Super-sharp images of Messier 83 reveal an oddity at its center
The NASA-ESA operated Hubble Space Telescope recently released images taken of the Messier 83 spiral galaxy, located a relatively short 15 million light years away. Also known as the “Southern Pinwheel Galaxy,” it sits within the constellation Hydra. Unlike most galaxies, it has a twist: At its core lies not one, but two black holes.
Being so close to Earth (the closest, actually), Messier 83 is one of the most observed galaxies in the universe. It’s a highly-visible member of a group of galaxies known as the Centaurus A/M83 Group. This group includes dusty Centaurus A and irregular NGC 5253 as members.
Spiral galaxies (like the milky way, Earth’s own galaxy) come in a range of types depending on their appearance and structure — for example, how tightly wound their arms are, and the characteristics of the central bulge. Messier 83 has a “bar” of stars slicing through its center, leading to its classification as a barred spiral. The Milky Way also belongs to this category. These bars act a like a funnel, guiding gas inwards towards the galaxy’s core. This gas is then used to form new stars and also to feed the galaxy’s central black hole, explaining why many barred spirals — including Messier 83 — have very active and spectacular central regions.
What sets M83 apart is that the black hole at its center isn’t exactly flying solo. Though not exactly two distinct black holes, Messier 83 has what’s known as a double nucleus, a supermassive black hole ringed by off-center discs of stars. Together, the unusual combination of the black hole and star discs give the illusion of a truly dual-core galaxy.
Not to be outdone, scientists have thus far recorded six supernova explosions in Messier 83, a figure matched or surpassed by only two other galaxies: Messier 61 (also six) and NGC 6946 (9). 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. They also found around 3,000 star clusters (literally: clouds or groups of stars), some of which are just 5 million years young.
Scientists plan to use the images to continue to guess the ages of the aforementioned star clusters, looking at things like the color and sharpness of the stars to estimate their ages.
Worth keeping in mind is that as impressive as Messier 83 looks, it’s just half the size of our Milky Way galaxy.
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