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Beta Canum Venaticorum (β CVn, β Canum Venaticorum) is a G-type main-sequence star in the northern constellation Canes Venatici. At an apparent visual magnitude of 4.26,〔 it is the second-brightest star in this relatively faint constellation. Based upon an annual parallax shift of 118.49 mas,〔 this star is distant from the Earth. Along with the brighter star Cor Caroli, the pair form the "southern dog" in this constellation that represents hunting dogs. The name Chara was originally applied to the "southern dog", but it later became used specifically to refer to Beta Canum Venaticorum. Chara ''(χαρά)'' means ''Joy'' in Greek.〔 In Chinese, (), meaning ''Imperial Guards'', refers to an asterism consisting of β Canum Venaticorum, α Canum Venaticorum, 10 Canum Venaticorum, 6 Canum Venaticorum, 2 Canum Venaticorum, and 67 Ursae Majoris.〔 ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.〕 Consequently, β Canum Venaticorum itself is known as (, (英語:the Fourth Star of Imperial Guards).)〔 (香港太空館 - 研究資源 - 亮星中英對照表 ), Hong Kong Space Museum. Accessed on line November 23, 2010.〕 ==Observations== At apparent magnitude 4.26, Beta Canum Venaticorum is the second brightest star in the constellation. It has a stellar classification of G0 V, and so is a G-type main sequence star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.〔 The spectrum of this star shows a very weak emission line of singly ionized calcium (Ca II) from the chromosphere, making it a useful reference star for a reference spectrum to compare with other stars in a similar spectral category.〔 (The Ca-II emission lines are readily accessible and can be used to measure the level of activity in a star's chromosphere.) β CVn is considered to be slightly metal-poor,〔 which means it has a somewhat lower portion of elements heavier than helium when compared to the Sun. In terms of mass, age and evolutionary status, however, this star is very similar to the Sun.〔 As a result, it has been called a solar analog. It is about 3% more massive than the Sun,〔 with a radius 12% larger than the Sun's and 15% greater luminosity.〔 The components of this star's space velocity are = .〔 In the past it was suggested that it may be a spectroscopic binary. However, further analysis of the data does not seem to bear that out.〔 In addition, a 2005 search for a brown dwarf in orbit around this star failed to discover any such companion, at least down to the sensitivity limit of the instrument used.〔 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「Beta Canum Venaticorum」の詳細全文を読む スポンサード リンク
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