星团M35与NCG 2158

2021年05月09日

Star Clusters M35 and NGC 2158
Image Credit & Copyright: CFHT, Coelum, MegaCam, J.-C. Cuillandre (CFHT) & G. A. Anselmi (Coelum)

Explanation: Clusters of stars can be near or far, young or old, diffuse or compact. The featured image shows two quite contrasting open star clusters in the same field. M35, on the lower left, is relatively nearby at 2800 light years distant, relatively young at 150 million years old, and relatively diffuse, with about 2500 stars spread out over a volume 30 light years across. Bright blue stars frequently distinguish younger open clusters like M35. Contrastingly, NGC 2158, on the upper right, is four times more distant than M35, over 10 times older, and much more compact. NGC 2158’s bright blue stars have self-destructed, leaving cluster light to be dominated by older and yellower stars. In general, open star clusters are found in the plane of our Milky Way Galaxy, and contain anywhere from 100 to 10,000 stars — all of which formed at nearly the same time. Both open clusters M35 and NGC 2158 can be found together with a small telescope toward the constellation of the Twins (Gemini).

Tomorrow’s picture: beyond uluru

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星团M35与NCG 2158
影像提供与版权: CFHT, Coelum, MegaCam, J.-C. Cuillandre (CFHT) & G. A. Anselmi (Coelum)

说明: 星团与我们的距离可远可近，年龄可稚可老，结构可松可紧。这幅主题影像，呈现位在同一片星野里的2个高对比的疏散星团。左下角的M35，距离是相对邻近的2,800光年，年龄也是相对年轻的1亿5千万年，而且结构较松散，它的2,500多颗成员星，分布在30光年宽的区域内。像M35这种较年轻的疏散星团，明亮的泛蓝成员星是它显而易见的特征。左上角作为对比的NGC 2158，是个距离比M35要远上4倍，年龄大上10倍，也远为紧实的疏散星团。 NGC 2158里的明亮泛蓝恒星皆已爆炸死亡，只留下散发黄光的较老龄泛黄恒星。疏散星团通常出现在我们银河系的盘面附近，星团的恒星数介于100至10,000，而且这些成员星皆几乎同时诞生。位在双子座方向的M35和NGC 2158，是用小望远镜即可同时见到的天体。

明日的图片: beyond uluru