January 10, 2014
ESA Releases Hubble Image Of Messier 83, A Galaxy With Two Hearts
April Flowers for redOrbit.com - Your Universe Online
Messier 83, which is one of the largest and closest barred spiral galaxies to us, has hosted a large number of supernova explosions, and is thought to have a double nucleus at its core. The image was released this week at the 223rd meeting of the American Astrophysical Society.
One of the most conspicuous galaxies of its type in our skies, Messier 83 is not one to blend into the background. Located approximately 15 million light-years away in the constellation of Hydra (the Sea Serpent), Messier 83 is a prominent member of a group of galaxies known as the Centaurus A/M83 Group. This group includes dusty Centaurus A (heic1110) and irregular NGC 5253 (potw1248a) as members.
Depending on their appearance and structure -- for example, differences in how tightly wound the arms are, and the characteristics of the central bulge -- spiral galaxies come in a wide range of types. Messier 83 is classified as a barred spiral galaxy due to the “bar” of stars slicing through its center. Our own galaxy, the Milky Way, belongs to this same category.
Scientists believe that these bars act a bit like funnels, channeling gas inwards toward the galaxy’s center. The gas then feeds the galaxy’s black hole -- explaining why many barred spirals, including Messier 83, have very active and luminous central regions. The gas is also used to form new stars.
Astronomers found Messier 83’s center mysterious and unusual, however, because the supermassive black hole at its center is not alone. Messier 83 displays a phenomenon known as a double nucleus. The Andromeda Galaxy, which is the nearest spiral galaxy to us, also has a double nucleus. A double nucleus does not necessarily mean that Messier 83 has two central black holes, but rather that its single supermassive black hole may be ringed by a lopsided disc of stars. These stars orbit around the black hole and create the appearance of a dual core.
Messier 83 has also played host to quite a few supernova explosions. So far, astronomers have observed six: SN 1923A, SN 1945B, SN 1950B, SN 1957D, SN 1968L, and SN 1983N. Only two other galaxies match this number: Messier 61 (potw1324a) which also has six, and NGC 6946 (opo9910e), which tops the list with nine.
Almost 300 supernova remnants have been found within Messier 83 as well. These older, leftover materials from exploded stars were detected using the data that make up the new image. Researchers are using these observations to study the life cycle of stars. In addition to the remnants, approximately 3,000 star clusters, including some which are very young at less than 5 million years old, have been identified in Messier 83.
The newly released image is a mosaic created using observations from Hubble’s Wide Field Camera 3. The galaxy is depicted in full, with dark dust lanes, fiery red patches of gas, and bright blue patches of recent star formation speckled across the spiraling arms. Despite the look of it, Messier 83 is just under half the size of the Milky Way.