66 Eridani

66 Eridani is a binary star in the constellation of Eridanus. The combined apparent magnitude of the system is 5.12 on average. Parallax measurements by Hipparcos put the system at some 309 light-years (95 parsecs) away.
This is a spectroscopic binary: the two stars cannot be individually resolved, but periodic Doppler shifts in its spectrum mean there must be orbital motion. The two stars orbit each other every 5.5226013 days. Their orbit is fairly eccentric, at 0.0844.
The combined spectrum of 66 Eridani matches that of a B-type main-sequence star, and the two stars have similar masses. The spectrum also shows excess of mercury and manganese, as it is a type of chemically peculiar star called a mercury-manganese star. 66 Eridani is an Alpha2 Canum Venaticorum variable. For this reason, it has been given the designation EN Eridani.


Pi Cancri

The Bayer designation π Cancri (Pi Cancri) is shared by two stars in the constellation Cancer:
See also.
ρ Cancri


Epsilon Sextantis

Epsilon Sextantis, Latinized from ε Sextantis, is a solitary, yellow-white hued star in the equatorial constellation of Sextans. With an apparent visual magnitude of 5.24, it is faintly visible to the naked eye on a dark night. The distance to this star, based upon an annual parallax shift of 16.86 mas, is about 193 light years. It is drifting further away from the Sun with a radial velocity of +15 km/s.
This is an F-type subgiant star with a stellar classification of F0 IV. However, Malaroda (1975) gave a classification of F2 III, which would indicate a more evolved giant star. It is estimated to have nearly double the mass of the Sun with 3.1 times the Sun's radius. The star is around 1.1 billion years old and has a projected rotational velocity of 63.5 km/s. It is radiating 23 times the luminosity of the Sun from its photosphere at an effective temperature of 7,166 K.


HD 220689

HD 220689 is a single star in the equatorial constellation of Aquarius. It is a challenge to view with the naked eye, having an apparent visual magnitude of +7.74, but is readily viewed with a pair of binoculars. The star is located at a distance of 153 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +12 km/s. A survey in 2015 has ruled out the existence of any additional stellar companions at projected distances from 26 to 305 astronomical units.
The stellar classification of HD 220689 is G3V, matching a yellow hued G-type main-sequence star that is generating energy through core hydrogen fusion. It is roughly 4.6 billion years old and is spinning with a projected rotational velocity of 5.5 km/s, giving it a rotation period of around 29 days. The star has a similar size, mass, and elemental abundances as the Sun. It is radiating 1.5 times the luminosity of the Sun from its photosphere at an effective temperature of 5,921 K.
Planetary system.
From 1998 to 2012, the star was under observation from the CORALIE echelle spectrograph at La Silla Observatory. In 2012, a long-period, wide-orbiting exoplanet was deduced from radial velocity variations. This was published in November. The maximum orbital period allowing for dynamic stability of a hypothetical inner planet is .


36 Tauri

36 Tauri (abbreviated to 36 Tau) is a binary star in the constellation of Taurus. Parallax measurements made by the Hipparcos spacecraft put it at a distance of over 1,000 light years (350 parsecs) from Earth. The combined apparent magnitude of the system is about 5.5, meaning it can barely be seen with the naked eye, according to the Bortle scale.
36 Tauri is a spectroscopic binary. The two stars are close enough that periodic Doppler shifts in their spectra can be made out. In this case, light from both stars can be detected (and they overlap in the spectrum), so it is a double-lined system. The primary star, designated HD 25555, is a K-type bright giant, and the secondary star, designated HD 25556, is a B-type main-sequence star. However, the spectrum has also been interpreted as a G-type star and an A-type main-sequence star. The two stars have been resolved using speckle interferometry and are thought to have similar masses.


NGC 296

NGC 296 is a low surface brightness unbarred spiral galaxy in the constellation of Pisces. The designation NGC 295 is sometimes mistakenly used for NGC 296.


NGC 2539

NGC 2539 is an open cluster in the constellation Puppis, located at the north edge of the constellation. It was discovered by William Herschel on January 31, 1785. It is a moderately rich cluster and with little central concentration, with Trumpler class II1m.
Characteristics.
The diameter of the cluster based on the location of possible members is estimated to be 7.4 parsecs (24 light years). The core radius of the cluster is 1.98 parsecs (6.5 light years), while the tidal radius is 15.2 parsecs (50 light years) and represents the average outer limit of NGC 2539, beyond which a star is unlikely to remain gravitationally bound to the cluster core.
151 stars, probable members of the cluster, are located within the central part of the cluster and 455 probable members are located within the angular radius of the cluster. 19 Puppis, visible near the edge of the cluster is a foreground star. The turn-off mass of the cluster is at 3.1 . The metallicity of the cluster is 0.14, higher than the solar one. The age of the cluster has been estimated to be as high as 630 myrs.
Mermilliod and Mayor studied 11 red giants within the cluster, the brightest of which was mag 9.509 and of spectral type K5I-II, and two non-members. Three of this stars were found to be spectrographic binaries, while further studies indicated that one of them is a triple system. Two more are suspected double stars. Further studies revealed seven variable stars, 5 eclipsing binaries, one delta Scuti variable and one gamma Doradus variable, with the gamma Doratus variable star membership being questionable. From the eclipsing binaries, one is field star and in a further study one more eclipsing binary (specifically a W Ursae Majoris variable) was found to lie at the background.


Omicron2 Canis Majoris

Omicron2 Canis Majoris (ο² CMa, ο² Canis Majoris) is a star in the constellation Canis Major. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It has an apparent visual magnitude of 3.043, making it one of the brighter members of the constellation. The distance to this star is roughly 2,800 light years (800 parsecs), with a 34% margin of error.
Properties.
This is a massive supergiant star with a stellar classification of B3 Ia, indicating that, at the age of around 7 million years, it has exhausted the supply of hydrogen at its core and is now undergoing nuclear fusion of helium to generate energy. It has about 21 times the mass of the Sun and 65 times the Sun's radius. In all likelihood, it will end its life as a Type II supernova.
Omicron2 Canis Majoris is one of the most luminous stars known, as it radiates about 220,000 times as much luminosity as the Sun from its outer envelope at a temperature of 15,500 K. At this heat, the star is glowing with the blue-white hue of a B-type star. This star is classified as an Alpha Cygni-type variable star that undergoes periodic non-radial pulsations, which cause its brightness to cycle from magnitude +2.93 to +3.08 over a 24.44 day interval. It is losing mass from its stellar wind at the rate of around times the mass of the Sun per year, or the equivalent of the Sun's mass every 500 million years.
Collinder 121.
While this star lies in the field of view of the open cluster named Collinder 121, it is unlikely to be a member. In fact, its optical neighbor, the orange supergiant ο1 Canis Majoris has a much higher likelihood of 23.1% based upon its proper motion being a closer match to the motion of the cluster. Although they are located near each other on the celestial sphere, ο1 CMa and ο2 CMa are most likely not gravitationally bound to each other as they appear to lie many light years apart.
Name.
In the catalogue of stars in the "Calendarium of Al Achsasi Al Mouakket", this star was designated Thanih al Adzari (ثاني ألعذاري - "thaanii al-aðārii"), which was translated into Latin as Secunda Virginum, meaning "the second virgin". This star, along with ε CMa (Adhara), δ CMa (Wezen) and η CMa (Aludra), were Al ʽAdhārā (ألعذاري), the Virgins.


Psi Lupi

The Bayer designation Psi Lupi (ψ Lup / ψ Lupi) is shared by two stars, in the constellation Lupus:


S Eridani

The Bayer designation s Eridani and the variable star designation S Eridani are distinct. Due to , both designations link here. For the star


39 Cancri

39 Cancri is a star in the constellation Cancer, located about 614 light years from the Sun in the Beehive Cluster (NGC 2632). It is a challenge to see with the naked eye, having an apparent visual magnitude of 6.39. This object is moving further from the Earth with a heliocentric radial velocity of 34 km/s.
This is an evolved giant star with a stellar classification of G8+ III-IIIb, indicating it has consumed the hydrogen at its core. It is 460 million years old with 2.88 times the mass of the Sun and about 12 times the Sun's radius. The star is radiating 105 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,954 K.


GCIRS 8*

GCIRS 8* (Galactic Centre IRS 8*) is a young massive star in the Galactic Center region, discovered in May 2006. "IRS 8" is an infra-red source identified as a bowshock. The star causing the bowshock has been classified as an O5-O6 giant or supergiant several hundred thousand times as luminous as the sun. It is estimated to be 3.5 million years old, although if it is a binary then it would probably be older. The mass is estimated at .


Omega2 Tauri

Omega2 Tauri is a solitary, white hued star in the zodiac constellation of Taurus. It has an apparent visual magnitude of +4.9, which is bright enough to be seen with the naked eye at night. The distance to this system, as determined using an annual parallax shift of 34.55 mas as seen from the Earth, is about 94 light years.
This is a young Am star with an age of around 100 million years and a stellar classification of A3m. It displays an infrared excess emission, indicating the presence of an orbiting debris disk with a mean temperature of 99 K. This star is a probable member of the Octans Near association, a nearby moving group of stars that share a common motion through space.


Tau Centauri

Tau Centauri, Latinized from τ Centauri, is a solitary star in the southern constellation of Centaurus. It is visible to the naked eye with an apparent visual magnitude of +3.86. The distance to this star, based upon an annual parallax shift of 24.85 mas, is 131 light years. There is a 98% chance that it is a co-moving companion of Gamma Centauri; the two stars have an estimated separation of .
This is an A-type star with stellar classifications of A0 V or A1 IVnn, indicating it may be a main sequence star or a more evolved subgiant star. It is around 132 million years old and is spinning rapidly with a projected rotational velocity of 296.8 km/s. This is giving the star an oblate shape, with an estimated equatorial girth that is 30% larger than the polar radius. The star has an estimated 2.3 times the mass of the Sun and 2.2 times the Sun's radius.


NGC 4320

NGC 4320 is a peculiar galaxy located about 370 million light-years away in the constellation Virgo. It was discovered by astronomer Heinrich d'Arrest on April 15, 1865 and is a member of the NGC 4325 Group.
NGC 4320 appears to be the end result of an interaction and merger of two spiral galaxies.


78 Pegasi

78 Pegasi is a binary star system in the northern constellation of Pegasus. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.93. The system is located approximately 224 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −8 km/s. The double-star nature of this system was discovered by A. G. Clark in 1862. The components of this system orbit each other over a 630-year period with an eccentricity of 0.11.
The primary member, designated component A, is a magnitude 5.07 giant star with a stellar classification of K0III, having exhausted the supply of hydrogen at its core and expanded to 10 times the Sun's radius. It is a red clump giant, which indicates it is on the horizontal branch and is generating energy through core helium fusion. It has 1.5 times the mass of the Sun and is radiating 57 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,898 K. The secondary companion, component B, is magnitude 8.10.


