Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ophiuchus |
Right ascension | 17h 22m 00.57935s [1] |
Declination | −24° 59′ 58.3670″ [1] |
Apparent magnitude (V) | 3.25 - 3.31 [2] |
Characteristics | |
Spectral type | B2 IV [3] |
U−B color index | −0.86 [4] |
B−V color index | −0.23 [4] |
Variable type | β Cep [2] |
Astrometry | |
Radial velocity (Rv) | −2 [5] km/s |
Proper motion (μ) |
RA: −7.37
[1]
mas/
yr Dec.: −23.94 [1] mas/ yr |
Parallax (π) | 7.48 ± 0.17 mas [1] |
Distance | 436 ± 10
ly (134 ± 3 pc) |
Absolute magnitude (MV) | −2.4 [6] |
Details | |
Mass | 8.8±0.2 [3] M☉ |
Radius | 6.3 [7] R☉ |
Luminosity | 5,000 [6] L☉ |
Surface gravity (log g) | 3.950±0.006 [8] cgs |
Temperature | 22,260±280 [8] K |
Metallicity [Fe/H] | −0.15±0.12 [9] dex |
Rotational velocity (v sin i) | 30 [10] km/s |
Age | 21.3±5.8 [3] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Theta Ophiuchi, Latinized from θ Ophiuchi, is a multiple star system in the equatorial constellation of Ophiuchus. It lies on the "right foot" of the serpent-bearer, just southwest of Kepler's Star, the nova of 1604. According to Richard H. Allen's Star Names: Their Lore and Meaning (1899), θ Oph together with ξ Oph formed the Sogdian Wajrik "the Magician", the Khorasmian Markhashik "the Serpent-bitten" and with η Oph the Coptic Tshiō, "the Snake", and Aggia, "the Magician". [12] This star has an apparent visual magnitude of +3.3, [6] making it readily visible to the naked eye. Based upon parallax measurements from the Hipparcos mission, it is roughly 436 light-years (134 parsecs) from Earth. [1] It is 1.8 degrees south of the ecliptic and therefore subject to lunar occultations and less frequently occulted by a planet.
Theta Ophiuchi appears to be a triple star system. The brightest component is a spectroscopic binary with an orbital period of 56.71 days and an eccentricity of 0.17. The third component is 5.5 magnitude star with a stellar classification of B5. Its angular separation from the binary pair is 0.15 arcseconds. [13] This system is a proper motion member of the Upper Scorpius sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun. [6]
The primary component of this system is a variable star of the Beta Cephei type with a period of just 3h 22m. [15] It has nearly nine [3] times the mass of the Sun and more than six [7] times the Sun's radius. Although only 21 million years old, [3] it has begun to evolve away from the main sequence and has become a subgiant star with a stellar classification of B2 IV. [3] This massive star is radiating around 5,000 times the luminosity of the Sun from its outer atmosphere at an effective temperature of about 22,260 K, [8] giving it the blue-white hue of a B-type star. [16]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ophiuchus |
Right ascension | 17h 22m 00.57935s [1] |
Declination | −24° 59′ 58.3670″ [1] |
Apparent magnitude (V) | 3.25 - 3.31 [2] |
Characteristics | |
Spectral type | B2 IV [3] |
U−B color index | −0.86 [4] |
B−V color index | −0.23 [4] |
Variable type | β Cep [2] |
Astrometry | |
Radial velocity (Rv) | −2 [5] km/s |
Proper motion (μ) |
RA: −7.37
[1]
mas/
yr Dec.: −23.94 [1] mas/ yr |
Parallax (π) | 7.48 ± 0.17 mas [1] |
Distance | 436 ± 10
ly (134 ± 3 pc) |
Absolute magnitude (MV) | −2.4 [6] |
Details | |
Mass | 8.8±0.2 [3] M☉ |
Radius | 6.3 [7] R☉ |
Luminosity | 5,000 [6] L☉ |
Surface gravity (log g) | 3.950±0.006 [8] cgs |
Temperature | 22,260±280 [8] K |
Metallicity [Fe/H] | −0.15±0.12 [9] dex |
Rotational velocity (v sin i) | 30 [10] km/s |
Age | 21.3±5.8 [3] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Theta Ophiuchi, Latinized from θ Ophiuchi, is a multiple star system in the equatorial constellation of Ophiuchus. It lies on the "right foot" of the serpent-bearer, just southwest of Kepler's Star, the nova of 1604. According to Richard H. Allen's Star Names: Their Lore and Meaning (1899), θ Oph together with ξ Oph formed the Sogdian Wajrik "the Magician", the Khorasmian Markhashik "the Serpent-bitten" and with η Oph the Coptic Tshiō, "the Snake", and Aggia, "the Magician". [12] This star has an apparent visual magnitude of +3.3, [6] making it readily visible to the naked eye. Based upon parallax measurements from the Hipparcos mission, it is roughly 436 light-years (134 parsecs) from Earth. [1] It is 1.8 degrees south of the ecliptic and therefore subject to lunar occultations and less frequently occulted by a planet.
Theta Ophiuchi appears to be a triple star system. The brightest component is a spectroscopic binary with an orbital period of 56.71 days and an eccentricity of 0.17. The third component is 5.5 magnitude star with a stellar classification of B5. Its angular separation from the binary pair is 0.15 arcseconds. [13] This system is a proper motion member of the Upper Scorpius sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun. [6]
The primary component of this system is a variable star of the Beta Cephei type with a period of just 3h 22m. [15] It has nearly nine [3] times the mass of the Sun and more than six [7] times the Sun's radius. Although only 21 million years old, [3] it has begun to evolve away from the main sequence and has become a subgiant star with a stellar classification of B2 IV. [3] This massive star is radiating around 5,000 times the luminosity of the Sun from its outer atmosphere at an effective temperature of about 22,260 K, [8] giving it the blue-white hue of a B-type star. [16]