68 Ophiuchi
Binary star system in the constellation Ophiuchus / From Wikipedia, the free encyclopedia
68 Ophiuchi is a binary star system in the equatorial constellation of Ophiuchus. It is visible to the naked eye as a faint star with an apparent visual magnitude of 4.42.[2] The system is located around 89.69 parsecs (292.5 ly) distant from the Sun, based on parallax,[1] and is drifting further away with a radial velocity of +6 km/s.[6]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ophiuchus |
Right ascension | 18h 01m 45.19884s[1] |
Declination | 1° 18′ 18.2775″[1] |
Apparent magnitude (V) | 4.42[2] + 7.48[3] |
Characteristics | |
Spectral type | A2Vn[4] |
U−B color index | +0.02[5] |
B−V color index | +0.04[5] |
Astrometry | |
Radial velocity (Rv) | +6.00[6] km/s |
Proper motion (μ) | RA: +15.93[1] mas/yr Dec.: -13.29[1] mas/yr |
Parallax (π) | 11.15 ± 0.60 mas[1] |
Distance | 290 ± 20 ly (90 ± 5 pc) |
Absolute magnitude (MV) | -0.34[2] |
Orbit[7] | |
Period (P) | 175.74±4.65 yr |
Semi-major axis (a) | 1.090±0.027″ |
Eccentricity (e) | 0.831±0.035 |
Inclination (i) | 69.5±3.0° |
Longitude of the node (Ω) | 160.2±1.6° |
Periastron epoch (T) | 2019.87±1.48 |
Argument of periastron (ω) (secondary) | 78.9±4.7° |
Details | |
68 Oph A | |
Mass | 3.07[8] M☉ |
Radius | 4.5[9] R☉ |
Luminosity | 160[8] L☉ |
Surface gravity (log g) | 3.76[10] cgs |
Temperature | 9,594[8] K |
Metallicity [Fe/H] | -0.14[11] dex |
Rotational velocity (v sin i) | 201[8] km/s |
Other designations | |
Database references | |
SIMBAD | data |
This is a spectroscopic binary with an orbital period of 177 years and an eccentricity of 0.83.[7] The brighter member, component A, is an A-type main-sequence star of spectral type A2Vn,[4] a star that is currently fusing its core hydrogen. The 'n' suffix indicates "nebulous" lines due to rapid rotation. The star is suspected of varying between magnitudes 4.42 and 4.48.[12] It displays an infrared excess that matches a circumstellar disk of dust orbiting 32.5 AU from the star with a mean temperature of 160 K.[13] The secondary companion, component B, is of magnitude 7.48.[3][14]