NGC 7052

NGC 7052 is an elliptical galaxy in the constellation Vulpecula. The galaxy harbours a supermassive black hole with mass c. 220-630 million solar masses in its nucleus.


V Hydrae

V Hydrae (V Hya) is a carbon star in the constellation Hydra. To date perhaps uniquely in our galaxy it has plasma ejections/eruptions on a grand scale every 8.5 years caused by its near, unseen companion in an 8.5 year orbit, inferred by its ultraviolet excess and periastron passage likely through the outer parts of the star itself.
Variability.
V Hydrae is a semiregular variable star of type SRa, sometimes considered to be a Mira variable. It pulsates with a period of 530 days and a brightness range of 1-2 magnitudes, but also shows deep fades at intervals of about 6,160 days when it may drop below magnitude 12.
Evolutionary stage.
V Hydrae is a late carbon star, an asymptotic giant branch (AGB) star that has dredged up sufficient material from its interior to have more carbon in its atmosphere than oxygen. The rate of mass loss from V Hydrae indicates that it is almost at the end of the AGB stage and about to lose its atmosphere completely and form a planetary nebula. It is sometimes considered to be a post-AGB object.
Companions.
V Hydrae has a visible binary companion 46" distant. It is a magnitude 11.5 K0 giant.
V Hydrae also has an unseen companion in an 8.5 year orbit, inferred by its ultraviolet excess and eruptions associated with the periastron passage. It has been suggested that the steep drops in brightness every 17 years or so are caused by obscuration by a cloud associated with the companion passing in front of the giant star.
Bullets.
V Hydrae has high-speed outflows of material collimated into jets, and also a disk of material around the star. Since the star itself is considered to be at the end of the Asymptotic Giant Branch (AGB) phase of evolution and starting to generate a planetary nebula, the mechanism for the ejection of this material can give key insights to the formation of planetary nebulae. The ejections have been modelled as "bullets" of material fired out each time the compact companion passes close to the extended giant star during a highly eccentric orbit. The bullets are ejected in opposite directions in different orbits due to a flip-flop of the ejection mechanism. Microwave spectra of rotational transitions of carbon monoxide show that portions of the envelope, probably the jets, are moving away from the star at 200 km/sec. This is far faster than the ~15 km/sec stellar wind that is typically seen around AGB stars.


HR 7578

HR 7578 (also known as V4200 Sagittarii) is a binary star in the constellation of Sagittarius. Their combined apparent magnitude is 6.18. Parallax measurements by the Gaia spacecraft put the system at 46.01 light-years (14.107 parsecs) away, making this a nearby system.
The two stars of HR 7578 are fairly old, older than the Pleiades but possibly younger than the Hyades. The stars are between and years old. Both are K-type main-sequence stars. Both stars have a minimum mass of , and are unusually metal-rich, showing high amounts of cyanide and sodium in their spectra.
HR 7578 is a BY Draconis variable. This is a class of variable star whose variability comes from starspots on the stars' surfaces. HR 7578 also has a common proper motion companion, 2MASS J19542064−2356398. It is a red dwarf that is at least 580 astronomical units from the central star system.


HD 222093

HD 222093 is a double star in the equatorial constellation of Aquarius. It has an orange hue and is visible to the naked eye with an apparent visual magnitude of 5.68. The system is located at a distance of approximately 293 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −13 km/s.
The primary component is an aging K-type giant star with a stellar classification of K0III, which indicates it has exhausted the supply of hydrogen at its core then cooled and expanded. At present it has ten times the Sun's radius. This is a red clump giant, which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. It is around three billion years old with 1.5 times the mass of the Sun. The star is radiating fifty times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,853 K.
According to Eggleton and Tokovinin (2008), this is most likely a wide binary star system; the secondary companion is a magnitude 9.6 star at an angular separation of from the primary. However, the "Washington Visual Double Star Catalog" gives a magnitude of 11.19 with an angular separation of .


HR 7722 b

HR 7722 b is an exoplanet orbiting the star HR 7722. It orbits its parent star with a semimajor axis of 0.32 ± 0.005 AU, an eccentricity of 0.13 ± 0.04. and an orbital period of 74.72 days.
The Neptune-sized planet has at least 21 times the mass of Earth and 3 to 4 times its diameter.
HR 7722 b was discovered on 1 November 2010 and lies within the inner edge of the habitable zone of HR 7722.


S Microscopii

S Microscopii is a star in the constellation Microscopium. It is a red giant star of spectral type M3e-M5.5 that is also a Mira variable, with an apparent magnitude ranging between 7.4 and 14.8 over 210 days. The Astronomical Society of Southern Africa in 2003 reported that observations of S Microscopii were very urgently needed as data on its light curve was incomplete.


49 Ceti

49 Ceti is a single star in the equatorial constellation of Cetus. It is visible to the naked eye as a dim, white-hued star with an apparent visual magnitude of 5.607. The star is located away from the Solar System, based on its parallax, and is drifting further away with a radial velocity of +10 km/s. 49 Ceti has been identified as a member of the 40-million-year-old Argus Association.
This is a young A-type main-sequence star with a stellar classification of A1V. It is about 40 million years old with a high rate of spin, showing a projected rotational velocity of 196 km/s. The star has double the mass of the Sun. It is radiating 19 times the Sun's luminosity from its photosphere at an effective temperature of 8,790 K.
49 Ceti displays a significant infrared excess, which is a characteristic of a debris disk orbiting the star. Unusually, the disk seems to be gas-rich, with evidence of carbon monoxide (CO) gas. This carbon monoxide gas may possibly be from comets orbiting the star within the disk, similar to the Kuiper Belt in the Solar System.


KZ Andromedae

KZ Andromedae (often abbreviated to KZ And) is a double lined spectroscopic binary in the constellation Andromeda. Its apparent visual magnitude varies between 7.91 and 8.03 during a cycle slightly longer than 3 days.
System.
Both stars in the KZ Andromedae system are main sequence stars of spectral type K2Ve, meaning that the spectrum shows strong emission lines. This is caused by their active chromospheres that cause large spots on the surface.
KZ Andromedae is listed in the Washington Double Star Catalog as the secondary component in a visual binary system, with the primary being HD 218739. In 50 years of observations, there is little evidence of relative motion between the two stars; however, they have a common proper motion and a similar radial velocity.
Variability.
The rotational velocity of both stars is consistent with a synchronous rotation of the pair, and the rotational period is itself comparable to the brightness variation period. KX Andromedae is thus classified as a BY Draconis variable, and the variability is caused by the large spots on the surface.


Westerlund 2

Westerlund 2 is an obscured compact young star cluster (perhaps even a super star cluster) in the Milky Way, with an estimated age of about one or two million years. It contains some of the hottest, brightest, and most massive stars known. The cluster resides inside a stellar breeding ground known as Gum 29, located 20,000 light-years away in the constellation Carina. It is half a degree from the naked eye Cepheid variable V399 Carinae.
Cluster members.
The cluster contains at least a dozen early O stars, of which at least three are eclipsing binaries. All are hotter than 38,000 K and more luminous than . There are around 20 further O class stars in the cluster, all main sequence objects implying a very young age for the cluster.
Several Wolf–Rayet stars are found in the vicinity of Westerlund 2, although not in the central core. WR20a, a binary consisting of two WR stars, and the single stars WR20aa, WR20b, and WR20c are all thought to be members of the cluster, although possibly now runaway members. All five Wolf Rayets are extremely young massive objects with OIf*/WN spectral types, amongst the most luminous stars in the galaxy. This composite spectral type indicates young very massive hydrogen-burning stars that are just starting to convect nitrogen and helium to the surface and develop denser stellar winds so that they show the emission lines of a Wolf-Rayet star. WR21a, itself a massive binary, lies in the same direction but is unlikely to be a member of Westerlund 2.
Westerlund 2 also contains a large number of pre-main sequence stars with masses below . These stars constrain the age of the cluster to near 2 Myr.
Discovery.
As its name indicates, the Westerlund 2 cluster was discovered by Bengt Westerlund in the 1960s but its stellar content was assessed only in later years.
Hubble 25th Anniversary Image.
On 23 April 2015 an image of the Westerlund 2 cluster was chosen to celebrate the 25th anniversary of the Hubble Space Telescope.


59 Sagittarii

59 Sagittarii is a single star in the southern constellation of Sagittarius, about a degree to the south of Omega Sagittarii near the constellation border with Capricornus. It has the Bayer designation b Sagittarii, or sometimes b1 Sagittarii, while "59 Sagittarii" is the Flamsteed designation. The star is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.544. It forms the southeast corner of the asterism called the Terebellum. Based upon parallax measurements, the star is located approximately 830 light years away from the Sun. It is moving closer to the Earth with a heliocentric radial velocity of −16 km/s.
This is an aging bright giant star with a stellar classification of K2.5IIb, having exhausted the supply of hydrogen at its core and expanded to 100 times the radius of the Sun. It is 64 million years old with 6.2 times the Sun's mass. The star is radiating 2,825 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,204 K.


R Sculptoris

R Sculptoris is a variable star system in the southern constellation of Sculptor. Parallax measurements provide a distance estimate of approximately from the Sun. An independent estimate based on measurements of an ejected shell surrounding the star yield a distance of . The star is drifting closer with a radial velocity of −5.4 km/s.
This is an aging giant star on the asymptotic giant branch with a stellar classification of C6,5ea(Np), which indicates a carbon-rich atmosphere. It is a semi-regular pulsating star of the SRb type that is nearing the end of its fusing lifespan. A sine curve fitted to the last ten pulsation cycles prior to 2017 give a pulsation period of 376 days with an amplitude of 0.75 magnitude. The star is shedding its outer atmosphere, and it is surrounded by a thin shell of dust and gas that was created during the most recent thermal pulse around 2,000 years ago.
Observations have revealed a spiral structure in the material around the star. The spiral is suspected to be caused by an unseen companion star. The spiral windings are consistent with an orbital period of ~350 years.


Chi Cassiopeiae

Chi Cassiopeiae (χ Cassiopeiae) is a solitary, yellow-hued star in the constellation Cassiopeia. It is visible to the naked eye with an apparent visual magnitude of +4.7. Based upon an annual parallax shift of 15.67 mas as seen from Earth, this system is located roughly 208 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.18 due to interstellar dust.
With a stellar classification of G9 IIIb, it has the spectrum of an evolved, G-type giant star. It has an estimated age of a billion years and is a red clump star that it is generating energy through helium fusion at its core. The star has about double the mass of the Sun and has expanded to 11 times the Sun's radius. It is radiating 67.6 times the Sun's luminosity from its photosphere at an effective temperature of 4,746 K.


