"Baby Boom" galaxy cranks out cranky booming babies

By Phil Plait | July 10, 2008 4:01 pm

Before I get started, let me just preen a moment and say how much I loved writing that title.

But what’s it about? A rather non-descript galaxy was seen by Hubble and the Japanese Subaru telescope. It appeared with a lot of other galaxies in the field, and in optical light was no big deal. But then NASA’s Spitzer Space Telescope, and the James Clerk Maxwell telescope in Hawaii — both sensitive to infrared light — took a look, and bang!

Or more properly, boom! Check this out:

Spitzer image of baby boom galaxy

That’s no Peter Max painting, that’s a composite of visible light (green and blue) and infrared light (red) of this galaxy. It doesn’t have a real name, but astronomers have nicknamed it the Baby Boom galaxy. Why? Because it’s cranking out stars at a rate 400 times that of our own Milky Way galaxy.

Yegads. That’s a lot of stars. In fact, it’s spewing them out so quickly that it could grow in size to be a massive galaxy like ours in about 50 million years. It took billions of years for us to get as beefy as we are.

We know the star formation rate by examining the infrared light from the galaxy. When stars are born, they create a lot of dust. This dust gets heated by the UV light booming out from the newly born stars, too, which heats the dust, making it emit infrared. So by knowing how much IR the galaxy emits, you can estimate how many stars are being born.

Stars are popping out of this galaxy like clowns from a little car at the circus.

This would be pretty unusual for any galaxy, but what makes this weirder is that this puppy is 12.3 billion light years away, meaning we’re seeing it when the Universe was only a little over 1.4 billion years old. That means this galaxy is pretty young, and so it’s very odd to see it being so fruitful and multiplying. Normally, galaxies get big by eating other partially or fully-formed galaxies. Not this one though. It’s self-made.

My guess is that it’s an exception, and something pretty unusual is going on with it. Most galaxies do in fact grow by eating, and this one is either suffering an unusual number of collisions — so its gas clouds collide and form stars very rapidly — or some other oddness is making it so eager to churn out stars. I don’t think this will affect normal models of galaxy formation much… unless we find lots more like it. But it will certainly provide clues on how galaxies behave in the early Universe, which can otherwise be a difficult thing to observe.

CATEGORIZED UNDER: Astronomy, NASA, Pretty pictures, Science

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