Coordinates: Sky map 16h 25m 24.953s, +14° 01′ 59.77″

Omega Herculis

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This article is about ω Herculis; it is not to be confused with w Herculis.
ω Herculis
Location of ω Herculis (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hercules[1]
Right ascension 16h 25m 24.95425s[2]
Declination +14° 01′ 59.7711″[2]
Apparent magnitude (V) 4.5821[2] (4.58 + 11.5)[3]
Characteristics
Spectral type A2 Vp CrSr[4]
U−B color index +0.01[5]
B−V color index +0.00[5]
Variable type α2 CVn[6]
Astrometry
Radial velocity (Rv)−5.90±0.74[7] km/s
Proper motion (μ) RA: +40.86[2] mas/yr
Dec.: −59.71[2] mas/yr
Parallax (π)13.04±0.64 mas[2]
Distance250 ± 10 ly
(77 ± 4 pc)
Absolute magnitude (MV)0.29±0.15[8]
Details
ω Her A
Mass2.14[9] M☉
Radius3.30[10] R☉
Luminosity70[11] L☉
Surface gravity (log g)3.51±0.35[12] cgs
Temperature10,052±320[12] K
Metallicity [Fe/H]+0.47±0.15[12] dex
Rotation2.951[13] d
Rotational velocity (v sin i)55[14] km/s
Age149[9] Myr
Other designations
Cujam, ω Her, 24 Her, 51 Ser, BD+14°3049, FK5 613, HD 148112, HIP 80463, HR 6117, SAO 102153, WDS J16254+1402AB[15]
Database references
SIMBADdata

Omega Herculis (ω Herculis, abbreviated Omega Her, ω Her) is a binary star[3] system in the northern constellation of Hercules. Based upon an annual parallax shift of 13.04 mas as seen from Earth, it is located around 250 light-years from the Sun. It is faintly visible to the naked eye, having a combined apparent visual magnitude of 4.58.[2] The system is a candidate for membership in the Ursa Major Moving Group, although this remains uncertain.[8]

The two components are designated Omega Herculis A (officially named Cujam /ˈkjuːdʒəm/, the traditional name of the system)[16] and B.

Nomenclature

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ω Herculis (Latinised to Omega Herculis) is the system's Bayer designation. It previously bore the Flamsteed designation of 51 Serpentis before being added to Hercules.[17] The designations of the two components as Omega Herculis 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).[18]

The system bore the traditional name Cujam (also written as Cajam and Kajam), meaning ("club").[19] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[20][21] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[22] It approved the name Cujam for the component Omega Herculis A on February 1, 2017 and it is now so included in the List of IAU-approved Star Names.[16]

In Chinese, 斗 (Dǒu), meaning Dipper for Liquid, refers to an asterism consisting of Omega Herculis, 49 Serpentis, 13 Herculis, 29 Herculis and 33 Herculis.[23] Consequently, the Chinese name for Omega Herculis itself is 斗一 (Dǒu yī, English: the First Star of Dipper for Liquid).[24]

Properties

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The primary, Omega Herculis A, is a chemically peculiar Ap star with a stellar classification of A2 Vp CrSr.[4] The spectrum displays abnormally strong absorption lines of chromium and strontium, and weak lines of calcium and magnesium.[4] An A-type star, it has an estimated 2.14[9] times the mass of the Sun and 3.30[10] times the Sun's radius. The star is around 149[9] million years old and is radiating 70[11] times the solar luminosity from its photosphere at an effective temperature of 10,052 K.[12]

This component is an Alpha2 Canum Venaticorum variable[6] with a brightness amplitude of 0.4 magnitude and a 2.951 day phase that presumably matches the rotation period. The pattern of variation shows that there are regions of the star's surface where the concentrations of elements differ. The star also displays short period variations on the order of 2.5 hours.[13] It has a mean effective magnetic field value of 209×10−4 T.[25]

The secondary, Omega Herculis B, is a magnitude 11.5 companion star.[3] As of 2010, it was located at an angular separation of 0.80 arc seconds along a position angle of 294°.[26]

References

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  1. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Constellation record for this object at VizieR.
  2. ^ a b c d e f g Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  3. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  4. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  5. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  6. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  7. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  8. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  9. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  10. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  11. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  12. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  13. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  14. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  15. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  16. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  17. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  18. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  19. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  20. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  21. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  22. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  23. ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value)..
  24. ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2009-09-29 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  25. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  26. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).


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