Quadruple star system in the constellation Hercules
μ Herculis Location of μ Herculis (circled in red)
Observation dataEpoch J2000 Equinox J2000 Constellation Hercules μ Her Aab (μ1 Her) Right ascension 17h 46m 27.52667s [ 1] Declination +27° 43′ 14.4379″[ 1] Apparent magnitude (V)3.417 ± 0.014 [ 1] μ Her BC (μ2 Her) Right ascension 17h 46m 25.079s [ 2] Declination +27° 43′ 01.45″[ 2] Apparent magnitude (V)10.2 / 10.7[ 3] Characteristics μ Her Aab Spectral type G5IV[ 4] [ 5] U−Bcolor index +0.40[ 6] B−Vcolor index +0.76[ 6] μ Her BC Spectral type M3.5V[ 7] U−Bcolor index +1.00[ 6] B−Vcolor index +1.50[ 6] Astrometry μ Her Aab Radial velocity (Rv )−17.07 ± 0.12[ 8] km/s Proper motion (μ)RA: −291.66[ 1] mas /yr Dec.: −749.60[ 1] mas /yr Parallax (π)120.33± 0.16 mas [ 1] Distance 27.11 ± 0.04 ly pc ) Absolute magnitude (MV )3.82 ± 0.02[ 8] μ Her BC Proper motion (μ)RA: −343.35[ 9] mas /yr Dec.: −743.88[ 9] mas /yr Parallax (π)119.8871± 0.2055 mas [ 10] Distance 27.21 ± 0.05 ly pc ) Absolute magnitude (MV )+10.26[ 11] Position (relative to μ Her Aab) [ 12] Component μ Her BC Angular distance 35″ Orbit [ 5] Primary μ Her Aa Companion μ Her Ab Period (P)98.9 ± 22.7 yr Semi-major axis (a)2.9 ± 0.3″ Eccentricity (e)0.44 ± 0.06 Inclination (i)62.82 ± 4.66° Longitude of the node (Ω)80.4 ± 1.7° Periastron epoch (T)B 1921.1 ± 23.8Argument of periastron (ω)214 ± 16° Semi-amplitude 1 )1.12 ± 0.10 km/s Orbit [ 3] Primary μ Her B Companion μ Her C Period (P)43.127 ± 0.013 yr Semi-major axis (a)1.385 ± 0.038″ Eccentricity (e)0.1796 ± 0.0009 Inclination (i)66.06 ± 0.15° Longitude of the node (Ω)60.07 ± 0.17° Periastron epoch (T)B 2008.335 ± 0.073 Argument of periastron (ω)172.85 ± 0.64° Details μ Her Aa Mass +0.058 [ 13] M ☉ Radius +0.030 [ 13] R ☉ Luminosity ± 0.026[ 14] L ☉ Surface gravity (log g )± 0.025[ 14] cgs Temperature ± 22[ 14] K Metallicity [Fe/H] +± 0.04[ 14] dex Rotation +3 [ 8] Rotational velocity (v sin i )1.7 ± 0.4[ 8] Age +0.4 [ 13] Gyr μ Her Ab Mass 0.32[ 5] M ☉ μ Her B Mass 0.44[ 15] M ☉ Radius 0.60[ 16] R ☉ Luminosity 0.087[ 16] L ☉ Temperature 4,050[ 16] K Metallicity [Fe/H] +0.21[ 16] dex μ Her C Mass 0.39[ 15] M ☉ Radius ± 0.032[ 17] R ☉ Temperature ± 32[ 17] K Metallicity [ M / H ] {\displaystyle {\begin{smallmatrix}\left[{\ce {M}}/{\ce {H}}\right]\end{smallmatrix}}} [ 17] Other designations 86 Herculis,Gl 695,HR 6623,BD +27°2888,HD 161797,LHS 3326/3325,LTT 15266,SAO 85397,FK5 667, LFT 1374,GC 24138,ADS 10786,HIP 86974.[ 18] Database references SIMBAD μ Her Aab μ Her BC
Mu Herculis (μ Herculis ) is a nearby quadruplestar system about 27.1 light years from Earth in theconstellation Hercules . Its main star, Mu Herculis A is fairly similar to theSun although more highlyevolved with astellar classification of G5 IV. Since 1943, thespectrum of this star has served as one of the stable anchor points by which other stars are classified.[ 19] [ 8]
In the catalogue of stars in theCalendarium of Al Achsasi Al Mouakket , this star was designatedMarfak Al Jathih Al Aisr , which was translated intoLatin asCubitum Sinistrum Ingeniculi , meaningthe left elbow of kneeling man .[ 20]
InChinese ,天市左垣 Tiān Shì Zuǒ Yuán Left Wall of Heavenly Market Enclosure δ Herculis ,λ Herculis ,ο Herculis ,112 Herculis ,ζ Aquilae ,θ1 Serpentis ,η Serpentis ,ν Ophiuchi ,ξ Serpentis andη Ophiuchi .[ 21] Chinese name for μ Herculis itself is天市左垣三 Tiān Shì Zuǒ Yuán sān the Third Star of Left Wall of Heavenly Market Enclosure ), representJiuhe (九河, lit. meaningnine rivers ), possibly forJiujiang , the prefecture-level city in Jiangxi, China, which is the same literally meaning withJiuhe .[ 22] [ 23] Kew Ho appeared.[ 24]
Mu Herculis is a quadruple star system. The brightest star is a well-studiedG-type subgiant , whose parameters are precisely determined fromasteroseismology .[ 8] near-infrared spectroscopy .[ 5] red dwarf with aspectral type of M4V and a mass of 0.32 M ☉ .[ 5] 1 Herculis.
The secondary component, also known as Mu2 Herculis,[ 12] [ 25] [ 18] [ 3]
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