Hydrogen Clouds of M33
Image Credit & Copyright:
Reinhold Wittich

Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies a mere 3 million light-years away. The galaxy’s central 30,000 light-years or so are shown in this sharp galaxy portrait. The portrait features M33’s reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33’s giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. In this image, broadband data were combined with narrowband data recorded through a hydrogen-alpha filter. That filter transmits the light of the strongest visible hydrogen emission line.

Tomorrow’s picture: ring around the Sun

Reinhold Wittich

说明: 壮丽的螺旋星系M33看似拥有特别多会散发辉光的氢气。距离约3百万光年远的M33,又名为三角大星系,是本星系群的大成员之一。这幅清晰的星系影像,呈现了此星系中心约30,000光年的区域。影像的主题则是M33里,称为HII区的泛红电离氢气云。这些散布在M33蜿蜒松散螺旋臂上的庞大HII区,是现知会产生大质量短命恒星的大型恒星形成区。来自这些明亮大质量恒星的强烈紫外辐射,电离周围的氢气,让它们发出特征性的泛红辉光。上图整合了宽波段数据,以及只透过最明亮泛红氢发射线的氢α窄波段滤镜数据。

明日的图片: ring around the Sun