx. This planet was found by the transit method in 2007 by Burke et al. This was the second such planet found by the XO telescope.
Like most planets found by the transit method, it is a roughly Jupiter sized planet that orbits very close to its host star; in this case, it has a surface temperature of about 1200 K, so it belongs to a group of exoplanets known as hot Jupiters. The planet takes 2.6 days to orbit the star at the average distance of 0.0369 AU. The planet has mass of 57% of Jupiter and radius of 97% of Jupiter. The radius is relatively large for its mass, probably due to its intense heating from its nearby star that bloats the planet's atmosphere. The large radius for its mass gives a low density of 820 kg/m3.


List of stars in Cetus

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


List of stars in Ara

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


43 Sagittarii

43 Sagittarii is a single star in the southern constellation of Sagittarius. It has the Bayer designation d Sagittarii, while "43 Sagittarii" is the Flamsteed designation. This object is visible to the naked eye as a faint, yellow-hued star with an apparent visual magnitude of 4.88. From parallax measurements, it is estimated to lie around 470 light years away from the Sun. The star is drifting further from the Earth with a heliocentric radial velocity of +15.2 km/s. It is located near the ecliptic and thus is subject to lunar occultations.
This is an aging giant/bright giant star with a stellar classification of G8II-III, and is most likely (97% chance) on the horizontal branch. It is around 350 million years old with 3.3 times the mass of the Sun. Having exhausted the supply of hydrogen at its core, the star has expanded to 24 times the Sun's radius and is now generating energy through core helium fusion. It is radiating 277 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,813 K.


Pi Eridani

Pi Eridani, Latinized from π Eridani, is a star in the constellation Eridanus. It has an apparent visual magnitude of 4.40, which is bright enough to be seen on a dark, clear night. Based upon parallax measurements, it is located roughly 480 light years from the Sun.
This is an evolved red giant star with a stellar classification of M1 III, and is currently on the asymptotic giant branch. It is a slow irregular variable type LB that can increase in magnitude up to 4.38. The measured angular diameter of this star is . At the estimated distance of Pi Eridani, this yields a physical size of about 77 times the radius of the Sun. It shines with 1,123 times the luminosity of the Sun from an outer atmosphere at an effective temperature of 3,841 K.
References.
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NGC 2204

NGC 2204 is an open cluster in the Canis Major constellation. It was discovered by William Herschel on 6 February 1785.


Egg Nebula

The Egg Nebula (also known as RAFGL 2688 and CRL 2688) is a bipolar protoplanetary nebula approximately 3,000 light-years away from Earth. Its peculiar properties were first described in 1975 using data from the 11 µm survey obtained with sounding rocket by Air Force Geophysical Laboratory (AFGL) in 1971 to 1974. (Previously, the object was catalogued by Fritz Zwicky as a pair of galaxies.)
The Egg Nebula's defining feature is the series of bright arcs and circles surrounding the central star. A dense layer of gas and dusts enshrouds the central star, blocking its direct light from our view. However, the light from the central star penetrates the thinner regions of this dusty enclosure, illuminating the outer layers of gas to create the arcs seen in this resplendent image (Hubble Site). Spectra of the starlight scattered by the dust reveal that the central star has a spectral type of F5. The photosphere of an F5 star is about 900 K hotter than that of the Sun, but it is still not hot enough to have begun ionizing the nebula. Therefore the Egg Nebula is at a slightly earlier evolutionary stage than the Westbrook Nebula whose spectral type B0 central star has just recently begun to ionize the nebula.
The dusty enclosure around the central star is very likely a disc. The bipolar outflows in the image indicate that the system has angular momentum, which is very likely generated by an accretion disc. In addition, a disc geometry would account for the varying thickness of the enclosure that allows light to escape along the disc's axis and illuminate the outer layers of gas, but still blocks it from our direct view along the disc edge. Although dusty discs have been confirmed around several post-AGB objects (S. De Ruyter et al., 2006), a disc around the Egg Nebula is yet to be confirmed.
The Egg Nebula shows strong microwave emission from rotational transitions of carbon monoxide (CO) and hydrogen cyanide (HCN). The presence of strong HCN emisssion indicates that the progenitor AGB star was a carbon star. The CO and HCN spectra have a strong blue-shifted P Cygni absorption feature, and show the presence of a ~100 km/sec high velocity wind inside of the remnant AGB wind (which is expanding at 18 km/sec).
The Egg Nebula was photographed by the Wide Field and Planetary Camera 2 of the NASA/ESA Hubble Space Telescope.
The Egg Nebula emits polarized light which can also be detected visually by a medium-sized telescope.


Gamma Pyxidis

Gamma Pyxidis, Latinized from γ Pyxidis, is a single, orange-hued star in the southern constellation Pyxis. It is visible to the naked eye, having an apparent visual magnitude of 4.010. Based upon an annual parallax shift of 15.73 mas as seen from Earth, it is located about 207 light years from the Sun. The star is moving further from the Sun with a radial velocity of +24.5 km/s.
Properties.
This is an evolved K-type giant star with a stellar classification of K3 III. It is a red clump star on the horizontal branch, indicating that it is generating energy through helium fusion at its core. The composition of the stellar atmosphere is similar to the Sun, having roughly the same abundance of iron in its spectrum. The star has an estimated 1.64 times the mass of the Sun and has expanded to nearly 22 times the Sun's radius. At the age of around four billion years, it is radiating 178 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,270 K.
Gamma Pyxidis is moving through the Galaxy at a speed of 54.2 km/s relative to the Sun. Its projected Galactic orbit carries it between 21,300 and 30,700 light years from the center of the Galaxy.
Naming.
In Chinese, (), meaning "Celestial Dog", refers to an asterism consisting of γ Pyxidis, e Velorum, f Velorum, β Pyxidis, α Pyxidis and δ Pyxidis. Consequently, γ Pyxidis itself is known as (, .)


