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Triangulum Galaxy

October 6, 2015

Our home galaxy, the Milky Way, is one of the giants of its galactic neighborhood, known as the Local Group. In fact, it’s second only to the Andromeda galaxy.

The third-largest member of the group is a stunner as well. Like its bigger cousins, M33 is a spiral — a disk of stars and gas, with hot young stars tracing out bright spiral arms. It’s roughly half as wide as the Milky Way, but it contains only about one-tenth as many stars.

The galaxy is giving birth to new stars in a hurry, though, because it contains a lot of gas and dust — the raw ingredients for making stars.

Much of that material is concentrated in a few large clumps. By far the biggest is NGC 604, one of the largest stellar nurseries in the entire Local Group. It spans about 1500 light-years, and contains tens of thousands of stars.

Those stars seem to have been born in two waves — one about 12 million years ago, and another about three million years ago. The more recent wave gave birth to a couple of hundred stars that are especially big and bright. Radiation from these stars causes the remaining gas around them to glow brightly, so NGC 604 is easily visible in just about any photograph of the galaxy.

And M33 is in the faint little constellation Triangulum, which is well up in the east by mid evening. The galaxy is visible through binoculars as a hazy smudge of light not far from the triangle of stars that gives the constellation its name.


Script by Damond Benningfield, Copyright 2015

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