哈勃太空望远镜更近距离地观察了“未死”的邻居


   2019-09-20 丨 NASA·每日一图 丨 nasachina  丨  No Comment 丨  232

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Many of the best-loved galaxies in the cosmos are remarkably large, close, massive, bright, or beautiful, often with an unusual or intriguing structure or history. However, it takes all kinds to make a universe — as demonstrated by this Hubble image of Messier 110.

Messier 110 may not look like much, but it is a fascinating near neighbor of our home galaxy, and an unusual example of its type. It is a member of the Local Group, a gathering of galaxies comprising the Milky Way and a number of the galaxies closest to it. Specifically, Messier 110 is one of the many satellite galaxies encircling the Andromeda galaxy, the nearest major galaxy to our own, and is classified as a dwarf elliptical galaxy, meaning that it has a smooth and almost featureless structure. Elliptical galaxies lack arms and notable pockets of star formation — both characteristic features of spiral galaxies. Dwarf ellipticals are quite common in groups and clusters of galaxies, and are often satellites of larger galaxies.

Because they lack stellar nurseries and contain mostly old stars, elliptical galaxies are often considered “dead” when compared to their spiral relatives. However, astronomers have spotted signs of a population of young, blue stars at the center of Messier 110 — hinting that it may not be so “dead” after all.

Messier 110 is featured in Hubble’s Messier catalog, which includes some of the most fascinating celestial objects that can be observed from Earth’s Northern Hemisphere. See the NASA-processed image and other Messier objects at: https://www.nasa.gov/content/goddard/hubble-s-messier-catalog.

Text credit: ESA (European Space Agency)
Image credit: ESA/Hubble & NASA, L. Ferrarese et al.

宇宙中许多最受欢迎的星系都非常大、非常近、非常巨大、非常明亮或非常美丽,它们的结构或历史通常都不寻常或引人入胜。然而,宇宙是由各种各样的物质构成的——这张由哈勃拍摄的Messier 110的照片就证明了这一点。

Messier 110可能看起来不太像,但它是我们的母星系的一个迷人的近邻,也是它类型的一个不寻常的例子。它是一个局部星系群的成员,这个星系群由银河系和一些离它最近的星系组成。具体来说,Messier 110是环绕仙女座星系的众多卫星星系之一,仙女座星系是离我们最近的主要星系,被归类为矮椭圆星系,这意味着它有一个光滑的几乎没有特征的结构。椭圆星系缺少臂和明显的恒星形成区——这两个特征都是螺旋星系的特征。矮椭圆星系在星系群和星系团中很常见,通常是较大星系的卫星。

由于椭圆星系缺乏恒星孕育区,而且大部分都是古老的恒星,所以与它们的螺旋星系相比,椭圆星系通常被认为是“死亡的”。然而,天文学家们在Messier 110的中心发现了年轻的蓝色恒星群的迹象,这意味着它可能根本没有那么“死亡”。

Messier 110被收录在哈勃望远镜的梅西埃目录中,其中包括了一些可以从地球北半球观测到的最迷人的天体。美国航天局处理的图像和其他Messier物体:https://www.nasa.gov/content/goddard/hubble-s-messier-catalog

资料来源:ESA (European Space Agency)
图片来源: ESA/Hubble & NASA, L. Ferrarese et al.

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