Gamma Herculis
Template:Location mark Location of γ Herculis (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hercules |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | +3.75[2] |
| Characteristics | |
| Spectral type | A9 IIIbn[3] |
| U−B Template:Engvar | +0.18[2] |
| B−V Template:Engvar | +0.27[2] |
| Variable type | SRd?[4] |
| Astrometry | |
| Radial velocity (Rv) | –35.3[5] km/s |
| Proper motion (μ) | RA: –47.39[1] mas/yr Dec.: +43.81[1] mas/yr |
| Parallax (π) | 16.93±0.22 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | −0.12[6] |
| Details | |
| Radius | 6[7] Template:Solar radius |
| Luminosity | 92[6] Template:Solar luminosity |
| Surface gravity (log g) | 3.3[8] cgs |
| Temperature | 7,031[8] K |
| Metallicity [Fe/H] | +0.07[6] dex |
| Rotational velocity (v sin i) | 135[9] km/s |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| γ Her, 20 Herculis, BD+19°3086, HD 147547, HIP 80170, HR 6095, SAO 102107[10] | |
| Database references | |
| SIMBAD | data |
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Gamma Herculis, Latinized from γ Herculis, is a magnitude 3.74 binary star system in the northern constellation of Hercules.[10] It is easily visible to the naked eye under good observing conditions.
Properties
This is known to be a spectroscopic binary system,[11] although there is no information about the secondary component.[12] Based upon parallax measurements, this system is located at a distance of about Script error: No such module "convert". from the Earth.[1] The spectrum of the primary star matches a stellar classification of A9III, which indicates this is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. The effective temperature is about 7,031 K,[8] giving the star a white hue characteristic of A-type stars.[13] It is rotating rapidly with a projected rotational velocity of 135 km s−1.[9] The interferometry-measured angular diameter of this star is 0.95 ± 0.04 mas,[14] which, at its estimated distance, equates to a physical radius of about six times the radius of the Sun.[7]
Observations by German astronomer Ernst Zinner in 1929 gave indications that this may be a variable star. It was listed in the New Catalogue of Suspected Variable Stars (1981) with a magnitude range of 3.74 to 3.81. Further observations up to 1991 showed a pattern of small, slow variations with a magnitude variation of 0.05. These appeared to repeat semi-regularly with a period of 183.6 days, although the spectroscopic data presented a shorter period of 165.9 days.[15]
Name
It was a member of indigenous Arabic asterism al-Nasaq al-Sha'āmī, "the Northern Line" of al-Nasaqān "the Two Lines",[16] along with β Her (Kornephoros), γ Ser (Zheng, Ching) and β Ser (Chow).[17]
According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, al-Nasaq al-Sha'āmī or Nasak Shamiya were the title for three stars :β Ser as Nasak Shamiya I, γ Ser as Nasak Shamiya II, γ Her as Nasak Shamiya III (exclude β Her)[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 is represent eleven old states in China which is marking the right borderline of the enclosure, consisting of γ Herculis, β Herculis, κ Herculis, γ Serpentis, β Serpentis, δ Serpentis, α Serpentis, ε Serpentis, δ Ophiuchi, ε Ophiuchi and ζ Ophiuchi.[19] Consequently, the Chinese name for γ Herculis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx), represent Héjiān (河間), possibly Hejian Kingdom or Hejian Commandery (see Sima Yong, the Prince of Hejian and Liu Wuzhou).[20][21] Héjiān (河間) was westernized into Ho Keen by R.H. Allen, which was the meaning "between the river".[22]
References
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- ↑ a b Script error: No such module "citation/CS1".. The radius (R*) is given by:
- ↑ a b c Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ a b Template:Cite simbad
- ↑ Script error: No such module "citation/CS1".
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- ↑ a b Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ 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
- ↑ 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.
- ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 24 日 Template:Webarchive
- ↑ 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.
- ↑ Star Names - R.H.Allen p. 244
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