68 Ophiuchi
Binary star system in the constellation Ophiuchus
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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.[1] The system is located around 89.69 parsecs (292.5 ly) distant from the Sun, based on parallax,[2] and is drifting further away with a radial velocity of +6 km/s.[6]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus[1] |
| Right ascension | 18h 01m 45.19884s[2] |
| Declination | +01° 18′ 18.2775″[2] |
| Apparent magnitude (V) | 4.42[1] + 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[2] mas/yr Dec.: −13.29[2] mas/yr |
| Parallax (π) | 11.15±0.60 mas[2] |
| Distance | 290 ± 20 ly (90 ± 5 pc) |
| Absolute magnitude (MV) | −0.34[1] |
| 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 | |
| BD+01°3560, CCDM J18018+0118AB, GC 24534, HIP 88290, HR 6723, HD 164577, NSV 10009, SAO 123035, WDS J18018+0118AB | |
| Database references | |
| SIMBAD | data |
This is a visual 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] There is evidence that it is a close spectroscopic binary.[7] The secondary companion, component B, is of magnitude 7.48.[3][14]