Gamma Ophiuchi
Star in the constellation Ophiuchus
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Gamma Ophiuchi, Latinized from γ Ophiuchi, formally named Bake-eo,[10] is a fourth-magnitude star in the constellation Ophiuchus. Together with Beta Ophiuchi, it forms the serpent-holder's right shoulder.[11] The star is visible to the naked eye with an apparent visual magnitude of +3.75.[2] 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.[6]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 17h 47m 53.55973s[1] |
| Declination | +02° 42′ 26.2000″[1] |
| Apparent magnitude (V) | +3.753[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | A0 V[4] or A1VnkA0mA0[5] |
| U−B color index | +0.040[2] |
| B−V color index | +0.033[2] |
| Astrometry | |
| Radial velocity (Rv) | −7.6±0.3[6] km/s |
| Proper motion (μ) | RA: −24.64[1] mas/yr Dec.: −74.42[1] mas/yr |
| Parallax (π) | 31.73±0.21 mas[1] |
| Distance | 102.8 ± 0.7 ly (31.5 ± 0.2 pc) |
| Absolute magnitude (MV) | +1.26[6] |
| Details | |
| Mass | 2.9[4] M☉ |
| Radius | 2.01±0.02[7] R☉ |
| Luminosity | 24.5±0.5[7] L☉ |
| Surface gravity (log g) | 4.03[5] cgs |
| Temperature | 9,070±100[7] K |
| Rotational velocity (v sin i) | 220[8] km/s |
| Age | 184+93 −134[8] Myr |
| Other designations | |
| Bake-eo, Bake Eo, γ Oph, 62 Ophiuchi, BD+02 3403, FK5 668, GC 24162, HD 161868, HIP 87108, HR 6629, SAO 122754[9] | |
| Database references | |
| SIMBAD | data |
Nomenclature
This star is known also as Muliphen,[12][13] 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).[13] Muliphein is the IAU-approved name of Gamma Canis Majoris.[10]
This star has the Marshallese name Bake-eo (or Bake Eo, pronounced "bakey-yew"), which refers to the spondylus mussel. The IAU Working Group on Star Names approved the name Bake-eo for γ Ophiuchi on 20 August 2024 and it is now so entered in the IAU Catalog of Star Names.[10]
In Chinese astronomy, β Ophiuchi and γ Ophiuchi form the asterism Zongzheng (宗正),[14] which was transliterated as Tsung Ching by R. H. Allen.[12]
Description
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This is an A-type main sequence star with a stellar classification of A0 V.[4] Gray et al. (2003) lists a classification of A1VnkA0mA0,[5] indicating it is of type A1 V with the calcium K-line and metallic lines of an A0 star. It is approximately 184[8] million years old and is spinning rapidly with a projected rotational velocity of 220 km/s.[8] Gamma Ophiuchi has nearly three times the mass of the Sun and 1.8 times the Sun's radius.[15] The star shines with 29[4] times the luminosity of the Sun, which is being emitted from its outer atmosphere at an effective temperature of 9506 K.[4] 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.[4] The disk was imaged in 2025.[7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| circumstellar disc | 124+6 −5 AU |
68±2° | — | |||