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β Herculis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hercules
Right ascension 16h 30m 13.1999s[1]
Declination +21° 29′ 22.608″[1]
Apparent magnitude (V) 2.76 to 2.81[2]
Characteristics
Spectral type G7III / ?
(binary)[3]
U-B color index +0.69[4]
B-V color index +0.94[4]
R-I color index +0.47[4]
Astrometry
Radial velocity (Rv) −25.5 ± 0.9[1] km/s
Proper motion (μ) RA: −98.43[1] mas/yr
Dec.: −14.49[1] mas/yr
Parallax (π) 22.07 ± 1.00[1] mas
Distance 148 ± 7 ly
(45 ± 2 pc)
Absolute magnitude (MV) −0.5[5]
Details
Mass Primary / secondary:
2.9 / 0.9[6] M
Radius Primary:
20[3] R
Luminosity Primary:
175[3] L
Temperature Primary:
4900[3] K
Orbit[7] , Table 3.
Period (P) 410.6 d
Semimajor 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, CCDM J16302+2129A, FK5 618, GC 22193, HD 148856, HIP 80816, HR 6148, IDS 16260+2142 A, PPM 104935, SAO 84411, WDS 16302+2129A/Aa.[1][4][8]
Database references
SIMBAD data

Beta Herculis (Beta Her / β Herculis / β Her), which also has the name Kornephoros, is the brightest star in the constellation of Hercules.[3] It has an apparent visual magnitude which varies between 2.76 and 2.81.[2]

Although β Herculis appears to the naked eye to be a single star, W. W. Campbell discovered in July 1899 from spectroscopic measurements that its radial velocity towards the Sun varies, and concluded that it is a binary system of two stars.[9] An orbit for the binary was computed in 1908 from additional spectroscopic measurements.[10]

At Palomar Observatory, Antoine Labeyrie and others used speckle interferometry with the Hale Telescope to resolve the system in 1977.[11] The Hipparcos satellite observed the orbital motion of the primary relative to other stars,[12] and an orbit was computed in 2005 using spectroscopic data together with these measurements. The period of the system is around 410 days.[7]

The primary of the binary system is a G-type giant star.[1]

Naming and etymology

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


Visual companion

CCDM J16302+2129B
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hercules
Right ascension 16h 29m 55.5830s[13]
Declination +21° 29′ 42.516″[13]
Apparent magnitude (V) 10.7[13]
Characteristics
B-V color index 0.4[13]
V-R color index −2.1[13]
Astrometry
Proper motion (μ) RA: −1.60[13] mas/yr
Dec.: 11.60[13] mas/yr
Position (relative to A)
Epoch of observation 1991
Angular distance 247.5 [8]
Position angle 275° [8]
Other designations
BD+21 2934B, IDS 16260+2142 B, WDS 16302+2129B.[1][8]
Database references
SIMBAD data

β Herculis has a visual companion, CCDM J16302+2129B, which has an apparent visual magnitude of approximately 10.7. It is probably optical and not physically bound to β Herculis.[13][4]

References

  1. ^ a b c d e f g h i SV* ZI 1252 -- Spectroscopic binary, database entry, SIMBAD. Accessed on line September 18, 2008.
  2. ^ a b NSV 7778, database entry, New Catalogue of Suspected Variable Stars, the improved version, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line September 18, 2008.
  3. ^ a b c d e Kornephoros, Stars, Jim Kaler. Accessed on line September 18, 2008.
  4. ^ a b c d e 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. ^ From apparent magnitude and parallax.
  6. ^ The Visual Orbit, the Stellar Diameter and the Magnitude Difference of the Spectroscopic Binary β Herculis, X. P. Pan, M. Shao, M. M. Colavita, B. E. Hines, J. T. Armstrong, C. S. Denisson, M. Vivekanand, D. Mozurkewich, R. S. Simon, K. J. Johnston, Bulletin of the American Astronomical Society 22 (September 1990), p. 1335, Bibcode1990BAAS...22R1335P.
  7. ^ a b Astrometric orbits of SB9 stars, S. Jancart, A. Jorissen, C. Babusiaux, and D. Pourbaix, Astronomy and Astrophysics 442, #1 (October 2005), pp. 365–380, doi:10.1051/0004-6361:20053003, Bibcode2005A&A...442..365J.
  8. ^ a b c d Entry 16302+2129, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 18, 2008.
  9. ^ The variable velocity of β Herculis in the line of sight, W. W. Campbell, Astrophysical Journal 11 (1900), p. 140, Bibcode1900ApJ....11..140C, doi:10.1086/140674.
  10. ^ The orbit of β Herculis, H. C. Plummer, Lick Observatory Bulletin 5 (1908), pp. 24–26, Bibcode1908LicOB...5...24P.
  11. ^ The digital speckle interferometer: preliminary results on 59 stars and 3C 27, A. Blazit, D. Bonneau, L. Koechlin, and A. Labeyrie, Astrophysical Journal Letters 214 (June 1, 1977), pp. L79–L84, Bibcode1977ApJ...214L..79B.
  12. ^ HIP 80816, database entry, The Hipparcos and Tycho Catalogues, ESA, 1997, CDS ID I/239.
  13. ^ a b c d e f g h BD+21 2934B -- Star in double system, database entry, SIMBAD. Accessed on line September 18, 2008.
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