NGC 2080

NGC 2080 (The "Ghost Head Nebula") is a star-forming region and emission nebula to the south of the 30 Doradus (Tarantula) nebula, in the southern constellation Dorado. It belongs to the Large Magellanic Cloud, a satellite galaxy to the Milky Way, which is at a distance of 168,000 light years. NGC 2080 was discovered by John Frederick William Herschel in 1834. The Ghost Head Nebula has a diameter of 50 light-years and is named for the two distinct white patches it possesses, called the "eyes of the ghost". The western patch, called A1, has a bubble in the center which was created by the young, massive star it contains. The eastern patch, called A2, has several young stars in a newly formed cluster, but they are still obscured by their originating dust cloud. Because neither dust cloud has dissipated due to the stellar radiation, astronomers have deduced that both sets of stars formed within the past 10,000 years. These stars together have begun to create a bubble in the nebula with their outpourings of material, called stellar wind.
The presence of stars also greatly influences the color of the nebula. The western portion of the nebula has a dominant oxygen emission line because of a powerful star on the nebula's outskirts; this colors it green. The rest of the nebula's outskirts have a red hue due to the ionization of hydrogen. Because both hydrogen and oxygen are ionized in the central region, which appears pale yellow; when hydrogen is energized enough to emit a second wavelength of light, it appears blue, as in the area surrounding A1 and A2.
NGC 2080 should not be confused with the Ghost Nebula (Sh2-136) or the Little Ghost Nebula (NGC 6369).


Pi Cephei

Pi Cephei (π Cephei) is a trinary star located in the constellation Cepheus. With a combined apparent magnitude of about 4.4, the system is faintly visible to the naked eye. The inner pair of stars orbits in 1.5 years while the outer companion completes one orbit in about 160 years.
Pi Cephei was found to have a visual companion star by Otto Wilhelm von Struve in 1843. That the primary is itself a spectroscopic binary was first noticed by William Wallace Campbell in 1901 using photographic plates taken at Lick Observatory.


NGC 385

NGC 385 is an unbarred lenticular galaxy located in the constellation Pisces. It was discovered on November 4, 1850 by Bindon Stoney. It was described by Dreyer as "pretty faint, pretty small, round, northeastern of 2.", the other being NGC 384. Along with galaxies NGC 375, NGC 379, NGC 382, NGC 383, NGC 384, NGC 386, NGC 387 and NGC 388, NGC 385 forms a galaxy cluster called Arp 331.


Arp 302

Arp 302 (also known as Exclamation Point Galaxy) is a galaxy in the constellation Boötes. Arp 302, also known as VV 340 or UGC 9618 consists of a pair of very gas-rich spiral galaxies in their early stages of interaction. An enormous amount of infrared light is radiated by the gas from massive stars that are forming at a rate similar to the most vigorous giant star-forming regions in our own Milky Way. Arp 302 is 450 million light-years away from Earth, and is the 302nd galaxy in Arp's Atlas of Peculiar Galaxies.


HD 9578

HD 9578 is a candidate wide binary star system located at a distance of approximately 183 light-years from the Sun in the southern constellation of Sculptor. The main star must be viewed with binoculars or a telescope, as its low apparent visual magnitude of 8.35 is too faint to be viewed with the naked eye. The system is drifting closer to the Sun with a radial velocity of −4 km/s.
The primary component is an ordinary G-type main-sequence star with a stellar classification of G1V. It is around five and a half billion years old, and is spinning with a projected rotational velocity of 2.4 km/s. The star has nearly the same mass as the Sun but with an 11% greater girth. It is radiating 1.4 times the luminosity of the Sun from its photosphere at an effective temperature of 5,798 K.
A faint co-moving companion was detected in 2015, located at an angular separation of along a position angle of from the primary, corresponding to a projected separation of . Designated component B, it is a red dwarf with a class of around M4 and has an estimated 0.21 times the mass of the Sun.
The discovery of a candidate extrasolar planetary companion was announced in a press release in October 2009. Designated HD 9578 b, this object has at least 0.62 times the mass of Jupiter. It takes to orbit the primary, with an orbital semimajor axis of 1.27 AU.


