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Epsilon Cassiopeiae (ε Cas, ε Cassiopeiae) is a star system in the constellation Cassiopeia. It has the traditional name Segin. With an apparent visual magnitude of 3.4,〔 this is one of the brightest stars in the constellation. It is located at a distance of around .〔 __FORCETOC__ ==Properties== ε Cassiopeiae is a giant star with a stellar classification of B3 III,〔 indicating that it has exhausted the hydrogen at its core and entered a later evolutionary stages of its lifetime. Cote ''et al.'' (2003) indicate that it displays the spectral properties of a Be star, even though it is not categorized as such.〔 The presence of emission lines in the spectrum indicates the presence of a circumstellar shell of gas that has been thrown off by the star.〔 The outer atmosphere has an effective temperature of ,〔 giving it the blue-white hue of a B-type star.〔 The distance to this star has been determined directly using parallax measurements, yielding a value of around .〔 The interferometer-measured angular diameter is 0.43 milliarcseconds.〔 At the estimated distance of this star, this yields a physical size of roughly 6 times the radius of the Sun.〔 Observation during the Hipparcos mission suggest that the star may undergo weak periodic variability. The amplitude of this variation is 0.0025 in magnitude with a frequency of 11.17797 times per day, or one cycle every 2.15 hours. The signal-to-noise ratio for this measured variation is 4.978.〔 Hipparcos measurements of the space velocity components for this star suggest that it is a member of the Cas-Tau group of co-moving stars, with a 93% likelihood. This group may be kinematically associated with the alpha Persei cluster, indicating that the Cas-Tau group, including Epsilon Cassiopeiae, may have been separated from the cluster through tidal interactions.〔 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「Epsilon Cassiopeiae」の詳細全文を読む スポンサード リンク
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