NGC 5755

NGC 5755 is a barred spiral galaxy in the constellation Boötes, member of Arp 297 interacting galaxies group of four: NGC 5752, NGC 5753, NGC 5754, and NGC 5755.


Epsilon Cancri

Epsilon Cancri (ε Cancri, abbreviated Epsilon Cnc, ε Cnc) is a white-hued binary star system in the zodiac constellation of Cancer. It is the brightest member of the Beehive Cluster with an apparent visual magnitude of +6.29, which is near the lower limit of visibility with the naked eye. The annual parallax shift of as seen from Earth yields a distance estimate of approximately 616 light-years from the Sun.
The binary pair has the designation WDS J08405+1933. The primary star is designated Epsilon Cancri and the secondary is HD 73711. Epsilon Cancri is itself a spectroscopic binary with components designated Aa (also named Meleph) and Ab. HD 73711 is itself suspected of being a spectroscopic binary.
Nomenclature.
"ε Cancri" (Latinised to "Epsilon Cancri") is the system's Bayer designation (which originally referred to the entire cluster).
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 "Meleph" for the component Epsilon Cancri Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
Properties.
The system is moving away from the Sun with a radial velocity of +30 km/s.
Epsilon Cancri A is a double-lined spectroscopic binary system with an orbital period of 35 days and eccentricity of 0.32. It has a stellar classification of A5 III, which matches an A-type giant star. The spectrum displays the chemically peculiar characteristics of an Am star. Its spectral type has been listed as kA3hA5mF0, indicating the different spectral types shown by spectral lines of calcium, hydrogen, and other metals. The age of the system is estimated to be around 729 million years.
HD 73711 is another Am star F-type star with a stellar classification of F0 III.


Iota2 Normae

ι2 Normae, Latinised as Iota2 Normae, is a single, blue-white star located in the southern constellation of Norma. It is positioned to the west of Rigil Kentaurus but can be difficult to spot against the Milky Way. It is faintly visible to the naked eye with an apparent visual magnitude of +5.57. Measuring its parallax reveals it is located away from the sun. At that distance, the visual magnitude is diminished by an interstellar extinction factor of 0.24 due to intervening dust. The radial velocity of this star is zero, indicating it is neither moving toward nor away from the Sun.
Iota2 Normae is a B-type main-sequence star with a stellar classification of B9.5 V. It is larger than the Sun with 2.6 times the mass of the Sun and about 3.1 times the Sun's radius. The star is estimated to be 257 million years old and is spinning with a projected rotational velocity of 111 km/s. It is radiating approximately 40 times the Sun's luminosity from its photosphere at an effective temperature of 10,593 Kelvin.


NGC 3464

NGC 3464 is a barred spiral galaxy in the constellation of Hydra, discovered 14 January 1886 by Ormond Stone.
Supernovae.
Two supernovae were observed in NGC 3464 in 2002. SN 2002J, a Type Ic supernova, was detected 21 January, and SN 2002hy, a Type Ib supernova, was detected 12 November. A Type Ia supernova, SN 2015H, was first observed 10 February 2015.


HD 99706

HD 99706 is an orange-hued star in the northern circumpolar constellation of Ursa Major. With an apparent visual magnitude of 7.65, it is too dim to be visible to the naked eye but can be viewed with a pair of binoculars. Parallax measurements provide a distance estimate of approximately 480 light years from the Sun, and the Doppler shift shows it is drifting closer with a radial velocity of −30 km/s. It has an absolute magnitude of 2.12, indicating it would be visible to the naked eye as a 2nd magnitude star if it were located 10 parsecs away.
This is an aging subgiant star belonging to spectral class K0, having exhausted the supply of hydrogen at its core and begun to evolve into a giant. Its age is younger than the Sun's at billion years and it is spinning slowly with a projected rotational velocity of 2 km/s. The star has 1.5 times the mass of the Sun and has expanded to 5.5 times the Sun's radius. It is slightly enriched in heavy elements, having 110% of solar abundance. HD 99706 is radiating 13 times the luminosity of the Sun from its photosphere at an effective temperature of 4,862 K.
An imaging survey at Calar Alto Observatory in 2016 failed to detect any stellar companions to HD 99706.
Planetary system.
In 2011 one superjovian exoplanet, HD 99706 b, on a mildly eccentric orbit around star HD 99706 was discovered utilizing the radial velocity method. Another superjovian exoplanet on an outer orbit was detected in 2016.


Pistol Star

The Pistol Star is an extremely luminous blue hypergiant star, one of the most luminous and massive known in the Milky Way. It is one of many massive young stars in the Quintuplet cluster in the Galactic Center region. The star owes its name to the shape of the Pistol Nebula, which it illuminates. It is located approximately 25,000 light years from Earth in the direction of Sagittarius. The star has a large mass comparable to the V4998 Sagittarii and a luminosity ten million times the Sun (). It would be visible to the naked eye as a fourth magnitude star if it were not for the interstellar dust that completely hides it from view in visible light.
Properties.
The Pistol Star was discovered using the Hubble Space Telescope in the early 1990s by Don Figer, an astronomer at UCLA.
The star is thought to have ejected almost 10 solar masses of material in giant outbursts perhaps 4,000 to 6,000 years ago (as observed from Earth). Its stellar wind is over 10 billion times stronger than the Sun's. Its exact age and future are not known, but it is expected to end in a brilliant supernova or hypernova in 1 to 3 million years. The mass is equally uncertain, thought to have been up to 200 times the Sun when initially formed but now considerably less due to extreme mass loss although likely still over 100 times the Sun. Modelling the star itself to match its spectrum gives a mass of , while matching its current properties to an evolutionary model gives a much higher mass (). Earlier studies once claimed the Pistol Star as the most massive star known at around .
Later studies have reduced its estimated luminosity making it a candidate luminous blue variable about (one-third as luminous as the binary star system Eta Carinae), hence a radius of based on an effective temperature around , or as high as , hence a correspondingly radius of . Even so, it radiates about as much energy in 20 seconds as the Sun does in a year.
A close point source has been discovered hidden in the surrounding nebulosity, but there has been no confirmation of this being a star or whether it is physically associated.


NGC 3593

NGC 3593 is a lenticular galaxy located in the constellation Leo. It has a morphological classification of SA(s)0/a, which indicates it is a lenticular galaxy of the pure spiral type. This is a starburst galaxy, which means it is forming new stars at a high rate. This is occurring in a band of gas surrounding the central nucleus. There is a single arm, which spirals outward from this ring. It is frequently but not consistently identified as a member of the Leo Triplet group.
This galaxy is known to contain two counter-rotating populations of stars. That is, one set of stars is rotating in the opposite direction with respect to the other. One means for this to occur is by acquiring gas from an external source, which then undergoes star formation. An alternative is by a merger with a second galaxy. Neither scenario has been ruled out. The age of the lower mass, counter-rotating population is younger by about than the primary star population of the galaxy.


Lambda Persei

λ Persei, Latinized as Lambda Persei, is a star in the northern constellation of Perseus. It is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.29. This object is located approximately 422 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +6 km/s.
This object has a stellar classification of A0IVn, matching an A-type subgiant star with "nebulous" lines due to rapid rotation. It is spinning with a projected rotational velocity of 196 km/s, which is giving the star an equatorial bulge that is an estimated 16% larger than the polar radius. Unusually for a star of this type, spectra show weak emission features among the Hydrogen lines, which may be due to plage regions on the surface caused by an implied magnetic field. The star is 345 million years old and is radiating 348 times the luminosity of the Sun from its photosphere at an effective temperature of 10,585 K.
In Chinese astronomy, Lambda Persei is called 積水, Pinyin: Jīshuǐ, meaning "Stored Water", because this star is marking itself and stand alone in "Stored Water" asterism, Stomach mansion (see : Chinese constellation).


Omicron2 Orionis

Omicron2 Orionis (ο2 Ori) is a solitary star in the constellation Orion. It has an apparent visual magnitude of 4.06, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 17.54 mas, it is around 186 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an interstellar absorption factor of 0.09 due to intervening dust.
This is a red clump giant star with a stellar classification of K2 IIIb. It is around 5.4 billion years old with a projected rotational velocity that is too small to be measured. The star has expanded to about 15 times the radius of the Sun and shines with 79 times the solar luminosity from its outer atmosphere at an effective temperature of 4,498 K. Omicron2 Orionis is most likely a member of the Milky Way's thin disk population.


R Scuti

R Scuti ("R Sct") is a star in the constellation of Scutum. It is a yellow supergiant and is a pulsating variable known as an RV Tauri variable. It was discovered in 1795 by Edward Pigott at a time when only a few variable stars were known to exist.
Observation.
R Sct is the brightest of the RV Tau-type stars and the American Association of Variable Star Observers (AAVSO) contains over 110,000 observations of this star. At its brightest it is visible to the naked eye, and at its dimmest can be located with good binoculars. In the sky it is about 1 degree northwest of the Wild Duck Cluster (Messier 11).
RV Tauri variables often have somewhat irregular light curves, both in amplitude and period, but R Scuti is extreme. It has one of the longest periods known for an RV Tau variable, and the light curve has a number of unusual features: occasional extreme minima; intermittent standstills with only small erratic variation that may last for years; and periods of chaotic brightness changes.
Properties.
The spectrum of R Scuti is peculiar, especially at cooler temperatures near the minima. In deep minima, much of the spectrum corresponds to an early K supergiant, but the spectrum also develops TiO bands more typical of an M-class star.
The recognised spectral type of G0Iae-K2p(M3)Ibe gives an idea of the complexities of this star. Both the radius and temperature change, with maximum brightness corresponding to maximum temperature. The radius changes lag and the smallest size occurs about a quarter of the period after the minimum brightness.
The spectral luminosity type classes R Sct as a supergiant, a bright supergiant (class Ia) near maximum, but it is actually thought to be a highly evolved and expanded low-mass star probably no more than 10,000 times the luminosity of the sun even at its brightest. The period-luminosity relation for type II Cepheids suggests a luminosity of , similar to the spectrophotometric derivation at . Other derivations have produced much lower values, but often making unrealistic assumptions about the distance based on an obsolete Hipparcos parallax value.
An extreme post-AGB star would be expected to show measurable secular changes in its temperature and period over the time that R Scuti has been closely observed. Instead a relatively low mass loss rate with an extended cool atmosphere and fairly constant temperature and period of variation is seen. One suggestion is that R Scuti is still a thermally pulsing AGB star, consistent with calculated levels of mass loss.
The evolutionary status of R Scuti is uncertain and estimates of the mass vary wildly. RV Tau variables as post-AGB stars are expected to have masses near or below that of the sun and this is confirmed for a number of RV Tau stars in binary systems. Old estimates based simply on the supergiant luminosity class gave much higher masses.


