Gamma Herculis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hercules |
| Right ascension | 16h 21m 55.21440s[1] |
| Declination | +19° 09′ 11.2618″[1] |
| Apparent magnitude (V) | +3.75[2] |
| Characteristics | |
| Spectral type | A9 IIIbn[3] |
| U−B color index | +0.18[2] |
| B−V color index | +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 | 193 ± 3 ly (59.1 ± 0.8 pc) |
| Absolute magnitude (MV) | −0.12[6] |
| Details | |
| Radius | 6[7] R☉ |
| Luminosity | 92[6] L☉ |
| 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 |
| Other designations | |
| γ Her, 20 Herculis, BD+19°3086, HD 147547, HIP 80170, HR 6095, SAO 102107[10] | |
| Database references | |
| SIMBAD | data |
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
[edit ]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 193 light-years (59 parsecs) 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
[edit ]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, 天市右垣 (Tiān Shì Yòu Yuán), 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 天市右垣二 (Tiān Shì Zuǒ Yòu èr, English: the Second Star of Right Wall of Heavenly Market Enclosure), 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
[edit ]- ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752 , Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600
- ^ a b c Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N
- ^ Gray, R. O.; Garrison, R. F. (1989), "The early F-type stars – Refined classification, confrontation with Stromgren photometry, and the effects of rotation", Astrophysical Journal Supplement Series, 69: 301, Bibcode:1989ApJS...69..301G, doi:10.1086/191315
- ^ Samus, N. N.; Durlevich, O. V.; et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S, 1, Bibcode:2009yCat....102025S
- ^ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W
- ^ a b c Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971 , Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644
- ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1 . The radius (R*) is given by:
- {\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(10^{-3}\cdot 59.1\cdot 0.95)\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 12.0\cdot R_{\bigodot }\end{aligned}}}
- ^ a b c Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
- ^ a b Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1): 1, Bibcode:1970CoAsi.239....1B
- ^ a b "* gam Her". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2010年06月23日.
- ^ Mason, Brian D.; et al. (December 2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
- ^ Kaler, James B., "GAMMA HER (Gamma Herculis)", Stars, University of Illinois , retrieved 2012年01月02日
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012年03月18日, retrieved 2012年01月16日
- ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039
- ^ a b Bakos, G. A.; Tremko, J. (1991), "Photometry and spectroscopy of Gamma Herculis", Contributions of the Astronomical Observatory Skalnate Pleso, 21: 7–14, Bibcode:1991CoSka..21....7B
- ^ Kunitzsch, P.; Smart, T. (2006), A Dictionary of Modern Star names: A Short Guide to 254 Star names and Their Derivations (Second Revised ed.), Cambridge, MA: Sky Publishing, p. 31, ISBN 1-931559-44-9
- ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc, p. 243, ISBN 0-486-21079-0 , retrieved 2010年12月12日
- ^ 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
- ^ (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, ISBN 978-986-7332-25-7.
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 24 日 Archived 2011年05月22日 at the Wayback Machine
- ^ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived August 10, 2010, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ^ Star Names - R.H.Allen p. 244