Eta Ophiuchi
Star in the constellation Ophiuchus / From Wikipedia, the free encyclopedia
Eta Ophiuchi (η Ophiuchi, abbreviated Eta Oph, η Oph) is a binary star in the constellation of Ophiuchus. Based on parallax measurements taken during the Hipparcos mission, it is approximately 88 light-years from the Sun.
Quick Facts Observation data Epoch J2000 Equinox J2000, Constellation ...
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ophiuchus |
Right ascension | 17h 10m 22.68689s[1] |
Declination | –15° 43′ 29.6639″[1] |
Apparent magnitude (V) | 2.43[2] (3.05/3.27)[3] |
Characteristics | |
Spectral type | A1 IV + A1 IV[3] |
U−B color index | +0.09[2] |
B−V color index | +0.05[2] |
Astrometry | |
Radial velocity (Rv) | –0.9[4] km/s |
Proper motion (μ) | RA: +40.13[1] mas/yr Dec.: +99.17[1] mas/yr |
Parallax (π) | 36.91 ± 0.80 mas[1] |
Distance | 88 ± 2 ly (27.1 ± 0.6 pc) |
Orbit[3] | |
Period (P) | 87.58 ± 1.00 yr |
Semi-major axis (a) | 1.396 ± 0.010″ |
Eccentricity (e) | 0.950 ± 0.020 |
Inclination (i) | 95.2 ± 2.0° |
Longitude of the node (Ω) | 38.9 ± 1.0° |
Periastron epoch (T) | 2024.68 ± 0.50 |
Argument of periastron (ω) (secondary) | 274.8 ± 2.0° |
Details | |
Metallicity [Fe/H] | −0.01[5] dex |
η Oph A | |
Mass | 2.966[3] M☉ |
Rotational velocity (v sin i) | 23[6] km/s |
η Oph B | |
Mass | 3.478[3] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
Close
Eta Ophiuchi is part of a multiple star system designated WDS J17104-1544. It itself is designated WDS J17104-1544AB and its two components WDS J17104-1544A (also called Sabik /ˈseɪbɪk/, the traditional name for the system)[7][8] and WDS J17104-1544B. The 'C' component is UCAC4 372-080717[9] and 'D' is UCAC2 26022336.[10]