Theta Virginis

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.

θ Virginis

Location of θ Virginis (circled)
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]