HK Aquarii

HK Aquarii is a single variable star in the equatorial constellation of Aquarius. It is invisible to the naked eye, having an average apparent visual magnitude that fluctuates around 10.99. The star is located at a distance of 81 light years from the Sun based on parallax. The radial velocity is poorly constrained but it appears to be drifting further away at a rate of ~2 km/s.
This is a small red dwarf star; an M-type main-sequence star with a stellar classification of M0Ve, where the 'e' indicates emission lines in the spectrum. It has 57% of the mass of the Sun and has 53% of the Sun's girth. The star is spinning with a projected rotational velocity of 69 km/s and has a rotation period of just . Based on the abundance of iron in the atmosphere, it has a high metallicity; what astronomers term the abundances of elements with a higher atomic number than helium. The star is radiating around 5% of the luminosity of the Sun from its photosphere at an effective temperature of 3,800 K.
HK Aquarii is classified as a BY Draconis variable and has been observed ranging in brightness from visual magnitude 10.72 down to 10.94. This star is noteworthy for being unusually active for an isolated red dwarf; it rotates rapidly, generating a strong magnetic field that creates large starspots and powerful flares. Star spots have been reported at a variety of latitudes, but not at the poles. Flaring activity was reported in 1987, and a steady X-ray emission has been detected. These are characteristic of very young stars; although it is not close to any youthful open cluster, it is a possible ejected member of the Pleiades. (A 2016 study instead suggests it is a member of the Octans association.)
The signature of prominences has been detected in the star's atmosphere. These display evidence of periodic oscillations and can reach altitudes greater than two-third's of the star's radius. The prominences can obtain a higher mass and volume compared to similar features on the Sun.


62 Arietis

62 Arietis is a single star in the northern constellation of Aries, a few degrees to the north of Tau Arietis. "62 Arietis" is the Flamsteed designation. It is visible to the naked eye as a dim, yellow-hued star with an apparent visual magnitude of 5.52. Based upon an annual parallax shift of , it is approximately distant from the Earth.
This object is an aging giant star with a stellar classification of G5 III, most likely (96% chance) on the horizontal branch. Having exhausted the supply of hydrogen at its core, the star has expanded to 35 times the Sun's radius. It is around 219 million years old with 3.7 times the mass of the Sun. The star is radiating 533 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,665 K.
Chinese name.
In Chinese astronomy, 62 Arietis is called 天阿, Pinyin: Tiānhé, meaning "Celestial River", because this star is marking itself and stand alone in "Celestial River" asterism, Hairy Head mansion (see : Chinese constellation). 天阿 (Tiānhé) is westernized into "Teen Ho", but according to another opinion about this asterism, "Teen Ho" is asterism consisting four stars in Aries.
Another "Tiānhé" ("Celestial River") in Tail mansion, is asterism consisting the stars in Ophiuchus


Zeta Aurigae

Zeta Aurigae (ζ Aurigae, abbreviated Zeta Aur, ζ Aur), traditionally known as Sadatoni (among other names), is a binary star in the northern constellation of Auriga. Based upon parallax measurements made during the Hipparcos mission, this system is approximately distant from the sun. It has a combined apparent visual magnitude of 3.75, which is bright enough to be seen with the naked eye.
The two components are designated Zeta Aurigae A (officially named Saclateni , an old misspelling of "Sadatoni") and B.
Nomenclature.
"ζ Aurigae" (Latinised to "Zeta Aurigae") is the system's Bayer designation. The designations of the two components as "ζ Aurigae 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).
The system bore the traditional names "Haedus I" (also "Hoedus") and "Sadatoni" (rarely "Saclateni"). It was one of the two "haedi" (Latin: 'kids') of the she-goat Capella, the other being Haedus II, Eta Aurigae. The name Sadatoni is from the Arabic الساعد الثاني "as-sācid aθ-θānī" "the second arm (of the charioteer)". The rare traditional name "Azaleh" is shared (in the form "Hassaleh") with Iota Aurigae. 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 names "Saclateni" for the component Zeta Aurigae A and "Haedus" for Eta Aurigae on 30 June 2017 and they are both now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Pillars", refers to an asterism consisting of Zeta Aurigae, Epsilon Aurigae, Eta Aurigae, Upsilon Aurigae, Nu Aurigae, Tau Aurigae, Chi Aurigae and 26 Aurigae. Consequently, the Chinese name for Zeta Aurigae itself is (, .)
Binary system.
Zeta Aurigae was first recognized as a spectroscopic binary by William Hammond Wright while analyzing photographic plates taken at Lick Observatory between 1898 and 1908. This star is among those earlier described by Antonia Maury as having a composite spectrum. The first orbit was determined in 1924 by William Edmund Harper using measurements taken at Dominion Observatory, his orbital elements are very similar to the most recent determinations. Harper also noticed that the composite nature of the spectrum had disappeared on the one plate when the K type primary was nearest the sun indicating a possible eclipse. In 1932 the eclipsing binary nature of the system was confirmed by Paul Guthnick, Heribert Schneller and independently Josef Hopmann.
Properties.
Zeta Aurigae is an eclipsing binary with the orbital plane being oriented close to the line of sight from the Earth; the inclination of this system is estimated as 87.0°. As a result, an eclipse of one star by the other occurs during each orbit, causing the magnitude to decrease to +3.99. The pair have an orbital period of 972 days (2.66 years) and an eccentricity of 0.4. The primary component, Zeta Aurigae A, has been categorized as a K-type bright giant or supergiant star. Its companion, Zeta Aurigae B, is a B-type main sequence star of stellar classification B5 V or B7 V.


