Beta Herculis

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β Herculis
Diagram showing star positions and boundaries of the Hercules constellation and its surroundings
Cercle rouge 100%.svg

Location of β Herculis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hercules
Right ascension 16h 30m 13.19955s[1]
Declination +21° 29′ 22.6008″[1]
Apparent magnitude (V) 2.81[2]
Characteristics
Spectral type G7 IIIa[3]
U−B color index +0.70[2]
B−V color index +0.91[2]
R−I color index +0.47[4]
Astrometry
Radial velocity (Rv) −25.5[5] km/s
Proper motion (μ) RA: −99.15[1] mas/yr
Dec.: −15.39[1] mas/yr
Parallax (π) 23.44 ± 0.58[1] mas
Distance 139 ± 3 ly
(43 ± 1 pc)
Absolute magnitude (MV) −0.49 ± 0.10[6]
Details
A
Mass 2.9[7] M
Radius 17[8] R
Luminosity 151[8] L
Surface gravity (log g) 2.5[8] cgs
Temperature 4,887[8] K
Metallicity [Fe/H] –0.27[8] dex
Rotational velocity (v sin i) 3.0[8] km/s
B
Mass 0.9[7] M
Orbit[9]
Period (P) 410.6 d
Semi-major axis (a) 11.37 ± 0.51 mas
Eccentricity (e) 0.55
Inclination (i) 53.8 ± 2.3°
Longitude of the node (Ω) 341.9 ± 3.8°
Periastron epoch (T) 15500.4 MJD
Argument of periastron (ω)
(primary)
24.6°
Other designations
Kornephoros, Korneforos, Rutilicus, β Her, Beta Herculis, Beta Her, 27 Herculis, 27 Her, BD+21 2934, FK5 618, HD 148856, HIP 80816, HR 6148, SAO 84411, WDS 16302+2129A/Aa.[4][10][11]
Database references
SIMBAD data

Beta Herculis (Beta Her, β Herculis, β Her), which has the traditional name Kornephoros, is the brightest star in the northern constellation of Hercules[12] at a base apparent visual magnitude of 2.81. This is a suspected variable star with an apparent magnitude that may rise as high as 2.76.[13] Based upon parallax measurements, it is located at a distance of 139 light-years (43 parsecs) from Earth.[1]

Although β Herculis appears to the naked eye to be a single star, in July 1899 the American astronomer W. W. Campbell discovered from spectroscopic measurements that its radial velocity varies, and concluded that it is a binary system.[14] An orbit for the binary was computed in 1908 based upon additional spectroscopic measurements.[15]

At Palomar Observatory, Antoine Labeyrie and others used speckle interferometry with the Hale Telescope to resolve the system in 1977.[16] The Hipparcos satellite observed the orbital motion of the primary relative to other stars,[17] and an orbit was computed in 2005 using spectroscopic data together with these measurements. The period of the system is around 410 days. They have a high orbital eccentricity of 0.55 and the orbital plane is inclined 53.8° to the line of sight from the Earth.[9]

The primary star in this binary system has a stellar classification of G7 IIIa,[3] indicating that it is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. It has a mass nearly three times the mass of the Sun, and has expanded to 17 times the Sun's radius.[8] The effective temperature of the star's outer envelope is about 4,887 K,[8] which gives it the yellow hue of a G-type star.[18] The secondary star has a mass only 90% that of the Sun.[3]

Naming and etymology[edit]

β Herculis has the names Kornephoros, a Greek word meaning "club bearer", and Rutilicus, a corruption of the Latin word titillicus, meaning "armpit".

