106 Herculis

106 Herculis is a variable star in the northern constellation Hercules. It is visible to the naked eye as a faint, red-hued point of light with a baseline apparent visual magnitude of 4.96.^[3] Based on its parallax, it is estimated to lie 383 light-years (117 parsecs) away from the Sun.^[4] The star is moving closer to the Earth with a heliocentric radial velocity of -35 km/s.^[8]

106 Herculis

A light curve for 106 Herculis, plotted from TESS data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Hercules
Right ascension	18h 20m 17.91482s[2]
Declination	+21° 57′ 40.6622″[2]
Apparent magnitude (V)	4.96[3]
Characteristics
Spectral type	M0 III[4]
U−B color index	+1.98[5]
B−V color index	+1.58[5]
Variable type	suspected SR[6][7]
Astrometry
Radial velocity (Rv)	−35.20±0.29[8] km/s
Proper motion (μ)	RA: +18.105[2] mas/yr Dec.: -59.631[2] mas/yr
Parallax (π)	8.5067±0.1739 mas[2]
Distance	383 ± 8 ly (118 ± 2 pc)
Absolute magnitude (MV)	−0.664[8]
Details
Radius	44.32+2.70 −5.89[2] R☉
Luminosity	414.1±9.7[2] L☉
Surface gravity (log g)	1.56±0.09[4] cgs
Temperature	3,789±6[4] K
Metallicity [Fe/H]	0.00±0.03[4] dex
Rotational velocity (v sin i)	5.0±1.0[9] km/s
Other designations
106 Her, NSV 24405, BD+21°3390, HD 168720, HIP 89861, HR 6868, SAO 85941[10]
Database references
SIMBAD	data

Eggleton and Tokovinin (2008) listed this as a suspected binary star system consisting of two roughly equal components.^[11] It appears as an ageing red giant with a stellar classification of M0III. This is a suspected semiregular variable star with a very small amplitude and a period of 40 days or more.^[7] Having exhausted the supply of hydrogen at its core, it has expanded to 44^[2] times the Sun's radius. It is radiating around 414^[2] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of about 3,789 K.^[4]