Zeta Cancri

Zeta Cancri (ζ Cancri, abbreviated Zeta Cnc, ζ Cnc) is a multiple star system in the constellation of Cancer. It is approximately 83.4 light-years from Earth, and has a combined apparent magnitude of +4.67. Since it is near the ecliptic, it can be occulted by the Moon and, very rarely, by planets.
The system is constituted as follows:
Nomenclature.
"ζ Cancri" (Latinised to "Zeta Cancri") is the system's Bayer designation; "ζ¹ Cancri" and "ζ² Cancri" those of its two constituents. The designations of the two constituents as "ζ Cancri AB" and "C", and those of their components - "ζ Cancri A", "B", "Ca", "Cb", "Cb1" and "Cb2" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Considerable confusion had developed concerning the catalogue identities of the three bright stars; correct correspondences were worked out by Griffin:
"Zeta Cancri" bore the traditional name "Tegmine" ("Tegmen") "the shell (of the crab)". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name "Tegmine" for the component "Zeta¹ Cancri A" on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Water Level", refers to an asterism consisting of Zeta Cancri, 6 Canis Minoris, 11 Canis Minoris and 8 Cancri. Consequently, Zeta Cancri itself is known as (, ).
Properties.
Zeta Cancri can be resolved as a binary star in small telescopes. Its binary nature was discovered in 1756 by Tobias Mayer. William Herschel resolved the two components that make up Zeta¹ Cancri in 1781. As early as 1831, John Herschel noticed perturbations in Zeta² Cancri's orbit around Zeta¹; this led Otto Wilhelm von Struve, in 1871, to postulate a fourth, unseen, component which orbited closely the visible member of Zeta². Later observations have resolved this fourth component and have indicated that there may be one or two more unobserved components.
Zeta¹ and Zeta² Cancri are 5.06 arcseconds apart. These two star systems orbit around their common centre of mass once every 1100 years. The radius is about 6.80.
Zeta¹ Cancri.
The two components are both yellow-white main sequence dwarfs of spectral class F. The apparent magnitudes of A and B are +5.58 and +5.99, respectively. They are separated, as of 2008, by 1 arcsecond, requiring a large telescope to resolve them, but this separation will increase until the year 2020. They complete one orbit every 59.6 years. The estimated masses for the pair are 1.28 and 1.18 solar masses, respectively.
Zeta² Cancri.
Zeta Cancri Ca is the brightest of the three components, having an apparent magnitude of +6.12. It appears to be a yellow G-type star, often reported as G5V, but now thought to be earlier, probably G0V. This star has around 1.15 solar masses. The tenth magnitude Zeta Cancri Cb is a close pair of red dwarfs. The separation between Ca and Cb is approximately 0.3 arcseconds, and their orbital period is 17 years.


Chi Draconis

Chi Draconis (χ Dra, χ Draconis, Chi Draconis) is a star system in the constellation Draco.
Description.
The first companion is a yellow-white (class F) fourth-magnitude star with a mass approximately equal to that of the sun, but it is nearly twice as luminous. The second companion is an orange (class K) sixth-magnitude star, that is less massive and of lesser luminosity than the sun. In 1898 this system was reported to be a spectroscopic binary system, with an orbital period of 280.55 days. The two stars have an average separation of nearly an astronomical unit, which would disrupt the orbit of any Earth-like planet that was close enough to the primary to support liquid water. The two stars have less than half the abundance of heavy elements as the Sun and are approximately a billion years older. Separations between the two stars have been measured and the difference in brightness between the two stars is 2.12 magnitudes at 700 nm.


Tau4 Serpentis

Tau4 Serpentis, Latinized from τ4 Serpentis, is a M-type bright giant star in the constellation of Serpens, approximately 520 light-years from the Earth. It is classified as a semiregular late-type variable star, and its magnitude varies between +5.89 and +7.07 with a period of approximately 100 days. τ4 is unique among the stars with the Bayer designation τ Serpentis as being the only one with no HR catalog number.


HD 50235

HD 50235 is a class K5III (orange giant) star located approximately 811 light years away, in the constellation Puppis. Its apparent magnitude is 4.99. HD 50235 made its closest approach to the Sun 7.8 million years ago, at the distance of 137 light years, during which it had an apparent magnitude of 1.13.


HD 24040

HD 24040 is a metal-rich G-type star located approximately 152 light-years away in the constellation of Taurus. In 2006 a long-period planet was discovered.
Planetary system.
A long period planet was discovered in 2006 based on observations made at the W. M. Keck Observatory in Hawaii. However because the observations covered less than one complete orbit there were only weak constraints on the period and mass. The first reliable orbit for HD 24040b was obtained by astronomers at Haute-Provence Observatory in 2012 who combined the keck measurements with ones from the SOPHIE and ELODIE spectrographs. The most recent orbit published in 2015 added additional keck measurements and refined the orbital parameters.
A linear trend in the radial velocities indicating a possible additional companion was detected at Haute-Provence Observatory and was also detected at keck but at a much smaller amplitude.


HD 36678

HD 36678 is single star in the northern constellation of Auriga. This star is dimly visible to the naked eye with an apparent visual magnitude of 5.83. It is located at a distance of approximately 840 light years from the Sun based on parallax. This is an aging red giant star with a stellar classification of M0III. It is currently on the asymptotic giant branch of the HR diagram, and has expanded to ~63 times the radius of the Sun. The star is radiating ~875 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,950 K.
The brightness of HD 36678 is suspected of being variable. Hipparcos photometry showed maximum and minimum apparent magnitudes of 5.806 and 5.855 respectively, in the Hipparcos photometric band. No period was found, the variability has not been confirmed, and the star is not formally listed as a variable star.


WASP-43

WASP-43 is a K-type star in the Sextans constellation. It is about half the size of the Sun, and has approximately half the mass. WASP-43 has one known planet in orbit, a Hot Jupiter called WASP-43b. At the time of publishing of WASP-43b's discovery on April 15, 2011, the planet was the most closely orbiting Hot Jupiter discovered. The small orbit of WASP-43b is thought to be caused by WASP-43's unusually low mass. WASP-43 was first observed between January and May 2009 by the SuperWASP project, and was found to be cooler and slightly richer in metals than the Sun. WASP-43 has also been found to be an active star that rotates at a high velocity.
Observational history.
WASP-43 was first observed by the WASP-South part of the planet-searching SuperWASP project between January and May 2009. It was determined from the collected data that WASP-43 could potentially host a planet that transited, or crossed in front of, its host star as seen from Earth. Later observations by both the WASP-South and SuperWASP-North sections of SuperWASP between January and May 2010 yielded a total of 13,768 data points.
Scientists interpreted that a 0.81-day orbit of a possible planet from the data, and followed up with observations using the CORALIE spectrograph on the Leonhard Euler Telescope at Chile's La Silla Observatory. CORALIE provided radial velocity measurements that indicated that WASP-43 was being transited by a planet that was 1.8 times Jupiter's mass, now dubbed WASP-43b. Another follow-up using the TRAPPIST telescope further defined the light curve of the body transiting WASP-43.
WASP-43b's discovery was reported on April 15, 2011 in the journal "Astronomy and Astrophysics".
Characteristics.
WASP-43 is a K-type star with a mass that is 0.58 times that of the Sun, and a radius that is 0.93 times that of the Sun. In other words, WASP-43 is far less massive than the Sun, but is approximately the same size. With an effective temperature of 4400 K, WASP-43 is cooler than the Sun. It also has slightly lower quantities of iron than the Sun, with a measured metallicity of [Fe/H] = -0.05 (89% of that measured in the Sun). However, in general, the star has a slightly larger quantity of metals than the Sun. A notable exception is lithium, which is not present in WASP-43's spectrum. However, the star's spectrum also indicates that WASP-43 is an active star. WASP-43 has been found to rotate quickly, although the exact mechanism that causes such speed in this rotation is uncertain, it may be possible that this is caused by tidal interactions between WASP-43 and its planet.
With an apparent magnitude of 12.4, WASP-43 cannot be seen with the unaided eye. The star is located approximately 80 parsecs (260 light years) away from Earth.
Planetary system.
WASP-43b is a Hot Jupiter with a mass that is 1.78 times the mass of Jupiter and a radius that is 0.93 times Jupiter's radius. WASP-43b orbits its host star every 0.813475 days (19.5234 hours) at a distance of 0.0142 AU, the closest orbit yet found at the time of WASP-43b's discovery. WASP-43's unusually low mass accounts for WASP-43b's small orbit. Because planets with orbits around stars like WASP-43 are not usually observed, models either suggest that planets like WASP-43b are either uncommon or have short lifetimes caused by a decay in their orbits. WASP-43b has a density of 2.20 g/cm3


Delta Corvi

Delta Corvi (δ Corvi, abbreviated Delta Crv, δ Crv), also named Algorab , is a third magnitude star at a distance of from the Sun in the southern constellation of Corvus.
Nomenclature.
"δ Corvi" (Latinised to "Delta Corvi") is the star's Bayer designation.
It bore the traditional name "Algorab" derived from Arabic "الغراب" "al-ghuraab", meaning 'the crow'). 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 "Algorab" for this star.
In Chinese, (), meaning "Chariot (asterism)", refers to an asterism consisting of Delta Corvi, Gamma Corvi, Epsilon Corvi and Beta Corvi. Consequently, Delta Corvi itself is known as (, .).
Stellar properties.
Delta Corvi has more than 2.7 times the mass of the Sun, which is causing it to radiate a much higher energy output—roughly 69 times the Sun's luminosity. The effective temperature of the outer atmosphere is , giving it the white hue of an A-type star. The spectrum matches a stellar classification of . However it is more luminous—65-70 times that of the Sun—than it would be if it were on the main sequence. Hence it is either a subgiant star around 260 million years old that has nearly exhausted the supply of hydrogen at its core and is in the process of evolving away from the main sequence of stars like the Sun, or a pre main sequence star around 3.2 million years old that has not completely condensed and settled on the main sequence.
In 1823, Delta Corvi was found to be a wide double star by British astronomers James South and John Herschel. Since that time, the position of the two stars with respect to each other has not changed. The magnitude 9.3 companion, HR 4757 B, with a classification of K2Ve, is at an angular separation of 24.2 arcseconds along a position angle of 214°. Although the two stars share a common proper motion, the significant differences in their estimated ages suggests that they may not be physically connected.
A 2006 study found that Delta Corvi displayed no excess infrared emission that would otherwise suggest the presence of circumstellar matter, however warm interstellar dust was detected in a 2014 study.
In culture.
USS Algorab (AKA-8) is a United States navy ship named after the star.


