41 Ophiuchi

41 Ophiuchi is a binary star^[8] system in the zodiac constellation of Ophiuchus, and is positioned less than half a degree to the south of the celestial equator. It is visible to the naked eye as a faint, orange-hued point of light with a combined apparent visual magnitude of 4.72.^[2] The distance to this system is approximately 202 light years based on parallax.^[12]

41 Ophiuchi

Location of 41 Ophiuchi (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Ophiuchus
Right ascension	17h 16m 36.68653s[1]
Declination	−00° 26′ 43.0915″[1]
Apparent magnitude (V)	4.72[2] (4.92 + 7.51)[3]
Characteristics
Evolutionary stage	horizontal branch[4]
Spectral type	K2III[5]
U−B color index	+1.11[6]
B−V color index	+1.15[6]
Astrometry
Radial velocity (Rv)	−0.16[7] km/s
Proper motion (μ)	RA: −31.645[1] mas/yr Dec.: −57.144[1] mas/yr
Parallax (π)	16.1517±0.2358 mas[1]
Distance	202 ± 3 ly (61.9 ± 0.9 pc)
Absolute magnitude (MV)	0.72[2]
Orbit[8]
Period (P)	140.76±0.23 yr
Semi-major axis (a)	0.959±0.008″
Eccentricity (e)	0.866±0.003
Inclination (i)	65.1±0.0°
Longitude of the node (Ω)	220.5±0.0°
Periastron epoch (T)	1890.53±0.36 B
Argument of periastron (ω) (secondary)	287.5±0.0°
Details
41 Oph A
Mass	1.46[9] M☉
Radius	11.80+0.27 −0.39[1] R☉
Luminosity	60.3±1.0[1] L☉
Surface gravity (log g)	2.42[10] cgs
Temperature	4,509±65[9] K
Metallicity [Fe/H]	+0.06[2] dex
Rotational velocity (v sin i)	2.6[7] km/s
Age	3.73[9] Gyr
Other designations
41 Oph, BD−00°3255, GC 23320, HD 156266, HIP 84514, HR 6415, SAO 141586, CCDM J17166-0027AB, WDS J17166-0027[11]
Database references
SIMBAD	data

This is a visual binary with an orbital period of 141 years and an eccentricity of 0.866.^[8] The magnitude 4.92^[3] primary, designated component A, is an aging K-type giant star with a stellar classification of K2III.^[5] It is a red clump giant,^[4] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is 3.7^[9] billion years old with 1.46^[9] times the mass of the Sun and has expanded to nearly 12^[1] times the Sun's radius. It is radiating 60^[1] times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,509 K.^[9]

The secondary companion, component B, has a visual magnitude of 7.51 and an angular separation of 0.70″ from the primary along a position angle of 22°, as of 2017.^[3]