Tau Leonis

Tau Leonis (τ Leo) is a star in the zodiac constellation of Leo. Because it is located near the ecliptic, it is subject to occultations by the Moon. It has an apparent visual magnitude of 5.00, which is bright enough to be seen with the naked eye. The distance to this star, as estimated using parallax measurements, is 560 light years. It is moving closer to the Sun with a radial velocity of −9 km/s.
This G-type giant star has a stellar classification of G8- IIIa and currently resides on the red giant branch. It has about 390% of the Sun's mass. The star is much younger than the Sun, with an age of around 190 million years. As an evolved giant, it has expanded to about 25 times the Sun's radius and radiates 330 times the luminosity of the Sun. The effective temperature of the outer atmosphere is 4,910 K.


Epsilon Pegasi

Epsilon Pegasi (Latinised from ε Pegasi, abbreviated Epsilon Peg, ε Peg), formally named Enif , is the brightest star in the northern constellation of Pegasus.
With an average apparent visual magnitude of 2.4, this is a second-magnitude star that is readily visible to the naked eye. The distance to this star can be estimated using parallax measurements from the Hipparcos astrometry satellite, yielding a value of around .
Nomenclature.
"ε Pegasi" (Latinised to "Epsilon Pegasi") is the star's Bayer designation.
It bore the traditional name "Enif" derived from the Arabic word for 'nose', due to its position as the muzzle of Pegasus. 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 "Enif" for this star.
Other traditional names for the star include "Fom al Feras", Latinised to "Os Equi". In Chinese, (), meaning "Rooftop (asterism)", refers to an asterism consisting of Epsilon Pegasi, Alpha Aquarii and Theta Pegasi. Consequently, the Chinese name for Epsilon Pegasi itself is (, .)
Physical characteristics.
Epsilon Pegasi is a red supergiant star, as indicated by the stellar classification of K2 Ib. It is estimated to be 12 times the Sun's mass. The measured angular diameter of this star, after correction for limb darkening, is . At the estimated distance of this star, this yields an enormous physical size of about 185 times the radius of the Sun. From this expanded envelope, it is radiating roughly 12,250 times the luminosity of the Sun at an effective temperature of 4,337 K. This temperature is cooler than the Sun, giving it the orange-hued glow of a K-type star.
Epsilon Pegasi has been observed to brighten radically upon a few occasions, giving rise to the theory that it (and possibly other supergiants) erupt in massive flares that dwarf those of the Sun. It is a type LC slow irregular variable star that varies from +0.7 to +3.5 in magnitude. The spectrum shows an overabundance of the elements strontium and barium, which may be the result of the s-process of nucleosynthesis in the outer atmosphere of the star. It has a relatively high peculiar velocity of .
Evolution.
Epsilon Pegasi has exhausted its core hydrogen and expanded away from the main sequence. It is almost certainly on the horizontal branch fusing helium in its core. It is sufficiently massive that it may die in a core-collapse supernova, or it may shed its outer layers and leave behind an unusual oxygen–neon white dwarf.
Pulfrich effect.
Epsilon Pegasi is a fine example to observe the Pulfrich effect. This optical phenomenon is described on page 1372 of "Burnham's Celestial Handbook". According to John Herschel: "The apparent pendulum-like oscillation of a small star in the same vertical as the large one, when the telescope is swung from side to side".
References.
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49 Orionis

49 Orionis is a single star in the equatorial constellation of Orion. It has the Bayer designation d Orionis, while "49 Orionis" is the Flamsteed designation. This object is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.80. It is located 141 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −5 km/s.
In the past 49 Orionis was reported as a spectroscopic binary and an orbit was computed with a period of 445.74 days and an eccentricity of 0.549. But it was later determined to be single.
This object is an A-type main-sequence star with a stellar classification of A4Vn, where the 'n' suffix indicates broadened "nebulous" lines caused by rapid rotation. It is around 284 million years old with a projected rotational velocity of 186 km/s. This spin is giving the star an oblate shape with an equatorial bulge that is an estimated 8% larger than the polar radius. The star has 1.8 times the mass of the Sun and double the Sun's radius. It is radiating 22 times the Sun's luminosity from its photosphere at an effective temperature of 8,416 K.


NGC 5533

NGC 5533 is an unbarred spiral galaxy in the constellation Boötes. It was discovered by the astronomer William Herschel on May 1, 1785. It has a regular structure, with one tightly wound spiral; its disk is inclined about 53 degrees towards the line of sight.
It is a member of the NGC 5557 Group, along with several other galaxies.


HD 30562

HD 30562 is a star in the equatorial constellation of Eridanus. It has a golden hue and can be viewed with the naked eye under good seeing conditions, having an apparent visual magnitude of 5.77. The distance to this star is 85 light years based on parallax. It is drifting further away with a high radial velocity of +77 km/s, having come to within some 236,000 years ago.
The stellar classification of HD 30562 has varied somewhat depending on the study, including types G2IV, G5V, and F8V. It is about 4.4 billion years old and appears to be chromospherically inactive. The star is spinning with a projected rotational velocity of 5.8 km/s, giving it a rotation period of 24.2 days. Based on the abundance of iron appearing in the sprectrum, the metallicity of this star, what astronomers term the abundance of elements with higher atomic numbers than helium, is about 70% higher than in the Sun. HD 30562 has 25% greater mass than the Sun and a 57% larger radius. The star is radiating almost three times the luminosity of the Sun from its photosphere at an effective temperature of 5,983 K.
In August 2009, it was found that this star has a Jupiter-like planet that orbits in a very eccentric path.


