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Home / Science / Poor Astronomy | A little splendor for you, with the spiral galaxy M61

Poor Astronomy | A little splendor for you, with the spiral galaxy M61



There are days – and for me it's almost every day – when we can all take a spectacular shot of a great spiral galaxy.

Is today such a day for you? Then I like to help.

But first a brief description …

M61 is an almost frontal spiral galaxy that is about 52 million light-years away. It's one of a few thousand galaxies that reside in the Virgo Cluster, the galaxy's closest galaxy cluster (in fact, the local group, our own small neighborhood of galaxies, and the Virgo Cluster are all part of much of the larger Virgo galaxies Supercluster, which itself is part of the Laniakea supercluster). These galaxies are so close that one night in May, decent binoculars show a dozen or more of them when you are in a dark, moonless place. So, when you look at the Hubble Space Telescope and Very Large Telescope on it, what you get is detail on a stunning level. Please refer!

This image is a compilation of Hubble and VLT observations (and some amateur images to fill in the gaps) created by the talents of astrophotographers Robert Gendler and Roberto Colombari. The spiral structure is pretty obvious, with massive, bright blue stars that track the arms and long tracks of opaque dust that intertwine them.

The central part of this galaxy is really interesting. The spiral goes to the middle, which is unusual. There is also a beam, a yellowish-red tic-tac-shaped structure that surrounds the core (almost vertical but slightly inclined in a clockwise direction) and contains older stars. Such bars are common in disc galaxies. The Milky Way also has a big one.

In the middle you can see a bluish mini spiral; In the middle of the galaxy is a super star cluster, a huge collection of newborn stars. Many of these stars are massive and emit visible light as well as ultraviolet, glowing gas. Remember, one second …

Also in the middle is a circular spot of light. Here is the supermassive black hole of M61

, one with a mass of about 5 million solar masses. That's pretty poor, as central black holes go; Most galaxies are much more massive. It is about the same mass as in the middle of the Milky Way, and in fact both galaxies are about the same diameter (about 100,000 light-years in diameter). So we're pretty much alike.

Only that M61's Black Hole is actively feeding on material! When a black hole like this picks up matter, it stacks up in a disk, and this matter gets incredibly hot and glows over the electromagnetic spectrum. We call galaxies like this active galaxy, and M61 is an example. But it is weak; The black hole is not a sloppy eater, so the light it emits is relatively weak.

In fact, the ultraviolet light that comes out of the nucleus is only partially due to the black hole, perhaps only a sixth of it or so. The rest comes from this super star cluster! That's pretty neat. Some active galaxies have nuclei that are so bright from the hot matter around the black hole that they glow intensely, the strongest and brightest objects in the entire universe! But in this case, M61's central monster is outshone by stars. That's unexpected, which is always fun.

If I read on M61, find these pictures and write about them, I would like to see it for myself! Unfortunately, it is far too deep in the West at the moment when the sun is low enough. it starts around the time when it gets dark. I've missed my shot this year (unless I want to get up in a couple of months before sunrise to try, which is … unlikely). But when spring comes next year, I can get the riflescope out and try it out. These pictures are incredible and the science is incredible. But getting these photons traveling after more than 50 million years … that literally brings them home.


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