哈勃观测到一个活跃的恒星形成星系

This NASA/ESA Hubble Space Telescope image features IC 3476, a dwarf galaxy that lies about 54 million light-years from Earth in the constellation Coma Berenices. While this image does not look very dramatic – we might say it looks almost serene – the actual physical events taking place in IC 3476 are highly energetic. In fact, the little galaxy is undergoing a process called ram pressure stripping that is driving unusually high levels of star formation in regions of the galaxy.

The gas and dust that permeates space exerts pressure on a galaxy as it moves. This resistance, called ram pressure, can strip a galaxy of its star-forming gas and dust, reducing or even stopping the creation of new stars. However, ram pressure can also compress gas in other parts of the galaxy, which can boost star formation. This may be happening in IC 3476. The galaxy appears to have absolutely no star formation along its edges, which bear the brunt of the ram pressure stripping, but star formation rates deeper within the galaxy are noticeably above average.

Text credit: European Space Agency (ESA)

这张NASA/ESA哈勃太空望远镜拍摄的图像显示的是IC 3476，这是一个矮星系，距离地球约5,400万光年，位于后发座。虽然这张图片看起来并不十分引人注目——我们可以说它看起来几乎很平静–但在IC 3476星系中发生的实际物理事件非常活跃。事实上，这个小星系正在经历一个叫做冲压剥离的过程，这个过程正在星系的某些区域推动着异常高水平的恒星形成。

弥漫在太空中的气体和尘埃在星系运动时对其施加压力。这种阻力被称为冲压，它可以剥离星系中形成恒星的气体和尘埃，减少甚至停止新恒星的产生。然而，冲压也可以压缩星系其他部分的气体，从而促进恒星的形成。这可能发生在IC 3476中。这个星系的边缘似乎完全没有恒星形成，这些边缘受到了冲压的影响，但星系深处的恒星形成率明显高于平均水平。

影像来源：European Space Agency (ESA)