Gamma Lupi

Gamma Lupi (γ Lupi, γ Lup) is a 3rd-magnitude, B-type blue giant star in the constellation of Lupus. It is also known in ancient Chinese astronomy as 騎官一 or "the 1st (star) of the Cavalry Officer". With a telescope, Gamma Lupi can be resolved into a binary star system in close orbit. This is known as the Gamma Lupi AB system, often abbreviated as γ Lupi AB or γ Lup AB. Gamma Lupi A is itself a spectroscopic binary with a period of 2.8081 days.
This star is a proper motion member of the Upper-Centaurus Lupus sub-group in the
Scorpius-Centaurus OB association,
the nearest such co-moving association of massive stars to the Sun.


CH Cygni

CH Cygni (CH Cyg / HIP 95413 / BD +49 2999) is a red giant, variable, symbiotic binary in the constellation Cygnus. It is the nearest symbiotic star to Earth, and one of the brightest, making it an ideal candidate for study.
Properties.
CH Cygni has a mass of and a radius of . Its white-dwarf companion has a mass of , and the orbital period of the two stars is 5689 days. CH Cygni is classified as M7IIIab + Be.
Observation history.
The earliest observations of CH Cygni were made in 1890 by Pickering and Wendel using wedge photometer, and was classified as a M6III variable star in 1924. In 1963 strong H I emissions were observed, indicating CH Cygni was likely in a symbiotic relationship with a white dwarf. Similar emissions were observed in 1965, 1967, 1977, 1992, and 1998. The system was briefly thought to contain a third star but this was later disproved.
In 1984 bipolar jets were detected coming from CH Cygni, which were suspected to be due to accretion from its companion star. The luminosity of the system decreased significantly in 1986, likely owing to dust thrown out of the system by the jets or a concurrent helium flash. This dust had dissipated by 2002, with subsequent luminosities returning to pre-1985 levels.


NGC 3925

NGC 3925 is a barred lenticular galaxy and a ring galaxy located about 370 million light-years away in the constellation Leo. It was discovered by astronomer Heinrich d'Arrest on February 19, 1863.
NGC 3925 is classified as a "PAS galaxy" because it contains mostly old stars, with no observable star formation activity. NGC 3925 is also a member of the Coma Supercluster.


V744 Centauri

V744 Centauri, is a semi-regular variable pulsating star in the constellation Centaurus. Located 3 degrees north north east of Epsilon Centauri, It ranges from apparent magnitude 5.1 to 6.7 over 90 days. It is unusual in that it is a red star with a high proper motion (greater than 50 milliarcseconds a year).


Epsilon Capricorni

Epsilon Capricorni, Latinized from ε Capricorni, is a quadruple star system in the constellation Capricornus. It has the traditional star name Castra or Kastra, meaning "fort" or "military camp" in Latin. Based upon an annual parallax shift of 3.09 mas as seen from the Earth, the star is located about 1,060 light years from the Sun. It can be seen with the naked eye, having a combined apparent visual magnitude of 4.62.
In Chinese, (), meaning "Line of Ramparts", refers to an asterism consisting of ε Capricorni, κ Capricorni, γ Capricorni, δ Capricorni, ι Aquarii, σ Aquarii, λ Aquarii, φ Aquarii, 27 Piscium, 29 Piscium, 33 Piscium and 30 Piscium. Consequently, the Chinese name for ε Capricorni itself is (, .)
The triple system comprises a close binary pair with an orbital period of 129 days, and a more distant, second companion star. The primary, component Aa, is a Be star that is surrounded by ionized gas that is producing the emission lines in the spectrum. This circumstellar shell is inclined by 80° to the line of sight from the Earth. The system is undergoing both short term and long term variations in luminosity, with the short period variations showing a phase cycle of 1.03 days. It is classified as a Gamma Cassiopeiae variable with an amplitude of 0.16 in magnitude.
Epsilon Capricorni Aa is a blue-white hued B-type main sequence star with a stellar classification of B2.5 Vpe and a visual magnitude of +4.62. It has 7.6 times the mass of the Sun and 4.8 times the Sun's radius. The star is spinning rapidly, with a projected rotational velocity of 225 km/s. This is giving it an oblate shape with an equatorial bulge that is 7% larger than the polar radius.
The system has two visual companions. Component B is a visual magnitude 10.11 star at an angular separation of 65.8 arc seconds along a position angle of 46°, as of 2013. Component C with visual magnitude of 14.1 lies at an angular separation of 62.7 arc seconds along a position angle of 164°, as of 1999.


Theta Canis Majoris

Theta Canis Majoris (θ Canis Majoris) is a solitary, orange-hued star near the northern edge of the constellation Canis Major, forming the nose of the "dog". The star is visible to the naked eye with an apparent visual magnitude of 4.08. Based upon an annual parallax shift of 12.51 mas as seen from Earth, it is located about 260 light years from the Sun. The star is moving away from us with a radial velocity of +96.2 km/s.
This is an old, evolved K-type giant star with a stellar classification of K4 III. It is about ten billion years old with 0.95 times the mass of the Sun, but has expanded to 32 times the Sun's radius. The star is radiating 263 times the Sun's luminosity from its photosphere at an effective temperature of 4,145 K.


HD 82205

HD 82205 is a double star in the southern constellation of Antlia. However, the primary is most likely a solitary star as the other component is deemed a line of sight companion. This is a giant star with a stellar classification of K3III.


NGC 5964

NGC 5964 is a barred spiral galaxy in the constellation Serpens Caput. NGC 5964 is also known by the names IC 4551 and PGC 55637.
NGC 5964 has relatively unwound spiral arms; it lacks the clear defined spiral arms the Milky Way galaxy has. The central bar is very small, long and thin. NGC 5964 thus does not have a galactic habitable zone like the Milky Way. For the Milky Way, the galactic habitable zone is commonly believed to be an annulus with an outer radius of about 10 kiloparsecs and an inner radius close to the Galactic Center, both of which lack hard boundaries.


List of stars in Ursa Minor

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


Nu2 Canis Majoris b

Nu2 Canis Majoris b, (7 CMa b) is a water cloud jovian extrasolar planet orbiting the star Nu2 Canis Majoris, approximately 64.71lys away in the constellation of Canis Major. The planet is thought to be inside the habitable zone with an orbit around its parent star of 1.9AU. It was discovered in 2011 by Wittenmyer, R. by radial velocity.


Mu Geminorum

Mu Geminorum (μ Geminorum, abbreviated Mu Gem, μ Gem), formally named Tejat , is a single star in the northern constellation of Gemini. From parallax measurements obtained during the Hipparcos mission, it is roughly distant from the Sun.
Mu Geminorum forms the primary or 'A' component of a double star system designated WDS J06230+2231 along with UCAC2 39641417 (also designated WDS J06230+2231BC), itself a binary pair.
Nomenclature.
"μ Geminorum" (Latinised to "Mu Geminorum") is the star's Bayer designation. WDS J06230+2231 is the double star's designation in the Washington Double Star Catalog. The designations of the double star's components as WDS J06230+2231A and BC derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Mu Geminorum bore the traditional name of "Tejat" (or more precisely, "Tejat Posterior"), from an old southern Arabic word of unknown meaning, "tiḥyāt". The name "Tejat Posterior" was formerly applied to an asterism consisting of this star, along with Gamma Geminorum (Alhena), Nu Geminorum, Eta Geminorum (Propus), and Xi Geminorum (Alzirr). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name "Tejat" for the component WDS J06230+2231A (i.e. Mu Geminorum) on February 1, 2017 and it is now so included in the List of IAU-approved Star Names.
The names "Calx" (Latin, meaning 'heel'), "Pish Pai" (from the Persian پیش‌پای ('pīshpāy', meaning 'foreleg'), and "Nuhatai" (from Arabic 'Al Nuḥātai', the dual form of 'Al Nuḥāt', 'a Camel's Hump') have also been applied to Mu Geminorum.
In Chinese, (), meaning "Well (asterism)", refers to an asterism consisting of Mu Geminorum, Gamma Geminorum, Nu Geminorum, Xi Geminorum, Epsilon Geminorum, 36 Geminorum, Zeta Geminorum and Lambda Geminorum. Consequently, Mu Geminorum itself is known as (, ).
Properties.
Mu Geminorum has an average apparent visual magnitude of 2.9, which makes it the fourth-brightest member of Gemini. It is 0.8 degrees south of the ecliptic, so it is subject to occultations by the Moon and, rarely, by planets. Seen from Earth, its brightness is reduced by 0.07 magnitudes by extinction from intervening gas and dust.
It is a slow irregular variable of type LB. Its brightness varies between magnitude +2.75 and +3.02 over a 72-day period, along with a 2,000-day period of long term variation. It is a red giant at a stellar classification of M3 III, with a surface temperature of 3,773 K, meaning it is brighter, yet cooler, than the Sun. The star is currently on the asymptotic giant branch and is generating energy through the nuclear fusion of hydrogen and helium along concentric shells surrounding an inert core of carbon and oxygen.


Rho Aurigae

Rho Aurigae (ρ Aur, ρ Aurigae) is the Bayer designation for a binary star system in the northern constellation of Auriga. It is faintly visible to the naked eye with an apparent visual magnitude of +5.22. Judging by parallax measurements, this system is approximately distant from the Earth, give or take a 30 light-year margin of error.
System.
ρ Aurigae is a single-lined spectroscopic binary system; the presence of a companion object is revealed by shifts in the stellar spectrum. The pair orbit each other with a period of 34.49 days and an orbital eccentricity of 0.10.
The primary component of this system is a B-type main sequence star defined as a standard star for the stellar classification of B5 V. The deduced mass of the secondary and the lack of evidence for it in the spectrum suggest it may be a B- or A-type star somewhat less luminous than the primary.
Name.
Rho Aurigae, along with λ Aur and μ Aur, were Kazwini's "Al Ḣibāʽ" (ألحباع), the Tent. According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "Al Ḣibāʽ" were the title for three stars : λ Aur as "Al Ḣibāʽ I", μ Aur as "Al Ḣibāʽ II" and σ Aur as "Al Ḣibāʽ III".
In Chinese, (), meaning "Pool of Harmony", refers to an asterism consisting of ρ Aurigae, λ Aurigae and HD 36041. Consequently, the Chinese name for ρ Aurigae itself is (, .)


