M95:带内环的旋涡星系
影像来源与版权:NASA, ESA, Hubble, ESO, Amateur Data; Processing & Copyright: Robert Gendler & Roberto Colombari

说明:为什么有些旋涡星系的中央有一个光环?首先,M95是一个庞大而美丽棒旋星系的距离较近的例子之一。在这幅由哈勃望远镜和数台地面望远镜拍摄的多张照片结合而成的特征影像中,可以看到由亮蓝色疏散星团勾勒出的蜿蜒旋臂、黑暗尘埃带、数十亿黯淡恒星的弥散辉光以及横跨星系中央的短棒状结构。然而,令许多天文学家感兴趣的是中央棒外、围绕星系中央核心的光环。虽然这个光环的长期稳定性仍然是一个研究课题,但观测结果表明,它目前的亮度因为恒星形成的短暂爆发而有些许增强。M95亦称为NGC 3351,其大小约为5万光年,距离我们约3千万光年远,可以使用小型望远镜朝着狮子座方向观测到它。
翻译:北京天文馆

M95: Spiral Galaxy with an Inner Ring
Image Credit: NASA, ESA, Hubble, ESO, Amateur Data; Processing & Copyright: Robert Gendler & Roberto Colombari

Explanation: Why do some spiral galaxies have a ring around the center? First and foremost, M95 is one of the closer examples of a big and beautiful barred spiral galaxy. Visible in the featured combination of images from Hubble and several ground based telescopes are sprawling spiral arms delineated by open clusters of bright blue stars, lanes of dark dust, the diffuse glow of billions of faint stars, and a short bar across the galaxy center. What intrigues many astronomers, however, is the circumnuclear ring around the galaxy center visible just outside the central bar. Although the long term stability of this ring remains a topic of research, observations indicate its present brightness is at least enhanced by transient bursts of star formation. M95, also known as NGC 3351, spans about 50,000 light-years, lies about 30 million light years away, and can be seen with a small telescope toward the constellation of the Lion (Leo).
Astronomy Picture of the Day 05/29/2019