41 Ophiuchi
Binary star system in the constellation Ophiuchus
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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]
(4.92 + 7.51)[3]
 | |
| 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]