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Zeta Ophiuchi
O-type main sequence star in the constellation Ophiuchus / From Wikipedia, the free encyclopedia
Zeta Ophiuchi (ζ Oph, ζ Ophiuchi) is a single[9] star located in the constellation of Ophiuchus. It has an apparent visual magnitude of 2.6, making it the third-brightest star in the constellation. Parallax measurements give an estimated distance of roughly 440 light-years (130 parsecs) from the Earth.[1] It is surrounded by the Sh2-27 "Cobold" nebula, the star's bow shock as it ploughs through dense dust clouds near the Rho Ophiuchi cloud complex.
Quick Facts Observation data Epoch J2000 Equinox J2000, Constellation ...
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ophiuchus |
Right ascension | 16h 37m 09.54001s[1] |
Declination | −10° 34′ 01.5097″[1] |
Apparent magnitude (V) | 2.56 – 2.58[2] |
Characteristics | |
Spectral type | O9.5 V[3] |
U−B color index | −0.857[4] |
B−V color index | +0.032[4] |
Variable type | γ Cas[2] + β Cep[3] |
Astrometry | |
Radial velocity (Rv) | −15.0[5] km/s |
Proper motion (μ) | RA: +10.465 mas/yr[1] Dec.: +24.742 mas/yr[1] |
Parallax (π) | 7.4088 ± 0.6596 mas[1] |
Distance | 440 ± 40 ly (130 ± 10 pc)[1] |
Absolute magnitude (MV) | −4.2[6] |
Details | |
Mass | 20.2[7] M☉ |
Radius | 9.1 (equator) 7.5 (polar)[6] R☉ |
Luminosity | 74,100[7] L☉ |
Surface gravity (log g) | 3.58[6] cgs |
Temperature | 30,700 (equatorial) 39,000 (polar)[6] K |
Rotational velocity (v sin i) | 400[3] km/s |
Age | 3.0±0.3[8] Myr |
Other designations | |
Database references | |
SIMBAD | data |
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In April 2010, ζ Ophiuchi was occulted by asteroid 824 Anastasia.[10][11][12]