Akari Galaxy Image M101
M101 is a spiral galaxy twice the size of our own Galaxy, 170 000 light-years in diameter, near the tail of the Great Bear constellation. AKARI’s new observations reveal differing populations of stars spread across its spiral arms.
Using the AKARI space infrared telescope, astronomers have been able to find the warm dust heated by the birth of stars like our Sun in M101, and cooler dust heated by stars more like the present-day Sun.
The image shows the visible light (green), the far-ultraviolet light (cyan) from young stars, the warm dust (red) and the cooler dust (blue). This warm dust is mainly along the spiral arms, with hot spots along the galaxy's outer edge. These hot spots are giant star-forming regions, and it is unusual to find these on the edges of a galaxy.
Commenting on this image Dr Stephen Serjeant from The Open University said, "The evidence points to M101 having experienced a close encounter or near collision with a neighbour or companion galaxy, and it could be that it yanked material out of its neighbour which is now raining down on one side of galaxy and triggering this star formation."
Galaxies near and far from Akari - In Depth Article - from ESA