68 Ophiuchi
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. The system is located around 89.69 parsecs (292.5 ly) distant from the Sun, based on parallax, and is drifting further away with a radial velocity of +6 km/s.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 18h 01m 45.19884s |
| Declination | 1° 18′ 18.2775″ |
| Apparent magnitude (V) | 4.42 + 7.48 |
| Characteristics | |
| Spectral type | A2Vn |
| U−B color index | +0.02 |
| B−V color index | +0.04 |
| Astrometry | |
| Radial velocity (Rv) | +6.00 km/s |
| Proper motion (μ) | RA: +15.93 mas/yr Dec.: -13.29 mas/yr |
| Parallax (π) | 11.15 ± 0.60 mas |
| Distance | 290 ± 20 ly (90 ± 5 pc) |
| Absolute magnitude (MV) | -0.34 |
| Orbit | |
| 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 M☉ |
| Radius | 4.5 R☉ |
| Luminosity | 160 L☉ |
| Surface gravity (log g) | 3.76 cgs |
| Temperature | 9,594 K |
| Metallicity [Fe/H] | -0.14 dex |
| Rotational velocity (v sin i) | 201 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. The brighter member, component A, is an A-type main-sequence star of spectral type A2Vn, 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. 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. The secondary companion, component B, is of magnitude 7.48.