|
Delta Cygni (δ Cygni, δ Cyg) is the third-magnitude star in the constellation Cygnus. It will be the "North Star" for at least four centuries around 11,250. This star belonged to the Arabic asterism ''al-Fawāris'' (), meaning "the Riders" in indigenous Arabic., together with ζ, ε, and γ Cyg, the transverse of the Northern Cross. In Chinese, (), meaning ''Celestial Ford'', refers to an asterism consisting of δ Cygni, γ Cygni, 30 Cygni, α Cygni, ν Cygni, τ Cygni, υ Cygni, ζ Cygni and ε Cygni.〔 ''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, δ Cygni itself is known as (, (英語:the Second Star of Celestial Ford).)〔 (AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 4 日 )〕 == Features == Delta Cygni is a triple star; the system lies at a distance of about 170 light years and consists of two stars quite close together and one much farther out. This sort of common configuration lends stability. The bright naked-eye star is a blue-white giant of spectral class B9,〔 with a temperature of 9,800 kelvins. It is nearing the end of its main-sequence life stage with a luminosity 180 times that of the Sun, a radius of 4.7 solar radii, and a mass approximately 3.15 solar masses. Like many hot stars, it spins rapidly, at least 135 kilometers per second at the equator, about 60 times that of the Sun. Its close companion is a yellow-white class F of the sixth magnitude (6.33) with a luminosity about 6 times that of the sun, and a mass about 1.5 times that of the sun. The much more distant third companion is an orange (class K) twelfth magnitude star, being only 38% as luminous as the sun, and only 70% as massive as the sun. As seen from Earth, the entire triple star system of Delta Cygni shines at a combined apparent magnitude of 2.86. 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「Delta Cygni」の詳細全文を読む スポンサード リンク
|