Two nearby galaxies peek out through the dust

The entire universe in blog form
March 9 2010 7:26 AM

Two nearby galaxies peek out through the dust

NASA's Wide-field Infrared Survey Explorer, or WISE, only launched a couple of months ago, and has already done spectacular work. Gulping down huge tracts of sky every day, it has already discovered over 2000 asteroids -- not seen, but actually discovered -- including several that pass near the Earth (none on track to hit us, happily). It's discovered four comets, too, and by the end of the mission in a few months will see far more.

But since it's a survey instrument, and it sees in the far infrared, the views it gets are nothing short of spectacular! Like this one:

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

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WISE_Maffei1_2

[Click to embiggen, or grab this ginormous 11,000x4000 TIF].

There is a lot to see here! First, the colors: all of this is far infrared, with blue being the IR wavelengths of 3.4 and 4.6 microns combined (5 and 6.5 times the wavelength the human eye sees), green is 12 microns, and red 22. Green is dominated by warm dust and big organic molecules called polycyclic aromatic hydrocarbons.

The glowing gassy stuff is part of the Heart Nebula, which I've posted about before (guess what date). But take a look a bit to the left of all that gas, and look much, much farther in distance...

WISE_Maffei_zoom

Those are two galaxies, called Maffei 1 and 2. Both are actually quite close to the Milky Way, only about 10 million light years away. They're big galaxies, and really should be among the brightest galaxies in the sky. Yet chances are you've never heard of them! That's because this area of the sky is loaded with dust in our galaxy, which absorbs visible light. Another incredibly beautiful galaxy, IC 342, is also part of that group, but is hard to see in visible light as well.

Maffei 1 is right and below center, and Maffei 2 is the barred spiral one above it. For comparison, this image here is about twice the diameter of the Moon on the sky. WISE has a huge field of view, so it doesn't get high-res images of galaxies, but it more than makes up for it in breadth and depth. Observations like this will help astronomers map the dusty content of nearby galaxies, and even get a handle on how much dust is in much more distant galaxies, though the maps won't be quite as detailed. Still, more information is always good, and getting to study galaxies -- and nebulae, and planets, and comets, and asteroids, and and and -- in the far infrared will help our understanding of all these objects far better.

As an aside, I learned of this image on my pal Amy Mainzer's WISE blog. She's a bigwig with WISE, and when she has time away from doing nonstop firehose science she writes up fun stuff about this new and extremely cool spacecraft. That's definitely one you want to drop into your RSS feed reader!