Spica

Spica
Location of Spica (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Pronunciation /ˈspkə/ or /ˈspkə/[1][2]
Right ascension 13h 25m 11.579s[3]
Declination −11° 09′ 40.75″[3]
Apparent magnitude (V) +0.97[4] (0.97–1.04[5])
Characteristics
Spectral type B1III-IV + B2V[6]
U−B color index −0.94[4]
B−V color index −0.23[4]
Variable type β Cep + Ellipsoidal[5]
Astrometry
Radial velocity (Rv)+1.0[7] km/s
Proper motion (μ) RA: −42.35±0.62[3] mas/yr
Dec.: −30.67±0.37[3] mas/yr
Parallax (π)13.06 ± 0.70 mas[3]
Distance250 ± 10 ly
(77 ± 4 pc)
Absolute magnitude (MV)−3.55 (−3.5/−1.5)[8]
Orbit[9]
Period (P)4.0145±0.0001 d
Semi-major axis (a)28.20±0.92 R
Eccentricity (e)0.133±0.017
Inclination (i)63.1±2.5°
Periastron epoch (T)2,454,189.4±0.02
Argument of periastron (ω)
(secondary)
255.6±12.2°
Details[9]
Primary
Mass11.43±1.15 M
Radius7.47±0.54 R
Luminosity20,512+5,015
−4,030
 L
Surface gravity (log g)3.71±0.10 cgs
Temperature25,300±500 K
Rotational velocity (v sin i)165.3±4.5 km/s
Age12.5 Myr
Secondary
Mass7.21±0.75 M
Radius3.74±0.53 R
Luminosity2,254+1,166
−768
 L
Surface gravity (log g)4.15±0.15 cgs
Temperature20,900±800 K
Rotational velocity (v sin i)58.8±1.5 km/s
Other designations
Spica, Azimech, Spica Virginis, α Virginis, Alpha Vir, 67 Virginis, BD−10°3672, FK5 498, HD 116658, HIP 65474, HR 5056, SAO 157923, CCDM 13252-1109[10]
Database references
SIMBADdata

Spica is the brightest object in the constellation of Virgo and one of the 20 brightest stars in the night sky. It has the Bayer designation α Virginis, which is Latinised to Alpha Virginis and abbreviated Alpha Vir or α Vir. Analysis of its parallax shows that it is located 250±10 light-years from the Sun.[3] It is a spectroscopic binary star and rotating ellipsoidal variable; a system whose two stars are so close together they are egg-shaped rather than spherical, and can only be separated by their spectra. The primary is a blue giant and a variable star of the Beta Cephei type.

Spica, along with Arcturus and Denebola—or Regulus, depending on the source—forms the Spring Triangle asterism, and, by extension, is also part of the Great Diamond together with the star Cor Caroli.

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  9. ^ a b Cite error: The named reference Tkachenko2016 was invoked but never defined (see the help page).
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