FL Lyrae

FL Lyrae is the variable star designation for an eclipsing binary star system in the northern constellation of Lyra. The combined apparent magnitude of the pair is 9.36, which means they are too faint to be seen with the naked eye. Parallax measurements from the Hipparcos spacecraft put the system at a distance of around 420 light years from the Sun. This star system was in the view field of the Kepler space telescope during 2009−2014, which allowed monitoring during that spacecraft's mission.
The variability of this system was discovered from photographic plates in 1935. It is a binary star system with an orbital plane that is nearly aligned with the line of sight to the Earth. Once every 2.1781542 day orbit, each of the closely orbiting stars eclipses its partner, causing a net magnitude drop to 9.4 during the primary eclipse and to magnitude 9.1 when the secondary component is eclipsed. The secondary member covers 51% of the larger star during the primary eclipse, while the primary covers 88% of the secondary.
The measureable properties of an eclipsing binary can allow the physical parameters of the individual components to be worked out in some detail. The primary component has 122% of the Sun's mass, spans 128% of the radius of the Sun, and is emitting 217% of the Sun's luminosity. It is most likely an F-type main sequence star with a stellar classification of F8. The secondary is smaller, with 96% of the mass of the Sun, 96% of the Sun's radius, and radiates just 65% of the Sun's luminosity. This is a G-type main sequence star of class G8.
Based upon light variations measured during eclipses by the Kepler spacecraft, the system may contain a third body with twice the mass of Jupiter and an orbital period of under seven years. As of 2015, this remains to be confirmed.


Kepler-84

Kepler-84 is a Sun-like star 4700 light years from the Sun. It is a G-type star. The stellar radius measurement has a large uncertainty of 48% as in 2017, complicating the modelling of the star. The Kepler-84 star has two suspected stellar companions. Four red dwarfs are few arcseconds away and at least one is probably gravitationally bound to Kepler-84. Another (which is a background star with a probability 0.5%) is an yellow star of mass 0.855 on projected separations of 0.18″ or 0.26″ (213.6 AU).
Planetary system.
Kepler-84 is orbited by five known planets, four small gas giants and a Super-Earth. Planets Kepler-84b and Kepler-84c were confirmed in 2012 while the rest was confirmed in 2014. To keep the known planetary system stable, no additional giant planets can be located within 7.4 AU from the parent stars.


HD 80606 and HD 80607

HD 80606 and HD 80607 are two stars comprising a binary star system. They are approximately 217 light-years away in the constellation of Ursa Major. Both stars orbit each other at an average distance of 1,200 astronomical units. The binary system is listed as Σ1341 in the Struve Catalogue of Double Stars, however this designation is not in wide use and the system is usually referred to by the HD designations of its constituent stars. An extrasolar planet has been confirmed to orbit HD 80606 in a highly elliptical orbit.
Planetary system.
The variable radial velocity of HD 80606 was first noticed in 1999 from observations with the 10-m Keck 1 telescope at the W. M. Keck Observatory in Hawaii by the G-Dwarf Planet Search, a survey of nearly 1000 nearby G dwarfs to identify extrasolar planet candidates. The star was then followed up by the Geneva Extrasolar Planet Search team using the ELODIE spectrograph mounted on the 1.93-m telescope at the Haute-Provence Observatory. The discovery of HD 80606 b was announced on April 4, 2001. Its orbit is misaligned with the star's rotation at 53 degrees. Additional studies using the Spitzer Space Telescope in the infrared, and the Very Large Array in the millimeter radio, have shown that the highly eccentric planet 'b' orbiting HD 80606 grazes the parent star at its closest passage to produce difficult-to-detect stellar lobing, severe 'space weather', aurorae and other non-thermal activity.
At the time, its orbit was the most eccentric orbit of any extrasolar planet known. It has an eccentricity of 0.9336, comparable to that of Comet Halley in the Solar System. The eccentricity may be a result of the Kozai mechanism, which would occur if the planet's orbit is significantly inclined to that of the binary stars. This conclusion is reinforced by the detection of the misalignment, an expected result of the Kozai mechanism.
In a simulation of a 10 million year span, the planet "sweeps clean" most test particles within 1.75 AU of HD 80606. The 8:1 resonance hollows out another Kirkwood gap at 1.9 AU. There cannot be any habitable planets in this system. Also, observation has ruled out planets heavier than 0.7 Jupiter mass with a period of one year or less.


Tau7 Eridani

Tau7 Eridani is a solitary star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 5.235. Using the parallax method, the distance to this star can be estimated as around 251 light years.
This is an A-type main sequence star with a stellar classification of A3 Vs, where the 's' indicates it has narrow absorption lines. It may be a chemically peculiar Am star, which means it displays unusual abundances of certain elements in its surface layers. Tau7 Eridani appears to be a low amplitude variable that displays slight fluctuations in luminosity over a period of 7.17 days. It is slowly rotating with a projected rotational velocity of 18 km/s, and is around 387 million years old.


NGC 208

NGC 208 is a spiral galaxy located approximately 229 million light-years from the Solar System in the constellation Pisces. It was discovered on October 5, 1863 by Albert Marth.


Turtle Beak

The Turtle Beak mansion (觜宿, pinyin: Zī Xiù) is one of the twenty-eight mansions of the Chinese constellations. It is one of the western mansions of the White Tiger.