List of stars in Scutum

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


FK Comae Berenices

FK Comae Berenices is a variable star that varies in apparent magnitude between 8.14 and 8.33 over a period of 2.4 days. It is the prototype for the FK Comae Berenices (FK Com) class of variable stars. The variability of FK Com stars may be caused by large, cool spots on the rotating surfaces of the stars. This star is thought to be the result of a recent binary merger, resulting in a high rate of both spin and magnetic activity.
The spectral class of FK Comae Berenices is G4 III, although it is considered unusual in having very broad absorption lines as well as some emission lines. The broadened spectral lines are due to rapid rotation.
The rotation rate of FK Comae Berenices is unusually fast for a cool giant star. It is speculated that this is due to the merger of a contact binary pair of stars into a single star. The rotation produces extremely strong magnetic fields which are expected to brake the star to a slower rotation rate. Analysis of variability due to star spots on the surface show that the star rotates at different speeds at different latitudes.
FK Comae Berenices is listed as a companion to the slightly brighter HD 117567. The two are not thought to be physically associated, with HD 117567 being a much closer F2 main sequence star.


NGC 4636

NGC 4636 is an elliptical galaxy located in the constellation Virgo. It is located at a distance of circa 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4636 is about 105,000 light years across. It was discovered by William Herschel on February 23, 1784. NGC 4636 lies one and a half degrees southwest of Delta Virginis. It can be viewed through a telescope at a ×23 magnification as a bright oval glow. It is part of the Herschel 400 Catalogue.
Characteristics.
The central part of NGC 4636 is circular and is surrounded by an elongated fainter envelope, containing a large number of globular clusters. The galaxy has an active galactic nucleus (AGN) that has been categorised as LINER or a type 1.9 Seyfert galaxy. The source of nuclear activity in galaxies is suggested to be a supermassive black hole that accretes material. NGC 4636 harbors a relatively small supermassive black hole with mass , as inferred from the bulge velocity dispersion.
Molecular gas.
When imaged in CO(2–1) there appear molecular clouds in NGC 4636. Cloud 1 is not associated with detectable optical emission and is out of the dust extinction map field of view, while cloud 2 is centered on a dust absorption knot and aligned with a ridge in the optical line emission map. The faint NGC 4636 ALMA continuum is in good agreement with the expected emission from cold dust, which would indicate that the dust content of NGC 4636 is fairly centrally located. The associated total molecular mass is .
The ultraviolet emission of NGC 4636 exhibits O vi emission, which is a tracer of gas cooling. The measured emission indicates a cooling rate of 0.3 M⊙ yr−1. Polycyclic aromatic hydrocarbons (PAH) emission was detected at 11.3 and 17 μm, as well as [Ne ii], [Ne iii], and [S iii] lines in the center of NGC 4636 (within re/8) using the Spitzer IRS. The far infrared emission of the galaxy, as observed by the Infrared Space Observatory is 50 times more than expected based on stellar emission alone. This strongly suggests that there is dust, probably accreted in a recent merger with a gas-rich galaxy. Hα observations reveal the presence of warm (T ~ 104 K) ionized gas in the inner kpc of NGC 4636. Spectra of this gas indicate irregular motion, with a typical velocity of 150–200 km/s. Hα maps of the galaxy core show the presence of a cavity in the distribution of the ionized gas encircled by a dense shell located at a distance of ~400 pc from the center. Again, the most plausible explanation is gas expansion caused by AGN activity.
In NGC 4636, the [C ii] emission extends to a radius of ~1 kpc and is centrally peaked. The velocities inferred from the [C ii] line are consistent with those measured for the Hα line. Finally, NGC 4636 has an excess of cold dust, approximately cospatial with the ionized and molecular gas. As above, this dust is expected be embedded in cold gas, to be protected against rapid sputtering. The extended dust distribution originates from the ejection of cold gas by AGN activity 10 Myr ago.
Globular clusters.
NGC 4636 is characterised by its large number of globular clusters, much larger than that of galaxies with similar size located not in the centre of galaxy clusters. The total number of globular clusters within a radius of 14 arcminutes is estimated to be 4,200 ± 120 and within 7 arcminutes is estimated to be 3,500 ± 170. In comparison, globular clusters orbit around Messier 87, the giant elliptical galaxy at the centre of the Virgo Cluster, and 150–200 lie in and around the Milky Way. The number of globular clusters drops abruptly at 7 and 9 arcminutes, probably indicating the edge of the galaxy.
The color distribution of the globular clusters in the galaxy is bimodal, a distribution that has been observed in other galaxies too. The globular clusters are characterised based on their color as blue or red. The population of red clusters is higher. Similarly with color, the metallicity distribution is bimodal, with two peaks at [Fe/H] = −1.23(σ = 0.32) and −0.35(σ = 0.19). The ages of the globular clusters in NGC 4636 vary from 2 to 15 billion years, with a bit more than a quarter of the clusters having ages less than 5 billion years. It has been suggested that the younger clusters were formed during the merging of smaller galaxies with the elliptical galaxy.
The velocity dispersion of the clusters is km/s, with the velocity dispersion of the blue clusters being slightly larger. This velocity dispersion is similar to that of Messier 60, which is, however, a brighter galaxy. Comparing the velocity dispersion of the globular clusters with the stellar one it is calculated that mass-to-light ratio is not constant, but should increase as the galactocentric distance increases, indicating the existence of an extended dark matter halo in NGC 4636.
X-ray emission.
NGC 4636 is one of the most luminous nearby elliptical galaxies when observed in X-rays, with estimated X-ray flux of erg/s. A hot gas corona around the galaxy was first detected by the Einstein Observatory. Based on the hot interstellar medium temperature profile, the total mass of the halo was estimated to be within a radius of 35 kpc. The percentage of non-luminous matter mass is estimated to be between 50% and 80% of the total galactic mass, implying an exceptionally low baryon fraction in NGC 4636 and the presence of a large dark matter halo.
The halo of NGC 4636 has some unique features. Observations by the Chandra X-ray Observatory revealed symmetric, 8 kpc long structures within the halo that look like spiral arms. The arms are about 30 percent hotter than the surrounding gas cloud. The arms form the rim of two large ellipsoid bubbles of hot gas. One more bubble-like feature has been detected about 2 kpc south of the northeastern arm. A weak radio source, elongated in the NE–SW direction, connects the NE and SW bubbles. These large bubbles are likely the result of shocks generated by the AGN jets. It is possible that the bubbles have different ages, generated by different AGN outbursts, as indicated by the presence of radio-emitting plasma in one cavity, while the others are radio-quiet.
NGC 4636 has an X-ray-bright core, having a radius of ~1 kpc. The core shows a central cavity surrounded by a bright edge. Interestingly, the small X-ray cavity surrounds the ~1 kpc radio jet detected at 1.4 GHz and is likely generated by the jet. Thus, the X-ray and radio observations point to a scenario in which gas may be currently outflowing in the central kpc of NGC 4636.
There are 318 point X-ray sources in the field of NGC 4636. About 25% of them are identified as background sources. 77 of the sources match the location of globular clusters. No correlation was found between the X-ray luminosities of the matched point sources and the luminosity or color of the host GC candidates. The other point sources are low-mass X-ray binaries.
Supernovae.
Two supernovae have been observed in NGC 4636, the first being SN 1939 A. It was a type Ia supernova whose maximum magnitude was estimated to be 11.9. It was discovered by Fritz Zwicky. In January 2020 another type Ia supernova, SN 2020ue, was discovered by Koichi Itagaki.
Nearby galaxies.
NGC 4636 is the foremost galaxy of the galaxy group known as the NGC 4636 group. Other members of the group include NGC 4457, NGC 4586, NGC 4587, NGC 4600, NGC 4665, and NGC 4688. These galaxies, along with NGC 4753, Messier 61 and their groups form the southern boundary of the Virgo cluster. It can be difficult to determine which galaxies belong to which group especially around the southern edge of the Virgo cluster where there is a confusion of galaxies at different distances. NGC 4636 has also been listed as a member of the Virgo Cluster.


Mu Sculptoris

μ Sculptoris, Latinized as Mu Sculptoris, is a solitary, orange-hued star in the southern constellation of Sculptor. It is visible to the naked eye as a dim point of light with an apparent visual magnitude of +5.30. This star is located approximately 291 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +16 km/s.
This object is an aging K-type giant star with a stellar classification of K1 III. Having exhausted the supply of hydrogen at its core, this star expanded and cooled off the main sequence. At present it has 11 times the girth of the Sun. It is a suspected variable star of unknown type, with its brightness measured as varying from magnitude 5.30 down to 5.33. The star has 1.32 times the mass of the Sun and is radiating 61 times the Sun's luminosity from its swollen photosphere at an effective temperature of 4899 K.


W Ursae Minoris

W Ursae Minoris is a multiple star system in the constellation Ursa Minor. Its apparent magnitude ranges from 8.51 to 9.59 over 1.7 days as one star passes in front of the other relative to observers on Earth. The combined spectrum of the system is A2V, but the masses of the two component stars are unknown. A slight change in the orbital period in 1973 suggests there is a third component of the multiple star system—most likely a red dwarf—with an orbital period of 62.2 ± 3.9 years.


Kepler-37

Kepler-37, also known as UGA-1785, is a G-type main-sequence star located in the constellation Lyra 209 light years from Earth. It is host to exoplanets Kepler-37b, Kepler-37c, Kepler-37d and Kepler-37e, all of which orbit very close to it. Kepler-37 has a mass about 80.3 percent of the Sun's and a radius about 77 percent as large. It has a temperature similar to that of the Sun, but a bit cooler at 5,417 K. It has about half the metallicity of our Sun. With an age of roughly 6 billion years, it is slightly older than the Sun, but is still a main-sequence star. Until January 2015, Kepler-37 was the smallest star to be measured via asteroseismology.
Planetary system.
Kepler-37b is the closest planet to the Kepler-37. At the time of its discovery in February 2013, it was the smallest known exoplanet. At in diameter, it is slightly larger than the Moon. It orbits Kepler-37 once every 13 days at a distance of about 0.1 astronomical units (AU). Kepler-37b has a rocky surface and is believed to be too small and too close to its star to support water or maintain an atmosphere. Surface temperature is estimated at .
Kepler-37c is around three-quarters of the diameter of Earth and orbits approximately every 21 days at a distance of just under 0.14 AU. Kepler-37d is about twice the diameter of Earth. It orbits in around 40 days at a distance of nearly 0.21 AU. Neither are able to support water due to their proximity to Kepler-37.
The periods of the three inner planets are close (within one per cent) to a 5:8:15 mean-motion resonance relationship.
In 2015, a grant was approved to further expand the Sagan Planet Walk by installing a Kepler-37d station on the Moon away.
Discovery.
The Kepler planets were discovered in September 2012 with the aid of transit events detected by the Kepler space telescope, and announced to the public in February 2013. Computer simulation was used to rule out other astronomical phenomenon mimicking planetary transit with probabilities of error <0.05% (3σ) for each potential planet. Additionally, simulation demonstrated that the proposed planetary configuration was stable. The exoplanets were considerably smaller than any previously detected, leading "Science World Reports" to state that "a major technological improvement for the telescope" had been achieved.
Thomas Barclay, an astrophysicist on the Kepler space telescope team, said the discovery was "really good news" in the search for hospitable planets, a prime objective of the project, because it demonstrated the telescope was capable of detecting Earth-sized planets. However, he does not anticipate finding many planets as small as Kepler-37b due to the very small amount of light such planets obscure. According to NASA scientist Jack Lissauer, the discovery of Kepler-37b "suggests such little planets are common, and more planetary wonders await as we continue to gather and analyze additional data." Astronomer John Johnson of Caltech university said the discovery would have been "unimaginable" a few years ago and that the telescope had revolutionized astronomers' picture of the universe.
The asteroseismology work was, in part, paid for by White Dwarf Research Corporation, a crowd funded non-profit organization.
In 2014, a fourth planet with orbital period of 51 days was confirmed through transit timing variations. Previously this signal was thought to be a false positive.


