Mu Herculis

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**Mu Herculis Aa/B/C**
Observation data Epoch J2000
Constellation (pronunciation)	Hercules
Right ascension	17^h 46^m 27.5^s
Declination	+27° 43′ 14″
Apparent magnitude (V)	3.42/10.35/10.80
Characteristics
Spectral type	G5 IV/M3.5 V/M4 V
U-B color index	0.39/1.01
B-V color index	0.75/1.50
Variable type	Periodic
Astrometry
Radial velocity (R_v)	-16.1/-13.7 km/s
Proper motion (μ)	RA: -291.42/-77.62 mas/yr Dec.: -750.00/-270.12 mas/yr
Parallax (π)	119.02 ± 0.58 mas
Distance	27.4 ± 0.1 ly (8.4 ± 0.04 pc)
Absolute magnitude (M_V)	3.80/10.73/11.18
Details
Mass	1.1/0.31/0.31 M_☉
Radius	1.8/0.48/0.4 R_☉
Luminosity	2.2-2.7/0.005/0.003 L_☉
Temperature	5,500 K
Metallicity	130-300%
Rotation	20 km/s.
Age	? years
Other designations
86 Hercules, Gl 695 A/B/C, HR 6623 A/B/C, BD +27°2888, HD 161797, LHS 3326/3325, LTT 15266, GCTP 4060.00, SAO 85397, FK5 667, LDS 1002, LFT 1374, GC 24138, ADS 10786, HIP 86974.

Mu Herculis is a nearest star system about 27.4 light years from Earth in the constellation Hercules. Its main star, Mu Herculis A (possibly a binary) is fairly similar to the Sun although more highly evolved. Its mass is about 1.1 times that of the Sun, and it is beginning to expand to become a giant. Mu Herculis A and the binary itself pair B-C are separated by 286 AUs. On the other hand stars B-C are separated by 11.4 AUs. Their orbit is quite elliptic (e=0.18) and both stars swing each other between 9.4 and 13.5 AUs.

[edit] Mu Herculis Ab (or D)?

Star A is itself suspected to be a close binary with a low mass stellar or a large substellar companion, probably at 17.2 AUs in elliptic orbit (e=0.34). Nevertheless the existence of such an object has still not confirmed