Alpha Serpentis

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Template:Short description Template:Sky

α Serpentis
Template:Location mark
Location of α Serpentis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 2.623[2]
Characteristics
Evolutionary stage Horizontal branch[3]
Spectral type K2 IIIb CN1[4]
U−B Template:Engvar +1.248[2]
B−V Template:Engvar +1.167[2]
Astrometry
Radial velocity (Rv)+2.63[5] km/s
Proper motion (μ) RA: +133.84[1] mas/yr
Dec.: +44.81[1] mas/yr
Parallax (π)44.10±0.19 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)Template:Val[6]
Details
MassTemplate:Val[7] Template:Solar mass
Radius12.19[8] Template:Solar radius
LuminosityTemplate:Val[7] Template:Solar luminosity
Surface gravity (log g)2.4[8] cgs
TemperatureTemplate:Val[7] K
Metallicity [Fe/H]0.189[8] dex
Rotational velocity (v sin i)4.3[9] km/s
AgeTemplate:Val[7] Gyr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[10]
Database references
SIMBADdata

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Alpha Serpentis or α Serpentis, formally named Unukalhai (Template:IPAc-en),[11][12] is a star in the head (Serpens Caput) of the equatorial constellation of Serpens. With an apparent visual magnitude of 2.6,[2] this star is the brightest in the constellation and it can be viewed with the naked eye from most of the Earth. Parallax measurements yield an estimated distance of about Template:Convert from the Sun.

Properties

Alpha Serpentis is a giant star with a stellar classification of K2IIIbCN1,[4] having consumed the hydrogen at its core and evolved away from the main sequence. It has 1.6 times the mass[7] and 13.5 times the radius of the Sun.[8] It is most likely a horizontal branch or red clump star, fusing helium into carbon and heavier elements within its core.[3] The effective temperature of the outer envelope is 4,687 K,[7] giving it an orange hue that is characteristic of a K-type star.[13] It has been classified as a strong CN star, showing a higher than expected strength in the cyanogen bands.[14]

This star is radiating about 30 times the luminosity of the Sun, while a further 32 times the Sun's luminosity is being emitted in the infrared, for 70-fold total.[3]

Nomenclature

α Serpentis (Latinised to Alpha Serpentis) is the system's Bayer designation.

It bore the traditional names Unukalhai (alternatively spelt Unuk al Hay or Unuk Elhaija) from the Arabic عنق الحيّة ʽunuq al-ḥayyah "the serpent's neck", and Cor Serpentis from the Latin "the Heart of the Serpent". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalogue and standardize proper names for stars. The WGSN approved the name Unukalhai for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.[12]

Alpha Serpentis is a member of the indigenous Arabic asterism al-Nasaq al-Yamānī "the Southern Line" of al-Nasaqān "the Two Lines",[16] along with Delta Serpentis, Epsilon Serpentis, Delta Ophiuchi, Epsilon Ophiuchi, Zeta Ophiuchi and Gamma Ophiuchi.[17] According to a 1971 NASA catalogue, al-Nasaq al-Yamānī or Nasak Yamani was the name for two stars: Delta Serpentis as Nasak Yamani I and Epsilon Serpentis as Nasak Yamani II.[18]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Right Wall of Heavenly Market Enclosure, refers to an asterism which represents eleven old states in China and which is marking the right borderline of the enclosure, consisting of Alpha Serpentis, Beta Herculis, Gamma Herculis, Kappa Herculis, Gamma Serpentis, Beta Serpentis, Delta Serpentis, Epsilon Serpentis, Delta Ophiuchi, Epsilon Ophiuchi and Zeta Ophiuchi.[19] Consequently, the Chinese name for Alpha Serpentis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx), and represents the state Shu (蜀) (or Shuh)[20][21] (together with Lambda Serpentis in R.H.Allen's works).[17]

References

Template:Reflist

Template:Stars of Serpens

  1. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named aaa474_2_653
  2. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named sps1966
  3. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named kaler
  4. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Keenan_McNeil_1989
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aaa430_165
  6. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aj135_3_892
  7. ↑ a b c d e f Cite error: Invalid <ref> tag; no text was provided for refs named baines2018
  8. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named Gray_Kaur_2019
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aj135_1_209
  10. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ a b Script error: No such module "citation/CS1".
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named csiro
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Keenan1987
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named kunitzsch_smart2006
  17. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named allen1963
  18. ↑ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
  19. ↑ 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.
  20. ↑ 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.
  21. ↑ Template:In lang English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.
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