NGC 6756

NGC 6756 is a small open star cluster in the constellation Aquila, close to NGC 6755.


L Velorum

The Bayer designations l Velorum and L Velorum are distinct. Due to , both designations link here. For the star


RCW 36

RCW 36 (also designated Gum 20) is an emission nebula containing an open cluster in the constellation Vela. This H II region is part of a larger-scale star-forming complex known as the Vela Molecular Ridge (VMR), a collection of molecular clouds in the Milky Way that contain multiple sites of ongoing star-formation activity. The VMR is made up of several distinct clouds, and RCW 36 is embedded in the VMR Cloud C.
RCW 36 is one of the sites of massive-star formation closest to our Solar System, whose distance of approximately 700 parsecs (2300 light-years). The most massive stars in the star cluster are two stars with late-O or early-B spectral types, but the cluster also contains hundreds of lower-mass stars. This region is also home to objects with Herbig–Haro jets, HH 1042 and HH 1043.
Star formation in RCW 36.
Like most star-forming regions, the interstellar medium around RCW 36 contains both the gas from which stars form and some newly formed young stars. Here, young stellar clusters form in giant molecular clouds. Molecular clouds are the coldest, densest form of interstellar gas and are composed mostly of molecular hydrogen (H2), but also include more complex molecules, cosmic dust, and atomic helium. Stars form when the mass gas in part of a cloud becomes too great, causing it to collapse due to the Jeans instability. Most stars do not form alone, but in groups containing hundreds or thousands of other stars. RCW 36 is an example of this type of "clustered" star formation.
Molecular cloud and H II region.
The Vela Molecular Ridge can be subdivided into several smaller clouds, each of which in turn can be subdivided into cloud "clumps". The molecular cloud clump from which the RCW 36 stars are forming is Clump 6 in the VMR C cloud.
Early maps of the region were produced by radio telescopes that traced emission from several types of molecules found in the clouds, including CO, OH, and H2CO. More detailed CO maps were produced in the 1990s by a team of Japanese astronomers using the NANTEN millimeter-wavelength telescope. Using emission from C18O, they estimated the total mass of Cloud C to be 44,000 . The cloud maps suggest that Cloud C is the youngest component of the VMR because of an ultra-compact H II region associated with RCW 36 and several sites of embedded protostars, while H II regions in other VMR clouds are more evolved. Observations from the Herschel Space Telescope show that the material within the cloud is organized into filaments and RCW 36 sits near the south end of a 10-parsec long filament.
Star formation in RCW 36 is currently ongoing. In the dense gas at the western edge of RCW 36, where the far-infrared emission is greatest, are found protostellar cores, the Herbig Haro objects, and an ultra-compact H II region. However, more deeply embedded star-formation is obscured by dust, so radiation can only escape from the cloud surface and not from the embedded objects themselves.
The H II region is an area around the cluster in which hydrogen atoms in the interstellar medium have been ionized by ultraviolet light from O- and B-type stars. The H II region in RCW 36 has an hourglass morphology, similar to the shape of H II regions around other young stellar clusters like W40 or Sh2-106. In addition, an ultra-compact H II region surrounds IRAS source 08576−4333.
Star cluster.
Due to the youth of RCW 36, most of the stars in the cluster are at an early stage of stellar evolution where they are known as young stellar objects or pre-main-sequence stars. These stars are still in the process of contraction before they reach the main sequence, and they may still have gas accreting onto them from either a circumstellar disk or envelope.
Cluster members in RCW 36 have been identified through both infrared and X-ray observations. Bright infrared sources, attributed to massive stars, were first identified by the TIFR 100-cm balloon-born telescope from the National Balloon Facility in Hyderabad, India. In the early 2000s, infrared images in the J, H, and Ks bands have suggested at least 350 cluster members. Observations by NASA's Spitzer Space Telescope and Chandra X-ray Observatory were used to identify cluster members as part of the MYStIX survey of nearby star-forming regions. In the MYStIX catalog of 384 probable young stellar members of RCW 36, more than 300 of the stars are detected by X-ray sources. Modeling of the brightnesses of stars at various infrared wavelengths has shown 132 young stellar objects to have infrared excess consistent with circumstellar disks or envelopes.
The cluster has been noted by Baba et al. for having a high density of stars, with star counts (the number of stars within an angular area of the sky) exceeding 3000 stars per square parsec at the center of the cluster. A measurement of central area density using the MYStIX catalog suggested approximately 10,000 stars per square parsec at the cluster center, but this study also suggested that such densities are not unusual for massive star-forming regions. The spatial distribution of stars has been described as a King profile or alternatively as a "core-halo" structure.
Stellar density near the center of RCW 36 has been estimated to be approximately 300,000 stars per cubic parsec (or 10,000 stars per cubic light year). In contrast, the density of stars in the Solar neighborhood is only 0.14 star per cubic parsec, so the density of stars at the center of RCW 36 is about 2 million times greater. It has been calculated that for young stellar clusters with more than 104 stars pc.−3 close encounters between stars can lead to interactions between protoplanetary disks that affect developing planetary systems.
Young stellar objects.
Several special types of young stellar object have been identified in RCW 36, and are described in more detail below. The properties of these stars are related to their extreme youth.
Two stars in RCW 36 have Herbig-Haro jets (HH 1042 and HH 1043). Jets of gas flowing out from young stars can be produced by accretion onto a star. In RCW 36 these jets were seen in a number of spectral lines, including lines from hydrogen, helium, oxygen, nitrogen, sulfur, nickel, calcium, and iron. Mass loss rates from the jets have been estimated to be on the order of 10−7 solar masses per year. Inhomogeneities in the jets have been attributed to variable accretion rate on timescales of approximately 100 years.
The young star 2MASS J08592851-4346029 has been classified as a Herbig Ae star. Stars in this class are pre-main-sequence, intermediate-mass stars (spectral type A) with emission lines in their spectra from hydrogen. Observations indicate that 2MASS J08592851-4346029 has a bloated radius as would be expected for a young star that is still contracting. Some of the lines in its spectrum have a P-Cygni Profile indicating the presence of a stellar wind.
The young star CXOANC J085932.2−434602 was observed by the Chandra X-ray Observatory to have produced a large flare with a peak temperature greater than 100 million kelvins. Such "super hot" flares from young stars have been seen in other star-forming regions like the Orion Nebula.


Epsilon Piscis Austrini

Epsilon Piscis Austrini (ε Piscis Austrini) is a blue-white hued star in the southern constellation of Piscis Austrinus. It is visible to the naked eye with an apparent visual magnitude of +4.17. Based upon an annual parallax shift of 8.0981 ± 0.3582 mas as seen from the GAIA satellite, the system is located roughly 400 light years from the Sun.
This is a B-type main sequence star with a stellar classification of B8 Ve. It is a Be star that is spinning rapidly with a projected rotational velocity of 216 km/s, compared to an equatorial critical velocity of 301 km/s. The star has 4.1 times the mass of the Sun and is radiating 661 times the solar luminosity from its photosphere at an effective temperature of 11,066 K.
Epsilon Piscis Austrini is moving through the Galaxy at a speed of 18.7 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,900 and 28,100 light years from the center of the Galaxy.
Naming.
In Chinese, (), meaning "Palace Guard", refers to an asterism consisting of:
Consequently, the Chinese name for ε Piscis Austrini itself is (, .)


NGC 7025

 NGC 7025 is a spiral galaxy located about 210 million Light-years away from Earth in the constellation Delphinus. NGC 7025 is also classified as a LINER galaxy. The galaxy has an estimated diameter of 161,830 light-years. It was discovered by astronomer Albert Marth on September 17, 1863.
External links.


NGC 7259

NGC 7259 is a spiral galaxy approximately 66 million light-years away from Earth in the constellation of Piscis Austrinus. It was discovered by John Herschel on September 28, 1834.
Supernova SN 2009ip.
In 2009, a possible supernova was detected within the galaxy, and was designated SN 2009ip. Since the brightness faded in a matter of days, it was redesignated as Luminous blue variable (LBV) Supernova impostor.
During the following years several luminous outbursts were detected from the SN 2009ip. In September 2012 SN 2009ip was classified as a young type IIn supernova.


32 Orionis

32 Orionis is a triple star system in the equatorial constellation of Orion. It has the Bayer designation A Orionis, while "32 Orionis" is the Flamsteed designation This system is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.20. It is located approximately 303 light years away from the Sun based on parallax, and is drifting further away with a radial velocity of +18.6 km/s.
The system is a member of the eponymous 32 Orionis group, a young, nearby association of 46 co-moving stars first discovered in 2007.
The primary component of this system is a B-type main-sequence star with a stellar classification of B5V and a magnitude around 4.43. This is actually a spectroscopic binary with an orbital period of 3.964 days and eccentricity of 0.38. The unseen companion has an estimated mass of 0.6 times that of the Sun. Component B, at an angular separation of from the primary, is a class B7V star with a magnitude of 5.8, orbiting with the primary at a period of 614 years and eccentricity 0.22.


TZ Cassiopeiae

TZ Cassiopeaie (TZ Cas, HIP 117763, SAO 20912) is a variable star in the constellation Cassiopeia with an apparent magnitude of around +9 to +10. It is approximately 8,000 light-years away from Earth. The star is a red supergiant star with a spectral type of M3 and a temperature below .
TZ Cassiopeiae was reported as being variable by Williamina Fleming and published posthumously in 1911. It is a slow irregular variable star with a possible period of 3,100 days. It is over 60,000 times the luminosity of the Sun, and it is 645 times larger than the Sun. It is a member of the Cas OB5 stellar association, together with the nearby red supergiant PZ Cassiopeiae.
The initial mass of TZ Cassiopeiae has been estimated from its position relative to theoretical stellar evolutionary tracks to be around .
TZ Cas is losing mass through a powerful stellar wind at two millionths of a solar mass each year. It is unclear whether this is sufficient to cause the star to lose its atmosphere and become a blue supergiant before the core exhausts its fuel and collapses as a supernova. Either as a red or blue supergiant, or a Wolf–Rayet star, it will inevitably end its life violently in a supernova explosion when the core collapse occurs.


