The Hydrogen Clouds of M33
Image Credit & Copyright:
Luca Fornaciari

Explanation: Gorgeous spiral galaxy M33 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. 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. To highlight the HII regions in this telescopic image, broadband data used to produce a color view of the galaxy were combined with narrowband data recorded through a hydrogen-alpha filter, transmitting the light of the strongest hydrogen emission line. Close-ups of cataloged HII regions appear in the sidebar insets. Use the individual reference number to find their location within the Triangulum Galaxy. For example, giant HII region NGC604 is identified in an inset on the right and appears at position number 15. That’s about 4 o’clock from galaxy center in this portrait of M33.

Tomorrow’s picture: ceci n’est pas une pipe

Luca Fornaciari

说明: 壮丽的螺旋星系M33看似拥有特别多的辉光氢气。距离约3百万光年远的M33,又名为三角星系,是本星系群的大成员之一。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最大型恒星形成区。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。为突显这幅望远镜影像里的HII区,上图整合了宽波段的彩色星系影像,与只容最明亮红光氢发射线透过的氢α滤镜窄波段影像数据。这幅影像边缘的嵌图,则是此星系内有编录号的HII区。从嵌图右上角的编号,可在三角星系里找到它们的位置。例如右缘嵌图15所呈现的天体,是位在编号15那个位置的庞大HII区NGC604。在这幅M33影像里,大约是位在星系中心4点钟的方向。

明日的图片: ceci n’est pas une pipe