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61 Virginis (abbreviated 61 Vir) is a G-type main-sequence star (G7V) slightly less massive than the Sun (which is G2V), located about 27.9 light-years away in the constellation of Virgo. The composition of this star is nearly identical to the Sun. 61 Virginis (G7V) is the first well-established main-sequence star very similar to the Sun with a potential Super-Earth,〔 though COROT-7 (a borderline orange dwarf) is arguably the first. ==Description== 61 Virginis is a fifth-magnitude G-type main-sequence star with a stellar classification of G7 V.〔 It is faint but visible to the naked eye south and east of the bright star Spica in the zodiac constellation of Virgo. The designation 61 Virginis originated in the star catalogue of English astronomer John Flamsteed, as part of his ''Historia Coelestis Britannica''. An 1835 account of Flamsteed's work by English astronomer Francis Baily noted that the star showed a proper motion.〔 This made the star of interest for parallax studies, and by 1950 a mean annual value of 0.006″ was obtained.〔 The present day result, obtained with data from the Hipparcos satellite, gives a parallax of 116.89 mas,〔 which corresponds to a physical separation of 27.9 light years from the Sun. This star is similar in physical properties to the Sun, with around 95%〔 of the Sun's mass, 98%〔 of the radius, and 85%〔 of the Luminosity. The abundance of elements is also similar to the Sun, with the star having an estimated 95%〔 of the Sun's proportion of elements other than hydrogen and helium. It is older than the Sun at around 6.1–6.6〔 billion years of age, and is spinning with a leisurely projected rotational velocity of 4〔 km/s at the equator. On average, there is only a low level of activity in the stellar chromosphere〔 and it is a candidate for being in a Maunder minimum state.〔 But the star was suspected as variable in 1988,〔 and a burst of activity was observed between Julian days ()54800 (29 November 2008) and 55220 (23 January 2010).〔 The space velocity components of this star are U = –37.9, V = –35.3 and W = –24.7 km/s. 61 Vir is orbiting through the Milky Way galaxy at a distance of 6.9 kpc from the core, with an eccentricity of 0.15. It is believed to be a member of the disk population.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「61 Virginis」の詳細全文を読む スポンサード リンク
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