Mu Mensae

μ Mensae, Latinized as Mu Mensae, is a solitary, blue-white hued star in the southern constellation of Mensa. With an apparent visual magnitude of 5.54, it is just bright enough to be faintly visible to the naked eye. Based upon an annual parallax shift of 6.8405 mas as seen from GAIA, this star is located roughly 477 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.09 due to interstellar dust.
The stellar classification of suggests that it is a B-type star with a spectrum that shows mixed traits of a giant and a bright giant star. It may be chemically peculiar with an overabundance of silicon in its outer atmosphere. The estimated radius of the star is 3.3 times that of the Sun. It is radiating 216 times the Sun's luminosity from its photosphere at an effective temperature of 12,550 K.


HD 220074

HD 220074 is a star located in the northern constellation of Cassiopeia, near the western border with Cepheus. It has a reddish hue and is dimly visible to the naked eye, having an apparent visual magnitude of +6.39. The star is located at a distance of approximately 1,070 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −37 km/s.
This star was assigned a stellar classification of K1V in the "Bright Star Catalogue" but is now known to be a red giant with a class of M2III, based on its radius and surface gravity. With the supply of hydrogen at its core exhausted, the star has expanded and cooled off the main sequence. It is around 4.5 billion years old with an estimated mass equal to ~1.2 times the mass of the Sun but 60 times the Sun's radius. The star is radiating 783 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,935 K.
Planetary system.
From September 2008 to June 2012, the team B.-C. Lee, I. Han, and M.-G. Park observed HD 220074 with "the high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO)".
In 2012, a long-period, wide-orbiting eccentric planet was deduced by radial velocity changes. This finding was published in November, gaining the designation HD 220074 b. Along with HD 208527 b this is one of the first two candidate planets found orbiting red giants.


Xi Mensae

ξ Mensae, Latinized as Xi Mensae, is a single star in the southern circumpolar constellation of Mensa. It has a yellow-orange hue and is just barely visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.84. This object is located about 366 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −5 km/s.
This object is an aging giant star with a stellar classification of G8/K0III. It is 281 million years old with 1.91 times the mass of the Sun. The star displays micro-variability, fluctuating in brightness by 0.0049 magnitudes with a period of 148 days. With the supply of hydrogen at its core exhausted, the star has cooled and expanded to nine times the Sun's radius. It is radiating 50 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 5,131 K.


NGC 3783

NGC 3783 is a barred spiral galaxy located about 135 million light years away in the constellation Centaurus. It is inclined by an angle of 23° to the line of sight from the Earth along a position angle of about 163°. The morphological classification of SBa indicates a bar structure across the center (B) and tightly-wound spiral arms (a). Although not shown by this classification, observers note the galaxy has a luminous inner ring surrounding the bar structure. The bright compact nucleus is active and categorized as a Seyfert 1 type. This nucleus is a strong source of X-ray emission and undergoes variations in emission across the electromagnetic spectrum.
The source of the activity in this galaxy is a rapidly rotating supermassive black hole, which is located at the core and is surrounded by an accretion disk of dust. The estimated mass of this black hole is 8.7 million ([8.7 ± 1.1] × 106) times the mass of the Sun. Interferometric observations yield an inner radius of for the orbiting torus of dust.
This is a member of a loose association of 47 galaxies known as the NGC 3783 group. Located at a mean distance of 117 million light-years (36 Mpc), the group is centered at coordinates α = , δ = : equivalent to about from NGC 3783. The NGC 3783 group has a mean velocity of 2,903 ± 26 km/s with respect to the Sun and a velocity dispersion of 190 ± 24 km/s. The diffuse X-ray emission of the group is roughly centered on the galaxy NGC 3783.


HD 37646

HD 37646 is a double star in the northern constellation of Auriga. The pair have an angular separation of 26.005″.


HD 75898

HD 75898 is an 8th magnitude star approximately 255 light years away in the constellation Lynx. The star is 28% more massive, 60% larger, and 3 times as luminous than our local star. It is a metal-rich star, with 186% the solar abundance of iron. In 2007 the California and Carnegie Planet Search team found one planet orbiting HD 75898.
In 2019 the HD 75898 system was chosen as part of the NameExoWorlds campaign organised by the International Astronomical Union, which assigned each country a star and planet to be named. HD 75898 was assigned to Croatia. The winning proposal named the star Stribor, after the god of winds in Slavic mythology, and the planet Veles, after a deity of earth, water and the underworld in Slavic mythology.
Planetary system.
The planet HD 75898 b was discovered by the radial velocity method in 2007. At the time the centre of mass of the system appeared to be accelerating, indicating the presence of a third, more distant, component at least the size of Jupiter. Later additional monitoring however indicated that this long-period signal was likely a result of long-term magnetic activity on the parent star.


29 Cancri

29 Cancri is a star in the zodiac constellation of Cancer, located 370 light years from the Sun. It is just visible to the naked eye as a dim, white-hued star with an apparent visual magnitude of 5.94. The star is situated near the ecliptic, which means it is subject to lunar occultations.
This is an A-type main-sequence star with a stellar classification of A5 V, which indicates it is generating energy through hydrogen fusion at its core. It has 2.3 times the mass of the Sun and around 1.9 times the Sun's radius. The star has a relatively high rate of rotation, showing a projected rotational velocity of 117 km/s. It is radiating 45 times the Sun's luminosity from its photosphere at an effective temperature of 7,727 K.


