Theta Ophiuchi
Template:Location mark Location of θ Ophiuchi (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 3.25 - 3.31[2] |
| Characteristics | |
| Spectral type | B2 IV[3] |
| U−B Template:Engvar | −0.86[4] |
| B−V Template:Engvar | −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 | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | −2.4[6] |
| Details | |
| θ Oph Aa | |
| Mass | Script error: No such module "val".[7] Template:Solar mass |
| Radius | Script error: No such module "val".[7] Template:Solar radius |
| Luminosity | Script error: No such module "val".[7] Template:Solar luminosity |
| Surface gravity (log g) | Script error: No such module "val".[8] cgs |
| Temperature | Script error: No such module "val".[8] K |
| Metallicity [Fe/H] | Script error: No such module "val".[9] dex |
| Rotational velocity (v sin i) | 30[10] km/s |
| Age | Script error: No such module "val".[7] Myr |
| θ Oph B | |
| Mass | 5.4[7] Template:Solar mass |
| Radius | Script error: No such module "val".[7] Template:Solar radius |
| Luminosity | Script error: No such module "val".[7] Template:Solar luminosity |
| Surface gravity (log g) | Script error: No such module "val".[7] cgs |
| Temperature | 17,700[7] K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Rotational velocity (v sin i) | 150[7] km/s |
| Age | Script error: No such module "val".[7] Myr |
| Other designations | |
| Template:Odlist[11] | |
| Database references | |
| SIMBAD | data |
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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. 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 Script error: No such module "convert". from Earth.[1] It is 1.8 degrees south of the ecliptic and therefore subject to lunar occultations and (very rarely) occulted by a planet. The next occultation by a planet will be by Mars on 3 October 2078.[12]
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 an estimated 8.0 to 8.6 times the mass of the Sun and 4.98 to 5.23 times the Sun's radius. Although only 15.8 to 24 million years old,[7] 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 between 4,740 and 6,230 times the luminosity of the Sun from its photosphere[7] at an effective temperature of about 22,260 K,[8] giving it the blue-white hue of a B-type star.[16]
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".[17] With ζ Oph, η Oph, and ξ Oph it formed the Persian Garafsa, the Serpent-tamer;[17] a 1971 NASA list of star names includes the name Garafsa for θ Oph.[18]
References
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- ↑ a b Script error: No such module "Citation/CS1".
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- ↑ a b c d e f g h i j k l m Script error: No such module "Citation/CS1".
- ↑ a b c Script error: No such module "citation/CS1".
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- ↑ Template:Cite simbad
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
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- ↑ Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
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