A first magnitude star system, the brightest in the constellation Virgo and the 16th brightest in the sky. The name Spica is Latin for “ear of corn”. It is so named because it represents the ear of corn being held by the Virgin in the constellation Virgo.

Spica is about 262 light years away from us, and is moving away from the solar system at about 1 km/s.

Spica is actually a binary star composed of a blue giant or supergiant star similar to Beta Canis Majoris of 10.9 solar masses and a blue main sequence star of 6.8 solar masses. The pair revolve around their common centre of mass about once every four days. The stars are tidally locked (they permanently show the same face to each other, like the the moon does to the earth) and mutual gravitational attraction has stretched each star into an oblate spheroid (a sphere that has been squashed slightly at the poles). The stars are about 17,700,000 kilometres (11,000,000 miles) apart (centre to centre). As the two stars orbit and eclipse each other the magnitude of the system varies between 1.01 and 0.91.


References:
http://www.glyphweb.com/esky/default.htm?http://www.glyphweb.com/esky/stars/spica.html
http://einstein.stcloudstate.edu/Dome/constellns/spica.html
http://www.aas.org/publications/baas/v29n2/aas190/abs/S026007.html
http://mathworld.wolfram.com/OblateSpheroid.html
http://www.infoplease.com/ce6/sci/A0846267.html

Spi"ca (?), n.; pl. Spicae (#). [L., an ear, as of corn.]

1. Med.

A kind of bandage passing, by successive turns and crosses, from an extremity to the trunk; -- so called from its resemblance to a spike of a barley.

2. Astron.

A star of the first magnitude situated in the constellation Virgo.

 

© Webster 1913.

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