Beta Herculis

β Herculis
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
Evolutionary stage Red clump[3]
Spectral type G7 IIIa[4]
U−B color index +0.70[2]
B−V color index +0.91[2]
R−I color index +0.47[5]
Astrometry
Radial velocity (Rv)−25.5[6] km/s
Proper motion (μ) RA: −99.15[1] mas/yr
Dec.: −15.39[1] mas/yr
Parallax (π)23.44 ± 0.58 mas[1]
Distance139 ± 3 ly
(43 ± 1 pc)
Absolute magnitude (MV)−0.49 ± 0.10[7]
Details
A
Mass2.91±0.11[8] M☉
Radius15.92+0.39
−0.41[8] R☉
Luminosity153.7±0.8[8] L☉
Surface gravity (log g)2.5[9] cgs
Temperature5,092±64[8] K
Metallicity [Fe/H]−0.115[10] dex
Rotational velocity (v sin i)3.0[9] km/s
Age420±60[8] Myr
B
Mass0.9[11] M☉
Orbit
Period (P)1.1254±0.0001[12]
Semi-major axis (a)11.37 ± 0.51 mas[13]
0.504±0.034 AU[12]
Eccentricity (e)0.5613±0.0010[12]
Inclination (i)53.8 ± 2.3[13]°
Longitude of the node (Ω)341.9 ± 3.8[13]°
Periastron epoch (T)3310.9±9.3 JD[12]
Argument of periastron (ω)
(primary)		21.9±0.05[12]°
Semi-amplitude (K1)
(primary)		13.05±0.05[12] km/s
Other designations
Kornephoros, Korndeforos, 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.[5][14][15]
Database references
SIMBADdata

Beta Herculis (β Herculis, abbreviated Beta Her, β Her), formally named Kornephoros /kɔːrˈnɛfərəs/,[16] or Rutilicus, is a binary star and the brightest star in the northern constellation of Hercules[3] 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.[17] Based upon parallax measurements, it is located at a distance of 139 light-years (43 parsecs) from the Sun.[1]

Although Beta 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 has a companion.[18]

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  16. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
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