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SYFY WIRE Bad Astronomy

Rudolph the Red-Nosed Nebula

By Phil Plait
Barnard 3, a shell of gas and dust as seen in the far infrared by WISE. Credit: NASA/JPL-Caltech/WISE Team

About 800 light years from Earth, in the direction of the constellation of Perseus, there is a vast, sprawling complex of gas and thick dust. Called the Perseus molecular cloud complex, it's 100 light years long and has enough material in it to make tens of thousands of stars just like the Sun.

And just next it, and I mean literally abutting up against it, is another, if smaller, cloud. It has several names, including Barnard 3, CPS 5, and G159.6-18.5. It’s about 20 light years across —still respectable! — and when it was imaged by NASA’s Wide-field Infrared Survey Explorer, it really put on a show:

Barnard 3, a shell of gas and dust as seen in the far infrared by WISE. Credit: NASA/JPL-Caltech/WISE Team

Oh, I love this shot. Funny, though: In the press release for the image, it was said to look like a Christmas wreath. While holiday-appropriate, I think they missed a better call: It's Rudolph the Red-Nosed Reindeer!

You can see the two ears/antlers at the top and left, two eyes in the outline of the face, and hello, a bright red nose.

OK, it's not really a colossal genetically mutated caribou 20 quadrillion kilometers across. But in reality it's actually cooler.

Many clouds of gas and dust are a bit amorphous. But sometimes outside forces carve them into recognizable shapes… and sometimes inside forces do too. In this case, at the very center (in the center of that red cloud in fact) lies the star HD 278942, a mammoth blue beast with at least 20 times the mass of the Sun. It blasts out radiation, warming the gas around it. It also has a fierce wind of subatomic particles coming from it that may be responsible for slamming into the material around it and compressing it into that ring.

The colors you see in the image aren't real. WISE sees in the infrared, well outside the color range our eyes can see. What's displayed as blue and cyan is actually a combination of images taken at the wavelengths of 3.4 and 4.6 microns (about 5 – 7 times the wavelength of the reddest light your eye can detect). Mostly what you see there are stars and some of the warmer dust.

Red in this image (actually light at 22 microns) is from dust (tiny rocky grains smaller than a human hair in size) laced with heavier elements that astronomers call metals. That's the coolest material in the image, and isn't too much warmer than absolute zero.

Most of what you see is green, though, 12 micron light. That's primarily emitted by slightly warmer dust, especially stuff called PAHs: polycyclic aromatic compounds. These are long-chain carbon molecules, and are really, just, well… soot.

Soot? On Rudolph? Did Santa let him take some gifts down the chimney himself?

The left 'ear' is actually another bubble surrounding a cluster of young stars called IC 348. This sort of thing is common for stars being born inside dense gas clouds; their winds and bright ultraviolet light eat away at the inside, expanding that cavity. If they're near the edge of the bigger cloud the bubble can pop, creating a huge blister in the side of the cloud. The famous Orion Nebula is the best example of one of those.

I love pareidolia, seeing recognizable patterns like faces and shapes in otherwise unrelated objects. It happens with astronomical objects a lot; there can be all kinds of interesting shapes that remind us of other things. We name astronomical objects due to this a lot; heck, the constellations are all named this way (some more dubiously than others). In this case, this cloud is named after astronomer Edward Emerson Barnard, who found and mapped quite a few clouds like this one (they appear dark in visible light) so we may be too late to rename it for anything it may look like.

So Barnard 3 it remains… but in my heart of hearts, it will always be the Rudolph Nebula.