Saturday, Mar 8, 2025

NGC 3184 in Ursa Major is surrounded by brilliantly shining stars that seem to escort this beautifully spot-on galaxy through space (of course, in reality, the stars and the galaxy are separated by millions of light-years). NGC 3184 contains many HII regions where new stars are forming. To make these visible, I additionally captured over five hours of H-alpha data, though I blended it in rather sparingly. NGC 3184, the Little Pinwheel Galaxy, is an unbarred spiral galaxy located approximately 40 million light-years away in the constellation Ursa Major. Its name comes from its resemblance to the Pinwheel Galaxy. It was discovered on March 18, 1787, by the German-British astronomer William Herschel. The galaxy has two HII regions, known as NGC 3180 and NGC 3181. NGC 3184 has a high concentration of heavy elements. The blue color of its spiral arms is mainly due to a relatively small number of bright young blue stars. The luminous stars that highlight the arms were formed in massive density waves that circle the center. The galaxy is estimated to be 26 million light-years away from our Milky Way and has a diameter of 60,000 light-years. The bright star on the left is μ Ursae Majoris, officially named "Tania Australis," a binary star with an apparent visual magnitude of +3.06, located approximately 230 light-years away from us.