For some reason, a lot of gorgeous pictures are being released after I post my Top 24 Deep Space Pictures of 2011 gallery. Figures. Since I already had a few images from NASA’s WISE observatory in the gallery anyway I guess can’t complain too much, especially when they release one as pretty as this!

[Click to infraredenate.]

This is Barnard 3, a dusty, gassy region of the galaxy about a thousand light years away where young stars are lighting up their neighborhood. WISE observes the skies in the far infrared, well past what our eye can detect, so this false-color picture mostly picks out the dust warmed by nearby stars. What you see as green and yellow-green is actually from long, complex molecules similar to soot, called polycyclic aromatic hydrocarbons or PAHs. Red shows cooler material.

So what’s going on here? Right in the center of the red splotch is a star which is brighter and hotter than our Sun, and is flooding the surrounding material with ultraviolet light and a fast wind of subatomic particles (like the Sun’s solar wind, but a whole lot stronger and with a much, much farther reach). This has carved out a gigantic cavity in that stuff, creating a bubble about 25 light years in diameter — that’s huge: 250,000,000,000,000 kilometers across, more than 10,000 times the size of our solar system!

(more…)

How cool is this? Literally, the coolest: NASA’s Wide-field Infrared Survey Explorer has found the lowest-temperature brown dwarfs ever seen, the tail end of the stellar class of brown dwarfs called Y dwarfs. How not hot are they? This one (called WISE 1828+2650 if you’re playing brown dwarf bingo), spotted by WISE, has a surface temperature of 25° Celsius — that’s 80° Fahrenheit!

As I sit here and write this, it’s warmer outside my window than it is on the surface of that object!

Not only that, another Y dwarf they found, called WISE 1541-2250, may be the seventh-closest object in the sky outside our solar system. The distance found is not directly measured; it was calculated using the brightness of the brown dwarf. The distance was found using parallax. Even though it’s only about nine light years away, it’s incredibly faint. The only reason it was seen at all is that WISE is tuned to see in the far-infrared, where these things are far brighter than in visible light.

The most exciting part about this is it supports an idea I’ve had (and lots of others have had too) for a long time: Proxima Centauri may not be the closest object to the Sun. A Y-class brown dwarf could be even closer and still have evaded our detection. Even at four light years away — roughly how far Proxima Cen is — a Y star would be pretty hard to see. We may not know for a while yet, but it’s possible.

So what’s the deal with brown dwarfs? (more…)

Astronomers recently discovered two brown dwarfs in our solar neighborhood, and they’re actually pretty close by: 15 and 18 light years away!

[Click to hugely unendwarfenate.]

The two objects were spotted in observations made by WISE, the Wide-field Infrared Survey Explorer, which recently finished its mission to observe the entire sky in infrared light. In the false color images from WISE, brown dwarfs tend to appear very green (fun details are in that link), making them somewhat easy to spot against full-blown stars which tend to appear blue — remember, this is false color!

Anyway, the astronomers were looking for nearby brown dwarfs (PDF), so they searched for green objects that had no obvious counterparts in older infrared surveys. All stars orbit the center of the Milky Way galaxy at different velocities, and over time that means they move across the sky. Nearby stars appear to move fastest (just like the nearby trees fly past you while driving, but distant mountains appear to move more slowly), so nearby brown dwarfs would have moved in the time separating the older surveys from that of WISE.

The astronomers actually found quite a few objects, most of which were known. But these two, called WISE J0254+0223 and WISE J1741+2553, were not previously known — in the picture above, their positions in the older survey from 2000 are labeled compared to their positions in the 2010 WISE images. Remarkably, only 39 star systems (I include multiple stars as one system here) are known to be closer to us than J1741 (which is 15 light years away), and only a handful of them are brown dwarfs (what are called T class objects).

Which, as always when we find new nearby stars, make me wonder: are there faint, cool brown dwarfs even closer to us? Is it possible that Proxima Centauri, a red dwarf 4.2 light years away, is not the closest star to the Sun?

Maybe. The WISE data used to find these two neighbors is not the full set taken by the spacecraft. There’s still quite a bit of data to sift through. Who knows, we may yet find out there’s a star or stars passing by still waiting to make our acquaintance.

NASA’s Wide-field Infrared Survey Explorer (WISE) has found the very first asteroid that (more or less) shares an orbit with Earth! Called 2010 TK₇, this asteroid is about 300 meters (roughly 1000 feet) across, and is the first in an up-to-now theoretical class of objects called Earth Trojans.

Here’s a WISE image of the little bugger:

Doesn’t look like much, does it? Of course, from 80 million km (50 million miles) from Earth it’s amazing we can see it at all. Moreover, given its position in the sky, it’s only up during the day as seen from Earth; it was only discovered because WISE orbits the Earth, so the sky is always dark. Also, WISE sees in the infrared, so warmer objects are easier to spot. This rock is probably around the freezing point of water or so, which, to an astronomer, is pretty warm.

So what makes this asteroid special?

(more…)

Spiral galaxies are among the most beautiful objects in the sky, and one of the most beautiful of them is M101, also known as the Pinwheel Galaxy. It’s a reliable favorite among amateur astronomers because it’s big, bright, and located near the north pole of the sky, so it’s easy to find for a big part of the year.

I’ve seen it many times through a telescope, but not quite like the way NASA’s Wide-field Infrared Survey Explorer (WISE) saw it: glowing fiercely in colors our eyes cannot detect:

[Click to galactinate.]

This image shows the galaxy in the far-infrared. What you see here as blue is actually starlight; green is from long organic compounds called PAHs, and red is from glowing dust, warmed by nearby star formation. Look at the gigantic red clouds where stars are being born! Thousands of these have been catalogued in the Pinwheel.

It’s actually an immense galaxy, twice the diameter of the Milky Way and possessing as many as ten times the number of stars. Our galaxy is no lightweight, but the Pinwheel is a monster. I wrote about it when Hubble released a gorgeous and incredibly detailed image of it back in 2006. There’s also a spectacular Spitzer image of it as well, which is also in the infrared, though in a different part of the IR spectrum.

The WISE mission shut its eye earlier this year when it ran out of coolant to keep its detectors cold (warm objects emit lots of IR, so keeping things cold prevents the detectors themselves from glowing in the very light they’re designed to see), but it surveyed the entire sky, returning a whole lot of data. I imagine we’ll be seeing more pictures like this coming from the database, as well as lots of amazing discoveries as scientists pore over it. The mission itself may be done, but the information it gave us goes on.

Image credit: NASA/JPL-Caltech/UCLA