Spica
Star
Spica — the brightest star in Virgo, about 250 light-years away: really a hot blue pair of stars so close they whirl around each other every four days, their mutual gravity pulling each into an egg shape. It marks the ear of wheat held by the maiden Virgo.
Open in 3D viewSee Spica in the live, interactive 3D map
Key facts
Mass
2.27 × 10³¹ kg
11.4 M☉
Radius
5,148,180 km
7.4× wider than the Sun
Surface temperature
22,400 K (22127 °C)
Luminosity
7.85 × 10³⁰ W
Spectral type
B1 III-IV + B2 V (hot spectroscopic binary)
Science
Physical
- Mass
- 2.27 × 10³¹ kg · 11.4 M☉
- Radius
- 5,148,180 km · 7.4× wider than the Sun
- Density
- 39.7 kg/m³ · 0.04× water
- Spectral type
- B1 III-IV + B2 V (hot spectroscopic binary)
Composition
- By mass
- A pair of hot, blue B-type stars orbiting every four days, so close that their mutual gravity distorts them into egg shapes and their combined brightness varies as they turn. The massive primary will end as a supernova. The figures here are for the primary.
Temperature
- Surface
- 22,400 K (22127 °C)
Radiation & temperature
- Surface temperature
- 22,400 K (22127 °C)
- Peak wavelength
- 129 nm · ultraviolet (invisible to the eye)
Discovery & history
- Method
- Naked-eye star
- Name
- 'Spica' — Latin for the ear of grain (spica virginis) held by Virgo; Alpha Virginis.
One of the stars whose slowly shifting position helped Hipparchus discover the precession of the equinoxes around 130 BC. Today it is known as a rotating, pulsating ellipsoidal binary of two hot B-type stars.
Images
Images from open archives · credit shown per image