Gamma Lyrae

Gamma Lyrae (Latinized from γ Lyrae, abbreviated Gamma Lyr, γ Lyr), formally named Sulafat , is the second-brightest star in the northern constellation of Lyra. With an apparent visual magnitude of 3.3, it is readily visible to the naked eye. Parallax measurements yield an estimated distance of from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of due to interstellar dust.
Nomenclature.
"γ Lyrae" (Latinised to "Gamma Lyrae") is the star's Bayer designation.
It bore the traditional names "Sulafat" ("Sulaphat"), from the Arabic "al-sulḥafāt" "turtle", and "Jugum", from the Latin "yoke". The connection with turtles is that fine harps were traditionally made of tortoiseshell. 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 "Sulafat" for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
In Chinese astronomy, (), meaning "Clepsydra Terrace", refers to an asterism consisting of this star, Delta2 Lyrae, Beta Lyrae and Iota Lyrae. Consequently, the Chinese name for Gamma Lyrae itself is (, .)
Properties.
This is a giant star with a stellar classification of B9 III, indicating it has exhausted the supply of hydrogen at its core and evolved away from the main sequence. The effective temperature of the outer envelope of this star is 10,080 K, giving it the blue-white hue typical of a B-type star. The interferometry-measured angular diameter of this star is , which, at its estimated distance, equates to a physical radius of roughly 15 times the radius of the Sun.
In 1909, Canadian astronomer Samuel A. Mitchell identified this star as a spectroscopic binary, although he was unable to split the absorption lines of the components. He found that a period of 25.6 days matched his measurements. It was reported as a spectroscopic binary as recently as 2001, but is now believed to be a single star with a high rate of rotation for stars of this type.
References.
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GSC 02620-00648

GSC 02620-00648 is a double star in the constellation Hercules. The brighter of the pair is a magnitude 12 star located approximately 1400 light-years away. This star is about 1.18 times as massive as the Sun.
Planetary system.
In 2006 the TrES program discovered exoplanet TrES-4 using the transit method. This planet orbits the primary star.
Binary star.
In 2008 a study was undertaken of 14 stars with exoplanets that were originally discovered using the transit method through relatively small telescopes. These systems were re-examined with the 2.2M reflector telescope at the Calar Alto Observatory in Spain. This star system, along with two others, was determined to be a previously unknown binary star system. The previously unknown secondary star is a dim magnitude 14 K or M-type star separated by about 755 AU from the primary, appearing offset from the primary by about one arc second in the images. This discovery resulted in a recalculation of parameters for both the planet and the primary star.


Eta Sagittarii

Eta Sagittarii (Eta Sgr, η Sagittarii, η Sgr) is a binary star system in the southern zodiac constellation of Sagittarius. Based upon parallax measurements, it is located at a distance of from Earth. It was formerly known as Beta Telescopii (β Tel). In India, where part of the constellation of Sagittarius represents an Elephant, this star forms the creature's tail.
The primary component, η Sagittarii A, is a red giant star with a stellar classification of M2 III. It is an evolved star that is currently at a stage called the asymptotic giant branch, having exhausted both the hydrogen and the helium at its core. This star is classified as an oxygen-rich irregular variable, as it undergoes small magnitude fluctuations between +3.08 and 3.12. The measured angular diameter of this star is . At the estimated distance of Eta Draconis, this yields a physical size of about 57 times the radius of the Sun.
The companion, η Sagittarii B, was first noted by American astronomer S. W. Burnham in 1879. The two stars share a common proper motion and hence are probably gravitationally bound to each other. The secondary is likely an F-type main sequence star with an apparent magnitude of +7.77. It located at an angular separation of 3.6 arcseconds from the primary, along a position angle of 108°. This star is at a projected distance of 165 Astronomical Units from the red giant primary and the pair take a minimum of 1,270 years to complete an orbit.
Within the context of the Milky Way galaxy, this system is a member of the faint old disk group. Because of proper motion, this star will move into constellation Corona Australis around 6300 CE. Eta Sagittarii has two optical companions that are not physically associated with the system. The first is a 10th magnitude star at an angular separation of 93 arcseconds with a position angle of 303°. There is a fainter, 13th magnitude star at an angular separation of 33 arcseconds along a position angle of 276°.
References.
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AT Microscopii

