Theta Virginis
Multiple star system in the constellation of Virgo From Wikipedia, the free encyclopedia
Theta Virginis (θ Vir, θ Virginis) is a multiple star system in the zodiac constellation of Virgo. Based upon parallax measurements, it is about 320 light years from the Sun. The three[10] stars in this system have a combined apparent visual magnitude of 4.37,[2] bright enough to be seen with the naked eye.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Virgo |
| Right ascension | 13h 09m 56.99067s[1] |
| Declination | −05° 32′ 20.4185″[1] |
| Apparent magnitude (V) | 4.37[2] (4.49 + 6.83 + 9.4 + 10.4)[3] |
| Characteristics | |
| Spectral type | A1Vs[4] + ? + A9m + ?[3] |
| U−B color index | +0.00[2] |
| B−V color index | −0.02[2] |
| Astrometry | |
| Radial velocity (Rv) | −2.9[5] km/s |
| Proper motion (μ) | RA: −36.28[1] mas/yr Dec.: −31.22[1] mas/yr |
| Parallax (π) | 10.33±1.09 mas[1] |
| Distance | approx. 320 ly (approx. 100 pc) |
| Absolute magnitude (MV) | −0.52[6] |
| Details | |
| θ Vir Aa | |
| Mass | 3.11±0.11[7] M☉ |
| Radius | 4.03±0.30[8] R☉ |
| Luminosity | 130+22 −19[8] L☉ |
| Surface gravity (log g) | 3.61±0.11[8] cgs |
| Temperature | 9,600±140[8] K |
| Metallicity [Fe/H] | 0.15±0.14[8] dex |
| Rotational velocity (v sin i) | 4±1[4] km/s |
| Other designations | |
| 51 Virginis, θ Vir, BD−04°3430, FK5 490, HD 114330, HIP 64238, HR 4963, SAO 139189.[9] | |
| Database references | |
| SIMBAD | data |
The primary component, Theta Virginis Aa, is a white-hued A-type main sequence star with a stellar classification of A1Vs.[4] It is part of a spectroscopic binary[11] which components, Aa and Ab, have visual magnitudes of +4.49 and +6.83 respectively. The system has an orbital period of about 33.04 years with an eccentricity of 0.9.[3] The brighter member of this pair shows photometric and radial velocity periodicities with a cycle time of 0.7 days, which may indicate its rotation period.[12]
The inner pair is orbited by the 9.4 magnitude B component, at an angular separation of 7.1 arcseconds. A fourth component C, 69.6 arcseconds away, has an apparent magnitude of 10.4.[3] However, component C is an optical companion: it is physically unrelated and only appears close in the sky.[10]
On 11 November 2028 and again 11 November 2036, it will have close conjunctions with Venus.[13]: 167
Coincidentally on 11 November 2044 Venus will occult it just 41 days after occulting the bright star Regulus.[14]
References
External links
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