It was a member of indigenous Arabic asterism al-Nasaq al-Shāmī, "the Northern Line" of al-Nasaqān "the Two Lines",[19] along with γ Her (Hejian, Ho Keen), γ Ser (Zheng, Ching) and β Ser (Chow).[20]

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 this star)[21]

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 β Herculis, γ Herculis, κ Herculis, γ Serpentis, β Serpentis, δ Serpentis, α Serpentis, ε Serpentis, δ Ophiuchi, ε Ophiuchi and ζ Ophiuchi.[22] Consequently, β Herculis itself is known as 天市右垣一 (Tiān Shì Zuǒ Yòu yī, English: the First Star of Right Wall of Heavenly Market Enclosure), represent Hézhōng (河中), possibly Hezhong Municipality or Hezhong Circuit (see : Wang Chongrong, formally the Prince of Langye 瑯琊王, was a warlord of the late Chinese dynasty Tang Dynasty who controlled Hezhong Circuit, headquartered in modern Yuncheng, Shanxi).[23][24] Hézhōng (河中) was westernized into Ho Chung by R.H. Allen, which means "in the river".[25]

Namesakes[edit]

USS Ruticulus (AK-113) was a United States Navy Crater class cargo ship named after the star.

References[edit]

  1. ^ 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 
  2. ^ a b c Fernie, J. D. (May 1983), "New UBVRI photometry for 900 supergiants", Astrophysical Journal Supplement Series 52: 7–22, Bibcode:1983ApJS...52....7F, doi:10.1086/190856 
  3. ^ a b c Cayrel de Strobel, G.; Soubiran, C.; Ralite, N. (July 2001), "Catalogue of [Fe/H] determinations for FGK stars: 2001 edition", Astronomy and Astrophysics 373: 159–163, arXiv:astro-ph/0106438, Bibcode:2001A&A...373..159C, doi:10.1051/0004-6361:20010525 
  4. ^ a b HR 6148, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 18, 2008.
  5. ^ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W 
  6. ^ Carney, Bruce W. et al. (March 2008), "Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars", The Astronomical Journal 135 (3): 892–906, arXiv:0711.4984, Bibcode:2008AJ....135..892C, doi:10.1088/0004-6256/135/3/892 
  7. ^ a b Pan, X. P. et al. (September 1990), "The Visual Orbit, the Stellar Diameter and the Magnitude Difference of the Spectroscopic Binary β Herculis", Bulletin of the American Astronomical Society 22: 1335, Bibcode:1990BAAS...22R1335P 
  8. ^ a b c d e f g h 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 
  9. ^ a b Jancart, S. et al. (October 2005), "Astrometric orbits of SB^9 stars", Astronomy and Astrophysics 442 (1): 365–380, arXiv:astro-ph/0507695, Bibcode:2005A&A...442..365J, doi:10.1051/0004-6361:20053003 
  10. ^ SV* ZI 1252 -- Spectroscopic binary, database entry, SIMBAD. Accessed on line September 18, 2008.
  11. ^ Entry 16302+2129, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 18, 2008.
  12. ^ Kaler, James B., "Kornephoros", Stars (University of Illinois), retrieved 2008-09-18 
  13. ^ NSV 7778, database entry, New Catalogue of Suspected Variable Stars, the improved version, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line September 18, 2008.
  14. ^ Campbell, W. W. (1900), "The variable velocity of β Herculis in the line of sight", Astrophysical Journal 11: 140, Bibcode:1900ApJ....11..140C, doi:10.1086/140674 
  15. ^ Plummer, H. C. (1908), "The orbit of β Herculis", Lick Observatory Bulletin 5: 24–26, Bibcode:1908LicOB...5...24P, doi:10.5479/ADS/bib/1908LicOB.5.24P 
  16. ^ Blazit, A.; Bonneau, D.; Koechlin, L.; Labeyrie, A. (June 1, 1977), "The digital speckle interferometer: preliminary results on 59 stars and 3C 27", Astrophysical Journal Letters 214: L79–L84, Bibcode:1977ApJ...214L..79B, doi:10.1086/182447 
  17. ^ HIP 80816, database entry, The Hipparcos and Tycho Catalogues, ESA, 1997, CDS ID I/239.
  18. ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16 
  19. ^ 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 
  20. ^ 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 2010-12-12 
  21. ^ 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
  22. ^ (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.
  23. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  24. ^ (Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name, Hong Kong Space Museum. Accessed on line November 23, 2010.
  25. ^ Star Names - R.H.Allen p. 244