AT Microscopii is a binary star system located at a distance of from the Sun in the constellation of Microscopium. Both members are flare stars, meaning they are red dwarf stars that undergo random eruptions that increase their brightness. This pair lies physically near the red dwarf star AU Microscopii, which may mean they form a wide triple star system.
Observational history.
In 1926, Dutch-American astronomer Willem Jacob Luyten reported that the lines in the spectrum of this star underwent variation. A photographic plate taken on June 23, 1895, showed bright lines of hydrogen that were much weaker on a plate taken June 29, 1895. A photograph taken on July 1, 1903, showed no such lines. The net variation in brightness of the star was small, not exceeding 0.5 in magnitude. Luyten noted that the star has a large proper motion, changing its position by 0.43 seconds of arc between 1899 and 1923.
By 1927, the object was found to be a pair of stars with an angular separation of 2.95 arcseconds. Both were shown to be of 'dwarf Me' type, indicating they are red dwarfs with emission lines in their spectrum. This was the first such pair of matching dwarf Me stars to be discovered. The first parallax measurements of the pair showed an annual shift of about 0.1 arcseconds, while their radial velocity was measured to be +5 km/s away from the Sun. A nearby star HD 197981, later named AU Microscopii, was shown to have a similar radial velocity of +10 km/s. For this reason it was suggested that the three stars are physically associated.
Following the discovery in 1949 that certain types of variable stars are characterized by rapid but brief changes in brightness, accompanied by emission lines in their spectrum, in 1954 both HD 196982 A and B were listed as suspected flare stars by Czech solar physicist Zdeněk Švestka.
With the introduction of photometric instruments to astronomy, the variability of stars could now be monitored over intervals of time. Measurements of HD 196982 during 1969 showed them to be the most active flare stars known at that time: over a period of 16.31 hours, 54 flares were observed. The flares increased the combined magnitude of the pair by more than 0.05 for more than half of this observation period. By 1972, the pair had received the variable star designation AT Microscopii.
Properties.
Position measurements of the pair made with the Hipparcos spacecraft show an annual parallax shift of 0.0935 seconds of arc, which is equivalent to a distance of about from the Sun. It is a binary star system with an angular separation of 4.0 arcseconds. Both members are pre-main sequence, red dwarf stars and are among the youngest of this type in the neighborhood of the Sun. Relative to the Sun, component A has about 27% of the mass and 3.6% of the luminosity, while component B has 25% of the mass and 3.3% of the luminosity.
Both members of this system have active stellar coronae, show luminosity variations of the BY Draconis type, and are X-ray emitters. The average flare rate for the pair is 2.8 per hour. Their X-ray spectrum is consistent with a plasma density of around and a magnetic field strength of at least 100 G in the flare regions. Neither star shows any indication of lithium in their spectrum, having depleted this element through nuclear fusion at their cores.
This binary system is located in close proximity to the young star AU Microscopii, with a projected separation of . This indicates that the three may form a wide hierarchical triple system, with the AT Microscopii pair orbiting AU Microscopii over a period of 10 million years. All three stars are candidate members of the Beta Pictoris moving group, one of the nearest associations of stars that share a common motion through space. This group averages a distance of about from the Earth, but are scattered across a volume roughly in diameter. Estimates for the age of this group range between 10 and 21 million years.


Sigma Herculis

Sigma Herculis, Latinized from σ Her, is a binary star system in the northern constellation of Hercules. It has a combined apparent visual magnitude of 4.18, making it bright enough to be visible to the naked eye. Based upon an annual parallax shift of 10.36 mas as seen from Earth, Sigma Herculis is located about 310 light years away from the Sun.
The components of this binary system have a separation of 7 AU, and are orbiting their common barycenter with a period of 7.4 years and an eccentricity of 0.5. The primary, component A, is magnitude 4.20 B-type main sequence star with a stellar classification of B9 V. At an age of around 404 million years, it is spinning rapidly with a projected rotational velocity of 280 km/s. This is giving the star an oblate shape with an equatorial bulge that is an estimated 18% larger than the polar radius. The star has an estimated 2.60 times the mass of the Sun, 4.91 times the Sun's radius, and is radiating 230 times the solar luminosity from its photosphere at an effective temperature of 9,794 K.
The primary is emitting an infrared excess, suggesting the presence of an orbiting debris disk with a temperature of 80 K located at a radius of 157 AU. There may be a second disk orbiting between 7 and 30 AU with a temperature of . The Poynting–Robertson lifetime of the dust grains in this inner belt is around 46,000 years − much less than the age of the star. Hence the grains are being replenished, presumably through collisions between larger objects. Circumstellar gas is visible in ultraviolet images from the FUSE satellite, which is likely being emitted by the circumstellar matter then driven outward by the star's radiation.
The secondary, component B, has a magnitude of 7.70 and is an A-type main-sequence star. It has around 1.5 times the mass of the Sun and 7.4 times the Sun's luminosity.


NGC 4500

NGC 4500 is a barred spiral galaxy in the constellation Ursa Major. The galaxy was discovered on April 17, 1789 by William Herschel. It is a blue compact galaxy.
Its distance from Earth is approximately 50 million parsecs.


NGC 4343

NGC 4343 is an unbarred spiral galaxy in the constellation Virgo. It was discovered by the astronomer William Herschel on April 13, 1784. At a distance of 80 million light-years (25 Mpc), it is located in the Virgo Cluster. It contains an active galactic nucleus.


RCW 38

RCW 38 is an HII region containing a massive star cluster located approximately 5,500 light years away from Earth in the direction of the constellation Vela (known as the Sails). The stars were very recently formed, and are still enshrouded within the dark cloud in which they were born. The star cluster is surrounded by clouds of brightly glowing gas and is composed of several short-lived massive stars, hundreds of young stars, and many protostars.
The star cluster several O-type stars with masses much larger than the sun. When these stars die, likely before the dispersal of the cluster, they will explode as supernovae.
RCW 38 includes Gum 22, Gum 23, and Gum 24.
Star Cluster.
Observations by the Chandra X-ray Observatory have revealed more than 800 X-ray emitting young stellar objects in the cluster.
The star cluster was also observed during testing of the HAWK-I camera, which revealed many details within the cluster that previously were obscured.