辇道增七

2022年2月24日

Beautiful Albireo AB
Image Credit & Copyright: Robert Eder

Explanation: Beta Cygni is a single bright star to the naked eye. About 420 light-years away it marks the foot of the Northern Cross, famous asterism in the constellation Cygnus. But a view through the eyepiece of a small telescope will transform it into a beautiful double star, a treasure of the night sky in blue and gold. Beta Cygni is also known as Albireo, designated Albireo AB to indicate its two bright component stars. Their visually striking color difference is illustrated in this telescopic snapshot, along with their associated visible spectrum of starlight shown in insets to the right. Albireo A, top inset, shows the spectrum of a K-type giant star, cooler than the Sun and emitting most of its energy at yellow and red wavelengths. Below, Albireo B has the spectrum of a main sequence star much hotter than the Sun, emitting more energy in blue and violet. Albireo A is known to be a binary star, two stars together orbiting a common center of mass, though the two stars are too close together to be seen separately with a small telescope. Well-separated Albireo A and B most likely represent an optical double star and not a physical binary system because the two components have clearly different measured motions through space.

Tomorrow’s picture: mars with moxie

辇道增七
影像提供与版权: Robert Eder

说明: 在人类的肉眼里，天鹅β（辇道增七）看起来是单颗亮星。距离约420光年远的这颗亮星，是标记著名天鹅座北十字星官底部的恒星。不过，如果透过小望远镜的目镜观看，它会分裂成为美丽的双星，一对水蓝与金黄的夜空珍宝。天鹅β的专名为Albireo，故常用Albireo AB来称呼这对双星的二颗明亮成员。在上图左侧的望远镜影像里，它们色泽上的差异即清楚可见，而右侧的嵌图则呈现它们星光的可见光谱。上方嵌图的光谱显示，辇道增七A是一颗温度比太阳低的K型巨星，最强烈的辐射出现在黄光与红光波段。其下的辇道增七B光谱显示，它是一颗远比太阳高温的主序星，在蓝光与紫外光波段发出最多辐射。辇道增七A本身是个双星系统，其成员星旋绕共同的质量中心运动，不过它们靠彼此太近，小望远镜并无法分解。而可清楚分解的辇道增七A与辇道增七B，在空间的各别运动明确有别，因此极可能只是光学双星，而非真正的物理双星系统。 （Beta Cygni = Albireo 辇道增七、天鹅[座]β[星]）

明日的图片: mars with moxie

[词汇学习]
中文丨Chinese Pinyin丨Cantonese Pinyin丨English

• 目镜

Mùjìng丨muk6 geng3丨eyepiece

• 辇道增七

niǎn dào zēng qī丨lin5 dou6 zang1 cat1丨Beta Cygni

• 北十字星

běi shízì xīng丨bak1 sap6 zi6 sing1丨the Northern Cross

• 星群

xīng qún丨sing1 kwan4丨asterism

• 天鹅座

tiān’é zuò丨tin1 ngo4 zo6丨Cygnus

• 双星

shuāngxīng丨soeng1 sing1丨binary stars

• 快照

kuàizhào丨faai3 ziu3丨snapshot

• 主序带

zhǔ xù dài丨zyu2 zeoi6 daai3丨Main Sequence

• K型巨星

K xíng jùxīng丨K-ying4-geui6-sing1丨K-type giant star

• 共同质心

gòngtóng zhìxīn丨gung6 tung4 zat1 sam1丨common center of mass

• 光谱

guāngpǔ丨gwong1 pou2丨spectrum

• 双星系统

shuāngxīng xìtǒng丨soeng1 sing1 hai6 tung2丨a binary system

*粤语拼音采用「香港语言学学会粤语拼音」方案。