30 Ophiuchi

30 Ophiuchi is a single star in the equatorial constellation of Ophiuchus, and figures 0.99° east (specifically E½S) of the heart of cluster Messier 10. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.82. The distance to this star is approximately 350 light years based on parallax. Its present motion is, net, one of approaching rather than parting, at −6.7 km/s, its "radial velocity".
This is an aging giant star with a stellar classification of K4III, having exhausted the supply of hydrogen at its core and expanded to 36 times the Sun's radius. It is a suspected variable star. The star is radiating 300 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,009 K. It is emitting a far infrared excess due to circumstellar dust, which extends out to a diameter of and has a mass of .
The primary presents with two visual companions: B, at magnitude 9.71 and separation 99.8″, and C, at magnitude 8.75 and separation 220.9″ (3′ 40.9″).


Kepler-43

Kepler-43,formerly known as KOI-135, is a star in the northern constellation of Cygnus. It is located at the celestial coordinates: Right Ascension , Declination . With an apparent visual magnitude of 13.996, this star is too faint to be seen with the naked eye. The Kepler-43 has a very strong starspot activity.
Planetary system.
The Kepler spacecraft detected a transiting planet candidate around this star that was confirmed by radial velocity measurements taken by the SOPHIE spectrograph mounted on the 1.93 m telescope at the Haute-Provence Observatory.
The planet nightside temperature was measured to be 2043 K.


NGC 5238

NGC 5238 is an irregular galaxy in the constellation Canes Venatici. Located at a comoving distance of 4.51 Mpc, it is 64.4 arcseconds in diameter. It has sometimes been classified as a blue compact dwarf galaxy. Although some authors have hypothesized it to be a member of the M101 Group of galaxies, it is currently believed to be an isolated galaxy.
At an inclination of 39° with respect to Earth, NGC 5238 has a total mass of 117 million solar masses, with a star formation rate of 0.01 solar masses per year. Of the total mass, HI gas appears to account for 26 million solar masses.
Classification.
In 1977, NGC 5238 was hypothesized to not be a single galaxy, but rather a pair of interacting galaxies. It was not until ten years later that a dedicated study of the galaxy's rotation curve was undertaken, showing that the galaxy is indeed a single galaxy. One of the two regions that was thought to be the nucleus of a galaxy was instead shown to be simply a large HII region around 100 pc in diameter.
The morphological type of NGC 5238 has been the subject of some controversy. In 1979, the galaxy was classified as a barred spiral galaxy. Soon after, in 1984, the galaxy was included in a study of blue compact dwarf galaxies, incompatible with the classification of a barred spiral. However, the barred spiral classification was considered the correct classification for years. It was not until the mid 1990s that the galaxy was first recognized as a dwarf irregular galaxy. Even after this, the majority of studies recognized the galaxy as a spiral galaxy until 2015, when the classification of irregular finally became widely accepted
Appearance.
As it appears to us, NGC 5238 is tilted at an inclination of 39°. This 2013 estimate follows previous estimates of 30° in 1987, 37 ± 5° in 1992, and 47° in 1999 In the Spitzer 3.6 µm band, the semimajor axis of its angular size is 64.4", with an ellipticity of 0.201.
Distance.
The distance estimate to NGC 5238 has been brought down considerably since first calculated. The first published distance estimate was 7 Mpc, derived using redshift. This remained the predominant estimate until 1996, when the distance was found to be much less, estimated at 5.18 Mpc. Subsequently, using spectral data from the HI 21cm line, the distance was calculated to be 4.7 Mpc in 1999, although an updated HI study found a slightly higher value at 5.20 Mpc in 2002. Five years later, in 2007, the distance estimate was lowered even further to 4.50 Mpc, extremely close to today's accepted value.
One way to determine distance unambiguously is by standard candles. The tip of the red giant branch is such a method; every galaxy's brightest red giant stars must have exactly the same known luminosity. When combined with corrections for interstellar reddening, this allows for accurate determination of a galaxy's distance. By 2009, a Hubble Space Telescope image of NGC 5238 had become available, resolving the individual stars within the galaxy. Using this method, the distance modulus was calculated at 28.27 magnitudes, corresponding to a distance of 4.51 Mpc, today's accepted value.
Radio emission.
Since a first study was published in 1986, the neutral hydrogen gas of NGC 5238 and its associated 21 cm line have been the subject of many studies. The first study calculated the total HI 21 cm flux from the galaxy to be 4.5 ± 1.0 Jy·km/s, with a full width at half maximum of 28 km/s and a maximum flux density of 0.25 ± 0.011 Jy. Two years later, the 20% line width was calculated at two conflicting values from two studies: 47 km/s and 65 km/s. From the HI line data, the total mass to HI mass ratio was calculated to be 0.384 and the pseudo HI surface density was estimated to be 9.7 solar masses per square parsec. Another two years later, another estimate for the 20% and 50% line widths was published, calculating 36 ± 4 km/s at 50% and 49 ± 4 at 20%.
In 1999, the 50% line width was further refined to 32 ± 4 km/s, then 36 km/s. The second study, in addition to deriving the 5.20 Mpc distance quoted above, found a total HI mass of 4.2 solar masses. Finally, in 2013, the 50% line width estimate was further increased to 40 km/s, and the HI mass was refined to 2.6 solar masses, implying a total-to-HI mass ratio of 7.3.
In addition to HI gas, it is thought that radio continuum emission should be present from NGC 5238 as well. The galaxy is a strong ultraviolet emitter, indicating that the galaxy is undergoing rapid star formation. Based on this, it is to be expected that there should be radio continuum emission from the galaxy, due to the acceleration of electrons in HII regions, known as bremsstrahlung. However, such emission has not been found in NGC 5238, contradicting models. To resolve this mystery, it has been hypothesized that the star formation has subsided recently enough that the UV excess from massive stars is still present, but the hydrogen has already recombined.


NGC 274

NGC 274 is a lenticular galaxy in the constellation Cetus. It is a pair of galaxies, the other being NGC 275, which it is currently interacting with. It was discovered on September 10, 1785 by William Herschel. It is roughly 120 million light-years away.


NGC 6590

NGC 6590 is a reflection nebula in the constellation of Sagittarius. This nebula is near the similar reflection nebula NGC 6589. Both nebulas are flanked by red emission nebula IC 1284.


32 Tauri

32 Tauri is the Flamsteed designation for a solitary star in the zodiac constellation of Taurus. It has a visual magnitude of 5.64, making it visible to the naked eye from suburban skies (according to the Bortle scale). The position of this star near the ecliptic plane means that it is subject to occultations by the Moon. Parallax measurements put it at a distance of from the Sun. It is drifting further away with a radial velocity of +31.9 km/s, having come to within some 759,000 years ago.
The spectrum of this star matches a stellar classification of F2IV, with the luminosity class of IV indicating that this star has reached the subgiant stage and is in the process of evolving into a giant star. It has 47% more mass than the Sun with double the Sun's radius, but eight times the Sun's luminosity and about half the Sun's age. The abundance of elements other than hydrogen and helium is lower in this star compared to the Sun. The effective temperature of the star's outer atmosphere is 6,857 K, giving it the white-hued glow of an F-type star.


Iota Canis Majoris

Iota Canis Majoris (ι Canis Majoris, ι CMa) is a variable supergiant star in the constellation Canis Major.
Iota Canis Majoris is a blue-white B-type supergiant with an apparent magnitude that varies between +4.36 and +4.40. It has been classified as a Beta Cephei type variable star, but the supergiant spectral type and a period of over a month mean it is no longer considered to be of that type. It is approximately 3,100 light years from Earth. This star has 24.9 times the radius of the Sun.


F Eridani

The Bayer designation f Eridani (f Eri / f Eridani) is shared by two stars in the constellation Eridanus. They share a single Hipparcos catalogue entry, HIP 17797, but have separate Bright Star Catalogue listings, HR 1189 and 1190:


NGC 3054

NGC 3054 is an intermediate spiral galaxy in the constellation Hydra. It was discovered by Christian Heinrich Friedrich Peters in 1859. It is probably in the same galaxy group as NGC 2935.
In January 2006, the supernova SN 2006T was observed in NGC 3054.


HD 77370

HD 77370 is a single star in the constellation Carina. It has the Bayer designation b2 Carinae; "HD 77370" is the identifier from the "Henry Draper catalogue". This object has a yellow-white hue and is visible to the naked eye with an apparent visual magnitude of 5.17. It is located at a distance of 85 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +13 km/s.
This is an ordinary F-type main-sequence star with a stellar classification of F4V. It is around 1.3 billion years old and retains a relatively high projected rotational velocity of 60 km/s. The star has 1.45 times the mass of the Sun and 1.67 times the Sun's radius. It is radiating 4.8 times the luminosity of the Sun from its photosphere at an effective temperature of 6,699 K. The star is the most likely source of the X-ray emission detected at these coordinates.


Chi Geminorum

Chi Geminorum (χ Gem) is a binary star system in the constellation Gemini, near the western border with Cancer. It can be viewed with the naked eye on a dark night, having an apparent visual magnitude of 4.98. Based upon an annual parallax shift of 12.73 mas, it is located roughly 260 light years from the Sun.
The two components of this system form a spectroscopic binary with an orbital period of 2,437.8 days and an eccentricity of 0.06. The primary component is a K-type giant star with a stellar classification of K2 III. This is a candidate mild Barium star with the slight overabundance most likely acquired through accretion from what is now a white dwarf companion. The primary has an estimated 1.83 times the mass of the Sun and has expanded to 14 times the Sun's radius. The effective temperature of the outer atmosphere is 4,560 K, from whence it radiates 79 times the solar luminosity. It has a leisurely projected rotational velocity of 3.8 km/s and is around two billion years old.


22 Cygni

22 Cygni is a binary star system in the northern constellation of Cygnus. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 4.95. The annual shift of yields a distance estimate of around 1,070 light years. It is moving closer to the Earth with a heliocentric radial velocity of −15 km/s.
This is a single-lined spectroscopic binary with an orbital period of 78.2 days and an eccentricity of roughly 0.17. The visible component has a stellar classification of B5 IV that matches a B-type subgiant star. It is 37 million years old with a projected rotational velocity of 30 km/s and has an essentially solar metallicity, within the margin of error. The star has eight times the mass of the Sun and about 5.6 times the Sun's radius. It is radiating 7,305 times the Sun's luminosity from its photosphere at an effective temperature of 15,200 K.