Bode’s Galaxy – a grand-design spiral galaxy
Bode’s Galaxy (M81 or NGC 3031) is a grand-design spiral galaxy, some 11.8 million light-years away in the constellation Ursa Major. Its spiral arms and a number of sinuous dust lanes wind all the way down into the nucleus. M81 has many star formation regions, at least 32 Cepheid variables and an active galactic nucleus. The percentage of dark matter is estimated to be lower than average.
The central bulge is significantly larger than the Milky Way’s bulge. A supermassive black hole of 70 million solar masses resides at its center. This black hole is about 15 times the mass of the Milky Way’s black hole. Previous research shows that the size of the central black hole in a galaxy is proportional to the mass of a galaxy’s bulge.
Most of the emission at infrared wavelengths originates from interstellar dust which is found primarily within the galaxy’s spiral arms, and is associated with star formation regions. The general explanation is that the hot, short-lived blue stars that are found within star formation regions are very effective at heating the dust and hence enhancing the infrared dust emission from these regions.
Image Credit: NASA / ESA / AAN