Mu Herculis
Historical view of the Hercules constellation showing Mu Herculis (μ Her) as one of stars in the hero's elbow. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hercules |
| μ Her Aab (μ1 Her) | |
| Right ascension | 17h 46m 27.52667s |
| Declination | +27° 43′ 14.4379″ |
| Apparent magnitude (V) | 3.417 ± 0.014 |
| μ Her BC (μ2 Her) | |
| Right ascension | 17h 46m 25.079s |
| Declination | +27° 43′ 01.45″ |
| Apparent magnitude (V) | 10.2 / 10.7 |
| Characteristics | |
| μ Her Aab | |
| Spectral type | G5IV / M4V |
| U−B color index | +0.40 |
| B−V color index | +0.76 |
| μ Her BC | |
| Spectral type | M3.5V |
| U−B color index | +1.00 |
| B−V color index | +1.50 |
| Astrometry | |
| μ Her Aab | |
| Radial velocity (Rv) | −17.07 ± 0.12 km/s |
| Proper motion (μ) | RA: −291.66 mas/yr Dec.: −749.60 mas/yr |
| Parallax (π) | 120.33±0.16 mas |
| Distance | 27.11 ± 0.04 ly (8.31 ± 0.01 pc) |
| Absolute magnitude (MV) | 3.82 ± 0.02 |
| μ Her BC | |
| Proper motion (μ) | RA: −343.35 mas/yr Dec.: −743.88 mas/yr |
| Parallax (π) | 119.8871 ± 0.2055 mas |
| Distance | 27.21 ± 0.05 ly (8.34 ± 0.01 pc) |
| Absolute magnitude (MV) | +10.26 |
| Position (relative to μ Her Aab) | |
| Component | μ Her BC |
| Angular distance | 35″ |
| Orbit | |
| 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 ± 23.8 |
| Argument of periastron (ω) (secondary) | 214 ± 16° |
| Semi-amplitude (K1) (primary) | 1.12 ± 0.10 km/s |
| Orbit | |
| 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) (secondary) | 172.85 ± 0.64° |
| Details | |
| μ Her Aa | |
| Mass | 1.11 ± 0.01 M☉ |
| Radius | 1.704±0.016 R☉ |
| Luminosity | 2.557±0.026 L☉ |
| Surface gravity (log g) | 4.020±0.025 cgs |
| Temperature | 5,596±22 K |
| Metallicity [Fe/H] | +0.26±0.04 dex |
| Rotation | 52+3 −1 d |
| Rotational velocity (v sin i) | 1.7 ± 0.4 km/s |
| Age | 7.8+0.3 −0.4 Gyr |
| μ Her Ab | |
| Mass | 0.32 M☉ |
| μ Her B | |
| Mass | 0.44 M☉ |
| Radius | 0.60 R☉ |
| Luminosity | 0.087 L☉ |
| Temperature | 4,050 K |
| Metallicity [Fe/H] | +0.21 dex |
| μ Her C | |
| Mass | 0.39 M☉ |
| Radius | 0.273±0.032 R☉ |
| Temperature | 3,100±32 K |
| Metallicity | = 0.39 |
| 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. | |
| Database references | |
| SIMBAD | μ Her Aab |
| μ Her BC | |
![{\displaystyle {\begin{smallmatrix}\left[{\ce {M}}/{\ce {H}}\right]\end{smallmatrix}}}](./d9a106d03666c72cc54c1dff07a5637d3adda9a1.svg)
Mu Herculis (μ Herculis) is a nearby quadruple star system about 27.1 light years from Earth in the constellation Hercules. Its main star, Mu Herculis A is fairly similar to the Sun although more highly evolved with a stellar classification of G5 IV. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Its mass is about 1.1 times that of the Sun, and it is beginning to expand to become a giant.