Eta Draconis

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Template:Short description

η Draconis
Template:Location mark
Location of η Draconis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Draco
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) +2.73[2]
Characteristics
Spectral type G8 III[2]
U−B Template:Engvar +0.70[3]
B−V Template:Engvar +0.91[3]
Astrometry
Radial velocity (Rv)–14.3[4] km/s
Proper motion (μ) RA: –17.02[1] mas/yr
Dec.: +56.95[1] mas/yr
Parallax (π)35.42±0.09 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+0.58[5]
Details
A
MassScript error: No such module "val".[6] Template:Solar mass
Radius10.46[7]–10.53[8] Template:Solar radius
LuminosityScript error: No such module "val".[8] Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val".[6] cgs
Temperature5,018[7] K
Metallicity [Fe/H]–0.088[7] dex
Rotational velocity (v sin i)8[9] km/s
AgeScript error: No such module "val".[8] Myr
B
Mass0.672[10] Template:Solar mass
Radius0.577[10] Template:Solar radius
Luminosity0.206[10] Template:Solar luminosity
Temperature5,114[10] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Aldibain, Athebyne, 14 Draconis, BD+61 1591, FK5 822, HD 148387, HIP 80331, HR 6132, NSV 7713, SAO 17074, WDS 16240+6131.[11]
Database references
SIMBADdata

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Eta Draconis (η Draconis, abbreviated Eta Dra, η Dra) is a binary star in the northern circumpolar constellation of Draco. Despite having an apparent visual magnitude of only +2.73,[2] it is the second-brightest star in this generally faint constellation. Based upon parallax measurements collected during the Hipparcos mission, this star is located at a distance of about Script error: No such module "convert". from the Sun.[1]

The two components are designated Eta Draconis A (also named Athebyne Template:IPAc-en[12]) and B.

Nomenclature

η Draconis (Latinised to Eta Draconis) is the system's Bayer designation. The designations of the two components as Eta Draconis A and B derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[13]

Eta Draconis, together with Zeta Draconis, bore the traditional Arabic name الذئبين al-dhiʼbayn, "the (two) wolves", lying in wait for the camel's foal, the little star Al Rubaʽ, protected by the Mother Camels.[14]

In 2016, the IAU organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[16] It approved the name Athebyne (a rendering of adh-dhiʼbayn) for the component Eta Draconis A on 5 September 2017. It approved the name Aldhibah (the female wolf) for Zeta Draconis A on the same date. Both are now so included in the List of IAU-approved Star Names.[12]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Left Wall of Purple Forbidden Enclosure, refers to an asterism consisting of Eta Draconis, Iota Draconis, Theta Draconis, Zeta Draconis, Upsilon Draconis, 73 Draconis, Gamma Cephei and 23 Cassiopeiae.[17] Consequently, the Chinese name for Eta Draconis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx),[18] representing Script error: No such module "Lang". (Script error: No such module "Lang".), meaning The Second Premier.[19] Possibly, 少宰 (Shàozǎi) is westernized into Hea Tsae by R.H. Allen with meaning "the Lowest Steward" but it was for Theta Draconis.[20]

Properties

Eta Draconis A is a star with 2.88[7] times the mass of the Sun. The spectrum matches a stellar classification of G8 III,[2] with the luminosity class III indicating this is an evolved giant star that has exhausted the supply of hydrogen at its core. It reached this stage in only 650[8] million years because higher mass stars such as this consume the supply of hydrogen more rapidly than the Sun. The radius of Eta Draconis, as determined by its angular diameter and distance from Earth, is about 10.5 times the radius of the Sun.[7][8] From its extended envelope, it is radiating around 65[8] times the luminosity of the Sun at an effective temperature of 5,018 K,[7] giving it the yellow glow of a G-type star.[21]

Eta Draconis B is located at an angular separation of 5.1 arcseconds from the primary. This is an 8.8 magnitude K-type main sequence star with a stellar classification of K2 V.[22] At the estimated distance of this star system, the two stars are separated by a physical distance of at least 140 AU and require at least a millennium to complete an orbit.[23]

References

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  1. ↑ a b c d e f Script error: No such module "Citation/CS1".
  2. ↑ a b c d Script error: No such module "Citation/CS1".
  3. ↑ a b 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 c d e f Script error: No such module "Citation/CS1".
  8. ↑ a b c d e f Script error: No such module "Citation/CS1"..
  9. ↑ Script error: No such module "Citation/CS1".
  10. ↑ a b c d Script error: No such module "Citation/CS1".
  11. ↑ Template:Cite simbad
  12. ↑ a b Script error: No such module "citation/CS1".
  13. ↑ Script error: No such module "citation/CS1".
  14. ↑ Star Name - R.H Allen p. 202
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ 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.
  18. ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 10 日 Template:Webarchive
  19. ↑ 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.
  20. ↑ Star Name - R.H. Allen p. 210
  21. ↑ Script error: No such module "citation/CS1".
  22. ↑ Script error: No such module "Citation/CS1".
  23. ↑ Script error: No such module "citation/CS1".

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Template:Stars of Draco

Template:Authority control

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