Red Supergiant Stars

Red Supergiants

红超巨星

A star of 15 solar masses exhausts its hydrogen in about one-thousandth the lifetime of our sun. It proceeds through the red giant phase, but when it reaches the triple-alpha process of nuclear fusion, it continues to burn for a time and expands to an even larger volume. The much brighter, but still reddened star is called a red supergiant. Betelgeuse, at the shoulder of Orion, is the best-known example. Absolute luminosities may reach -10 magnitude compared to +5 for our sun.

一个15倍太阳质量的恒星耗尽氢的时间大约是太阳寿命的千分之一。它进入红巨星阶段，但当它达到三 alpha 过程的核聚变时，它继续燃烧一段时间，并膨胀到更大的体积。虽然亮度更高，但仍然呈红色的恒星被称为红超巨星。猎户座的肩部的参宿四就是最著名的例子。绝对光度可能达到比太阳的+5等亮度-10等。

Some of these supergiants are unstable and form the very important Cepheid variables. In their final stages, supergiants may explode into supernovae. The collapse of these massive stars may produce a neutron star or a black hole.

这些超巨星中有一些是不稳定的，会形成非常重要的造父变星。在它们的最后阶段，超巨星可能会爆发成超新星。这些大质量恒星的坍缩可能会产生中子星或黑洞。

Betelgeuse

参宿四

red supergiant

Sun

If it were positioned at the center of our sun, its radius would extend out past the radius of Mars, approaching 2 astronomical units! Most stars on the main sequence have about the same size as the sun. It has a surface temperature of about 3000 K as determined from its blackbody radiation curve. Betelgeuse is about 310 light years away from the Earth. Its celestial coordinates are RA=5 h 52 m , dec=7° 24' .

如果它位于太阳中心，其半径将延伸到火星轨道之外，接近2个天文单位！大多数主序星的大小与太阳相当。它的表面温度约为3000 K，这是根据其黑体辐射曲线确定的。参宿四距离地球约310光年。其天球坐标为RA=5小时52分，dec=7°24′。

参宿四是一颗典型的红超巨星。它位于猎户座的肩部。它是北美洲观测者所见的冬季三角形的一部分。参宿四的光度大约是太阳的10000倍，其半径计算为太阳的约370倍。

Arcturus

天琴座α星

Arcturus is a red giant star in the Northern Hemisphere of Earth's sky. It is the brightest star in the constellation of Bootes, the fourth-brightest in the night sky, and the brightest in the northern celestial hemisphere. Together with Spica and Regulus, Arcturus is part of the Spring Triangle and, by extension, also of the Great Diamond along with the star Cor Caroli. It is positioned almost at the north galactic pole of the Milky Way.

Arcturus 是一颗位于地球天空北半球的红巨星。它是室女座中最亮的恒星，是夜空中第四亮的天体，也是北天赤道带最亮的天体。与天琴座的天琴座星（Spica）和天琴座的天琴座星（Regulus）一起，Arcturus 是春三角的一部分，进而也属于与天琴座的天琴座星（Cor Caroli）一起构成的巨钻石。它几乎位于银河系的北天极。

Relatively close at 36.7 light-years from the Sun, Arcturus is a red giant of spectral type K0III - an aging star around 7.1 billion years old that has used up its core hydrogen and moved off the main sequence. It is 1.08±0.06 times as massive as the Sun, but has expanded to 25.4±0.2 times its diameter and is around 170 times as luminous.

距离太阳约36.7光年，Arcturus是一颗红巨星，光谱类型为K0III。这颗恒星年龄约为71亿年，已耗尽核心的氢并离开主序带。它的质量是太阳的1.08±0.06倍，但其直径已膨胀至太阳的25.4±0.2倍，其光度约为太阳的170倍。