Alpha Serpentis

Coordinates: Sky map 15h 44m 16.07431s, +06° 25′ 32.2633″
Source: Wikipedia, the free encyclopedia.
α Serpentis
Location of α Serpentis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension 15h 44m 16.07431s[1]
Declination +06° 25′ 32.2633″[1]
Apparent magnitude (V) 2.623[2]
Characteristics
Spectral type K2 IIIb CN1[3]
U−B color index +1.248[2]
B−V color index +1.167[2]
Distance
74.0 ± 0.3 ly
(22.68 ± 0.10 pc)
Absolute magnitude (MV)+0.88±0.03[5]
Details
Rotational velocity (v sin i)
4.3[8] km/s
HR 5854, SAO 121157, ADS 9765, CCDM 15442+0626[9]
Database references
SIMBADdata

Alpha Serpentis or α Serpentis, formally named Unukalhai (

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 74 light-years (23 parsecs) from the Sun
.

Properties

Alpha Serpentis is a giant star with a stellar classification of K2IIIbCN1,[3] having consumed the hydrogen at its core and evolved away from the main sequence. It has 1.7 times the mass and 13.5 times the radius of the Sun.[6] The effective temperature of the outer envelope is 4,498 K,[8] giving it an orange hue that is characteristic of a K-type star.[12] It has been classified as a strong CN star, showing a higher than expected strength in the cyanogen bands.[13]

This star is radiating about 38 times the

arcminutes
distant.

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)[14] 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.[11]

Alpha Serpentis is a member of the indigenous Arabic asterism al-Nasaq al-Yamānī "the Southern Line" of al-Nasaqān "the Two Lines",[15] along with Delta Serpentis, Epsilon Serpentis, Delta Ophiuchi, Epsilon Ophiuchi, Zeta Ophiuchi and Gamma Ophiuchi.[16] 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.[17]

In

Chinese name for Alpha Serpentis itself is 天市右垣七 (Tiān Shì Yòu Yuán qī, English: the Seventh Star of Right Wall of Heavenly Market Enclosure), and represents the state Shu (蜀) (or Shuh)[19][20] (together with Lambda Serpentis in R.H.Allen's works).[16]

References

  1. ^
    S2CID 18759600
  2. ^
    Bibcode:1966PDAUC...1....1G
  3. ^
    doi:10.1086/191373
    .
  4. S2CID 17804304
  5. S2CID 2756572
  6. ^
    S2CID 203078143
    . 148.
  7. ^
    University of Illinois
    , retrieved 2012-01-11
  8. ^
    S2CID 121883397
  9. Centre de Données astronomiques de Strasbourg
    , retrieved 2012-01-11
  10. ISBN 978-1-931559-44-7
    .
  11. ^ a b "IAU Catalog of Star Names". Retrieved 28 July 2016.
  12. Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original
    on February 22, 2012, retrieved 2012-01-16
  13. doi:10.1086/132025
    .
  14. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  15. ISBN 1-931559-44-9
  16. ^
    ISBN 0-486-21079-0
    , retrieved 2010-12-12
  17. ^ 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
  18. ISBN 978-986-7332-25-7
    .
  19. ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2010-08-19 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  20. ^ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived 2008-09-24 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
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