Astronomy Picture Of The Day Explore the cosmos Every day, a new image or photograph of the universe is presented. A brief explanation by an astronomer is included. 2021 September 30
Hydrogen Clouds of M33
Image Credit & Copyright: Luca Fornaciari
Explanation: The beautiful spiral galaxy M33 appears to contain more glowing hydrogen gas than it should. M33, a prominent member of the local galaxy group, is also known by the Triangulum Galaxy. It lies just 3 million light years away. M33's giant HII areas, which are spread along loose spiral arms and wind towards the core, are some of the most important known stellar nurseries. They are sites of the formation short-lived, but extremely massive stars. The characteristic red glow is caused by intense ultraviolet radiation from the massive, luminous stars. Broadband data was used to highlight the HII areas in this telescopic view. This was combined with narrowband data captured through a hydrogen alpha filter. The light from the strongest hydrogen emission line is transmitted. Sidebar insets show close-ups of the HII regions. To locate them within the Triangulum Galaxy, use the individual reference numbers. Inset to the right shows NGC604, the giant HII region NGC604 and is located at position 15. This is approximately 4 o'clock away from the galaxy center in this M33 portrait.
