![]() Initially, the orbital parameters for this system were inferred using spectroscopic measurements. The changes in the orbital motion of this pair results in a Doppler shift in the absorption lines of their respective spectra, making them a double-lined spectroscopic binary. They stay close enough together that they cannot be resolved as two stars through a telescope. Spica is a close binary star whose components orbit each other every four days. This applies to α Virginis on 12 April, in the current astronomical epoch. Stars that can set (not in a circumpolar constellation for the viewer) culminate at midnight-noticeable where viewed away from any polar region experiencing midnight sun-when at opposition, meaning they can be viewed from dusk until dawn. This can be recalled by the mnemonic phrase, "arc to Arcturus and spike to Spica." Ī method of finding Spica is to follow the arc of the handle of the Big Dipper (or Plough) to Arcturus, and then continue on the same angular distance to Spica. Every 8 years, Venus passes Spica around the time of the star's heliacal rising, as in 2009 when it passed 3.5° north of the star on November 3. The Sun passes a little more than 2° north of Spica around October 16 every year, and the star's heliacal rising occurs about two weeks later. ![]() The next occultation will occur on September 2, 2197, when Venus again passes in front of Spica. The last planetary occultation of Spica occurred when Venus passed in front of the star (as seen from Earth) on November 10, 1783. Spica is 2.06 degrees from the ecliptic and can be occulted by the Moon and sometimes by planets. ![]() Nicolaus Copernicus made many observations of Spica with his home-made triquetrum for his researches on precession. A temple to Menat (an early Hathor) at Thebes was oriented with reference to Spica when it was built in 3200 BC, and, over time, precession slowly but noticeably changed Spica's location relative to the temple. Spica is believed to be the star that gave Hipparchus the data that led him to discover the precession of the equinoxes. Observational history Spica is the brightest star in the constellation of Virgo (lower left).Īs one of the nearest massive binary star systems to the Sun, Spica has been the subject of many observational studies. In Hindu astronomy, Spica corresponds to the Nakshatra Chitrā. Consequently, the Chinese name for Spica is 角宿一 ( Jiǎo Sù yī, English: the First Star of Horn). In Chinese, 角宿 ( Jiǎo Xiù), meaning Horn (asterism), refers to an asterism consisting of Spica and ζ Virginis. Eta Boötis) Alarph, Arabic for 'the grape-gatherer' or 'gleaner', and Sumbalet ( Sombalet, Sembalet and variants), from Arabic سنبلة sunbulah "ear of grain". Other traditional names are Azimech / ˈ æ z ɪ m ɛ k/, from Arabic السماك الأعزل al-simāk al-ʼaʽzal 'the unarmed simāk (of unknown meaning, cf. Α Virginis ( Latinised to Alpha Virginis) is the system's Bayer designation. It was also anglicized as Virgin's Spike. The name is derived from the Latin spīca virginis "the virgin's ear of grain". It is now so entered in the IAU Catalog of Star Names. ![]() The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN which included Spica for this star. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. 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. The primary is a blue giant and a variable star of the Beta Cephei type. 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. Analysis of its parallax shows that it is located 250 ☑0 light-years from the Sun. It has the Bayer designation α Virginis, which is Latinised to Alpha Virginis and abbreviated Alpha Vir or α Vir. Spica is the brightest object in the constellation of Virgo and one of the 20 brightest stars in the night sky.
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