Theta Serpentis

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Template:Starbox catalogue

θ Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Serpens
θ1 Ser
Right ascension Template:RA[1]
Declination Template:RA[1]
Apparent magnitude (V) +4.62[2]
θ2 Ser
Right ascension Template:RA[3]
Declination Template:DEC[3]
Apparent magnitude (V) +4.98[2]
Characteristics
θ1 Ser
Spectral type A5V[4]
θ2 Ser
Spectral type A5Vn[4]
Astrometry
θ1 Ser
Proper motion (μ) RA: +46.374 mas/yr[1]
Dec.: +31.313 mas/yr[1]
Parallax (π)24.2696±0.1753 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
θ2 Ser
Proper motion (μ) RA: +50.044 mas/yr[3]
Dec.: +28.363 mas/yr[3]
Parallax (π)24.5310±0.1083 mas[3]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Position (relative to A)
ComponentB
Epoch of observation2019
Angular distance22.40″ [5]
Position angle106° [5]
Projected separation900 AU [6]
Details
θ1 Ser
MassScript error: No such module "val".[7] Template:Solar mass
RadiusScript error: No such module "val".[7] Template:Solar radius
Luminosity24[8] Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val".[7] cgs
TemperatureScript error: No such module "val".[7] K
Rotational velocity (v sin i)130[9] km/s
Age594[10] Myr
θ2 Ser
MassScript error: No such module "val".[3] Template:Solar mass
RadiusScript error: No such module "val".[3] Template:Solar radius
LuminosityScript error: No such module "val".[3] Template:Solar luminosity
Surface gravity (log g)3.99[3] cgs
TemperatureScript error: No such module "val".[3] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Rotational velocity (v sin i)220[9] km/s
Age390[10] Myr
Database references
SIMBADθ Ser
θ1 Ser
θ3 Ser

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Theta Serpentis (θ Serpentis, abbreviated Theta Ser, θ Ser) is a binary star in the constellation of Serpens. It is visible to the naked eye with a combined apparent magnitude of 4.0.[11] Based on parallax measurements, it lies about 130 light-years distant.[1][3]

The two components are designated Theta Serpentis A, officially named Alya Script error: No such module "IPAc-en"., the traditional name for the entire system)[12][13] also called Theta1 Serpentis, and B, also called Theta2 Serpentis.

Nomenclature

θ Serpentis (Latinised to Theta Serpentis) is the system's Bayer designation; θ1 and θ2 Serpentis those of the brightest two components. The designations of the two constituents as Theta Serpentis AB and C, and those of AB's components - Theta Serpentis A and B - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[14]

The system bore the traditional name Alya, or Alga, from the Arabic الية ’alyah "fat tail (of a sheep)".[15] In 2016, the IAU organized a Working Group on Star Names (WGSN)[16] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[17] It approved the name Alya for the component Theta Serpentis A on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[13]

In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Dzaneb al Haiyet, which was translated into Latin as Cauda Serpentis, meaning 'the serpent's tail'.[18]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Left Wall of Heavenly Market Enclosure, refers to an asterism which represents eleven old states in China, consisting of Theta Serpentis, Delta Herculis, Lambda Herculis, Mu Herculis, Omicron Herculis, 112 Herculis, Zeta Aquilae, Eta Serpentis, Nu Ophiuchi, Xi Serpentis and Eta Ophiuchi.[19] Consequently, the Chinese name for Theta Serpentis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx), representing the state Xu (徐).[20][21]

Properties

Both Theta1 Serpentis and Theta2 Serpentis are A-type main sequence stars.[4] As of 2019Script error: No such module "Check for unknown parameters"., these two stars are 22 arcseconds apart on the sky along a position angle of 106°, values that changed little since the first observations in 1755.[5] At the system's distance, the angular separation give a projected separation of 900 astronomical units, implying an orbital period in the order of 10,000 years.[6] θ1 has an apparent magnitude of +4.62 while the slightly dimmer θ2 has a magnitude of +4.98.[2] Both stars are similar to each other in all respects, having luminosities of 24[8] and 13 times solar,[3] masses of 2.0 and 1.8 solar masses, radii of about twice solar and effective temperatures of Script error: No such module "val". and Script error: No such module "val"., respectively.[7][3]

The magnitude 6.71[22] star HD 175726[23] (Theta Serpentis C) is an optical companion to the pair. As of 2007Script error: No such module "Check for unknown parameters"., it is separated by 421" from A and 405" from B.[5] It is not gravitationally bound to the pair since its distance to Earth is 87 light-years, much closer than the AB pair. Its proper motion is also discrepant with that of Theta Serpentis.[24] It is a G-type main-sequence star[25] with about the same mass and radius as the Sun.[26]

References

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  1. ↑ a b c d e Template:Cite DR3
  2. ↑ a b c Script error: No such module "Citation/CS1".
  3. ↑ a b c d e f g h i j k l Template:Cite DR3
  4. ↑ a b c Script error: No such module "Citation/CS1".
  5. ↑ a b c d Script error: No such module "Citation/CS1".
  6. ↑ a b Script error: No such module "citation/CS1".
  7. ↑ a b c d e Script error: No such module "Citation/CS1". Theta2 Serpentis' database entry at VizieR.
  8. ↑ a b Script error: No such module "Citation/CS1".
  9. ↑ a b Script error: No such module "Citation/CS1".
  10. ↑ a b Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ a b 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. ↑ 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 Script error: No such module "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 Script error: No such module "webarchive"., Hong Kong Space Museum. Accessed on line November 23, 2010.
  22. ↑ Script error: No such module "citation/CS1".
  23. ↑ Template:Cite simbad
  24. ↑ Template:Cite DR3
  25. ↑ Script error: No such module "Citation/CS1".
  26. ↑ Script error: No such module "Citation/CS1". See Table 3.

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External links

Template:Stars of Serpens

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