毕宿一: 有行星的恒星

毕宿一: 有行星的恒星

Epsilon Tauri: Star with Planet
Image Credit & Copyright: Reg Pratt

Explanation: Epsilon Tauri lies 146 light-years away. A K-type red giant star, epsilon Tau is cooler than the Sun, but with about 13 times the solar radius it has nearly 100 times the solar luminosity. A member of the Hyades open star cluster the giant star is known by the proper name Ain, and along with brighter giant star Aldebaran, forms the eyes of Taurus the Bull. Surrounded by dusty, dark clouds in Taurus, epsilon Tau is also known to have a planet. Discovered by radial velocity measurements in 2006, Epsilon Tauri b is a gas giant planet larger than Jupiter with an orbital period of 1.6 years. And though the exoplanet can’t be seen directly, on a dark night its parent star epsilon Tauri is easily visible to the unaided eye.

Tomorrow’s picture: light-weekend

毕宿一: 有行星的恒星
影像提供与版权: Reg Pratt

说明: 毕宿一距离我们146光年。毕宿一是K型的红巨星，温度比太阳低，半径约为太阳的13倍，光度则几乎是太阳的100倍。这颗专有名为艾因（Ain）的巨星，是毕宿疏散星团的成员之一，它与更明亮的巨星毕宿五构成金牛的眼睛。周围环绕着金牛座尘埃云的毕宿一，拥有一颗行星。 2006年用径向速度量测法所发现的这颗行星毕宿一b，是一颗比木星大、轨道周期为1.6年的气态巨行星。虽然不能直接看到这颗系外行星，但在幽暗的夜晚，用肉眼可轻易见到它的母星毕宿一。

明日的图片: light-weekend