Gamma Geminorum

From Wikipedia, the free encyclopedia
(Redirected from Almeisan)
Jump to navigation Jump to search

Template:Short description Script error: No such module "redirect hatnote".

γ Geminorum
Template:Location mark
Location of γ Geminorum (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Gemini
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 1.915[2]
Characteristics
Spectral type A1IV + G[3]
U−B Template:Engvar +0.137[2]
B−V Template:Engvar +0.005[2]
Astrometry
Radial velocity (Rv)−12.5[4] km/s
Proper motion (μ) RA: +13.81[1] mas/yr
Dec.: −54.96[1] mas/yr
Parallax (π)29.84±2.23 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−0.68[5]
Orbit[6]
Period (P)4,614.51 days
Eccentricity (e)0.8933 ± 0.0013
Periastron epoch (T)244399.13 ± 0.77
Argument of periastron (ω)
(secondary)		312.60 ± 0.60°
Semi-amplitude (K1)
(primary)		11.881 ± 0.068 km/s
Details
γ Gem A
Mass2.81[7] Template:Solar mass
RadiusScript error: No such module "val".[8] Template:Solar radius
LuminosityScript error: No such module "val".[9] Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val".[8] cgs
TemperatureScript error: No such module "val".[8] K
Metallicity [Fe/H]–0.12[10] dex
Rotational velocity (v sin i)Script error: No such module "val".[11] km/s
γ Gem B
Mass1.07[3] Template:Solar mass
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Alhena, 24 Geminorum, BD+16°1223, FK5 251, GCTP1539.00, HIP 31681, HD 47105, HR 2421, SAO 95912[1][12]
Database references
SIMBADdata

Script error: No such module "Check for unknown parameters".

Gamma Geminorum (γ Geminorum, abbreviated Gamma Gem, γ Gem), formally named Alhena Template:IPAc-en,[13] is the third-brightest object in the constellation of Gemini. It has an apparent visual magnitude of 1.9,[2] making it easily visible to the naked eye even in urban regions. Based upon parallax measurements with the Hipparcos satellite, it is located at a distance of roughly Script error: No such module "convert"..[1]

Properties

Alhena is an evolving star that is exhausting the supply of hydrogen at its core and has entered the subgiant stage. The spectrum matches a stellar classification of A0 IV.[14] Compared to the Sun it has 2.8[7] times the mass and five[8] times the radius. It is radiating around 200[9] times the luminosity of the Sun from its outer envelope at an effective temperature of 9,190 K.[8] This gives it a white hue typical of an A-class star.[15]

Alhena is a spectroscopic binary system with a period of 12.6 years (4,614.51 days) in a highly eccentric Keplerian orbit.[6] The secondary, with 1.07 times the mass of the Sun, is likely a G-type main-sequence star.[3]

Etymology

γ Geminorum (Latinised to Gamma Geminorum) is the star's Bayer designation. The traditional name Alhena is derived from the Arabic الهنعة Al Han'ah, 'the brand' (on the neck of the camel), whilst the alternate name Almeisan is from the Arabic المیسان Al Maisan, 'the shining one.' Al Hanʽah was the name of star association consisting of this star, along with Mu Geminorum (Tejat Posterior), Nu Geminorum, Eta Geminorum (Tejat Prior) and Xi Geminorum (Alzirr). They also were associated in Al Nuḥātai, the dual form of Al Nuḥāt, 'a Camel's Hump'.[16] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[17] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[18] included a table of the first two batches of names approved by the WGSN; which included Alhena for this star.

In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Nir al Henat, which was translated into Latin as Prima του al Henat, meaning 'the brightest of Al Henat'.[19]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Well (asterism), refers to an asterism consisting of γ Geminorum, ε Geminorum, ζ Geminorum, λ Geminorum, μ Geminorum, ν Geminorum, ξ Geminorum and 36 Geminorum.[20] Consequently, γ Geminorum itself is known as Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[21]

Conjunctions

Gamma Geminorum is 6° south of the ecliptic, far enough so that the Moon never occults it. Similarly, planets in conjunction with this star almost always pass several degrees to the north, but Venus will have a series of close conjunctions with Gamma Geminorum starting in August 2143, and continuing every eight years after over the remainder of that century.[22]

The Sun passes Gamma Geminorum on or around June 30 every year.[22]

In culture

Alhena was the name of a Dutch ship that rescued many people from an Italian cruise liner, the SS Principessa Mafalda, in October 1927.[23] In addition, the American attack cargo ship Script error: No such module "WPSHIPS utilities". was named after the star.

References

<templatestyles src="Reflist/styles.css" />

  1. ↑ a b c d e f g Script error: No such module "citation/CS1".
  2. ↑ a b c d Script error: No such module "citation/CS1".
  3. ↑ a b c Script error: No such module "citation/CS1".
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ Script error: No such module "citation/CS1".
  6. ↑ a b Script error: No such module "citation/CS1".
  7. ↑ a b Script error: No such module "citation/CS1".
  8. ↑ a b c d e Script error: No such module "citation/CS1".
  9. ↑ a b Script error: No such module "citation/CS1".
  10. ↑ Script error: No such module "citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Script error: No such module "citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "citation/CS1".
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ Script error: No such module "citation/CS1".
  20. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  21. ↑ Template:In lang 香港太空館 – 研究資源 – 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.
  22. ↑ a b Script error: No such module "citation/CS1".
  23. ↑ Script error: No such module "citation/CS1".

Script error: No such module "Check for unknown parameters".

Template:Stars of Gemini

Retrieved from "http://debianws.lexgopc.com/wiki143/index.php?title=Gamma_Geminorum&oldid=6172362"