Gamma Ophiuchi
Gamma Ophiuchi, Latinized from γ Ophiuchi, is a fourth-magnitude star in the constellation Ophiuchus. Together with Beta Ophiuchi, it forms the serpent-holder's right shoulder. The staris visible to the naked eye with an apparent visual magnitude of +3.75. Based upon an annual parallax shift of 31.73 mas as seen from Earth, it is located 103 light years from the Sun. It is moving closer to the Sun with a radial velocity of −7.6 km/s.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 17h 47m 53.55973s |
| Declination | +02° 42′ 26.2000″ |
| Apparent magnitude (V) | +3.753 |
| Characteristics | |
| Spectral type | A0 V or A1VnkA0mA0 |
| U−B color index | +0.040 |
| B−V color index | +0.033 |
| Astrometry | |
| Radial velocity (Rv) | −7.6±0.3 km/s |
| Proper motion (μ) | RA: −24.64 mas/yr Dec.: −74.42 mas/yr |
| Parallax (π) | 31.73 ± 0.21 mas |
| Distance | 102.8 ± 0.7 ly (31.5 ± 0.2 pc) |
| Absolute magnitude (MV) | +1.26 |
| Details | |
| Mass | 2.9 M☉ |
| Radius | 1.8 R☉ |
| Luminosity | 29 L☉ |
| Surface gravity (log g) | 4.03 cgs |
| Temperature | 9,506 K |
| Rotational velocity (v sin i) | 220 km/s |
| Age | 184+93 −134 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
It is known also as Muliphen, although at least two more stars are known with this name: Gamma Canis Majoris (often spelled as Muliphein) and Gamma Centauri (often spelled as Muhlifain).
This is an A-type main sequence star with a stellar classification of A0 V. Gray et al. (2003) lists a classification of A1VnkA0mA0, indicating it is of type A1 V with the calcium K-line and metallic lines of an A0 star. It is approximately 184 million years old and is spinning rapidly with a projected rotational velocity of 220 km/s. Gamma Ophiuchi has nearly three times the mass of the Sun and 1.8 times the Sun's radius. The star shines with 29 times the luminosity of the Sun, which is being emitted from its outer atmosphere at an effective temperature of 9506 K. It is radiating an excess emission of infrared, suggesting the presence of a circumstellar disk of dust at an orbital radius of 64 AU from the host star.