Desktop Project Part 9: Again I see IC 342

By Phil Plait | April 3, 2012 9:25 am

[Over the past few weeks, I’ve collected a metric ton of cool pictures to post, but somehow have never gotten around to actually posting them. Sometimes I was too busy, sometimes too lazy, sometimes they just fell by the wayside… but I decided my computer’s desktop was getting cluttered, and I’ll never clean it up without some sort of incentive. I’ve therefore made a pact with myself to post one of the pictures with an abbreviated description every day until they’re gone, thus cleaning up my desktop, showing you neat and/or beautiful pictures, and making me feel better about my work habits. Enjoy.]

IC 342 is a relatively close by face-on spiral galaxy. At 10 million light years distant, it should actually be easily visible in binoculars and would be renowned for its incredible beauty except for one small problem: we have to peer through the thick dust choking our own galaxy to see it. It’s like sitting in a smoky room and trying to see something out the window on the far side of it. Your view is obscured.

But infrared light passes through dust quite easily, so when you turn an IR telescope — like NASA’s Spitzer Space Telescope — toward IC 342, what you get is spidery magic!

[Click to embiggen.]

Holy wow! What you’re seeing is the dust in IC 342 glowing where stars are being born; giant gas clouds are star birth factories, and are shrouded in dust. The stars’ light warms the dust up and it glows. The vast complex of nebulae trace out the spiral arms, looking like a web knit by an astronomically-minded spider.

I’ve written about IC 342 twice before. Once was when the NOAO released a gorgeous image of it taken by my friend Travis Rector. Seriously, click that link. The image is spectacular.

The other time was last year when WISE, another infrared observatory, took a look at IC 342. The view is pretty similar, as you might expect — the parts of the infrared spectrum making up both images are nearly the same — but Spitzer’s mirror is twice the size of the one in WISE, so the resolution is somewhat better.

Still, the more the merrier! IC 342 is a dramatic example of a nearby face-on spiral, and there aren’t too many of those around. Even though our own Milky Way galaxy has photobombed it into relative obscurity, the prying eyes of science are pretty good at seeing through all that.

Related Posts:

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S marks the spot
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CATEGORIZED UNDER: Astronomy, Pretty pictures

Desktop Project Part 2: Unicorn, rainbow… soot?

By Phil Plait | March 27, 2012 7:00 am

[Over the past few weeks, I’ve collected a metric ton of cool pictures to post, but somehow have never gotten around to actually posting them. Sometimes I was too busy, sometimes too lazy, sometimes they just fell by the wayside… but I decided my computer’s desktop was getting cluttered, and I’ll never clean it up without some sort of incentive. I’ve therefore made a pact with myself to post one of the pictures with an abbreviated description every day until they’re gone, thus cleaning up my desktop, showing you neat and/or beautiful pictures, and making me feel better about my work habits. Enjoy.]

Did you know there’s a unicorn in the sky? There is: the constellation Monoceros (literally, one-horn). Located near Orion, when we look in that direction we’re peering into the disk of our Milky Way galaxy, and that means seeing lots of gas and dust. And when you do that with a telescope like WISE that sees into the far-infared, what you get is, well, magic:

This is SH2-284, a star forming nebula. The image is false color, but each hue represents a different part of the infrared spectrum. Blue and teal is mostly coming from stars, while red and yellow is dust. Green comes from a very specific kind of material called a polycyclic aromatic hydrocarbons — long-chain carbon molecules which are essentially soot. PAHs are made in various ways, but are abundant where stars are being born, and that’s what we’re seeing here.

There’s a cluster of young stars in the center of this cloud, and they’re so hot they’re eating out the inside of the cloud, creating that cavity you can see. Like so many of these structures, the clock is ticking: many of those stars will explode, and when they do they’ll tear the cloud apart. So take a look while you can… this unicorn rainbow cloud only has a few million years left before it’s extinct.

Image Credit: NASA/JPL-Caltech/WISE Team

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CATEGORIZED UNDER: Astronomy, Pretty pictures

Gallery: Cosmic pictures from the AAS

By Phil Plait | January 17, 2012 7:00 am

[zenphotopress album=328 sort=sort_order number=13]

Rudolph the red-dusted Strömgren sphere

By Phil Plait | December 23, 2011 10:48 am

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!

Read More

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures
MORE ABOUT: Barnard 3, dust, infrared, PAHs, WISE

Top 24 Deep Space Pictures of 2011

By Phil Plait | December 14, 2011 5:30 am

[zenphotopress album=323 sort=sort_order number=29]

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

WISE finds coolest brown dwarfs ever seen!

By Phil Plait | August 24, 2011 6:29 am

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? Read More

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures
MORE ABOUT: brown dwarfs, WISE, y dwarfs

Two new nearby brown dwarfs found

By Phil Plait | August 9, 2011 7:00 am

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.

Related posts:

WISE finds the coolest stars. Literally.
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Are we in danger from a rogue planet?
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MORE ABOUT: brown dwarfs, WISE

WISE finds the very first Earth Trojan asteroid

By Phil Plait | July 27, 2011 11:17 am

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?

Read More

CATEGORIZED UNDER: Astronomy, Cool stuff, Top Post

The heat of the Pinwheel

By Phil Plait | July 25, 2011 7:00 am

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

Related posts:

The Triangulum galaxy writ large
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CATEGORIZED UNDER: Astronomy, Pretty pictures

The WISE family comets

By Phil Plait | June 3, 2011 7:00 am

In the little over one year that the Wide-field Infrared Survey Explorer (WISE) spacecraft surveyed the sky, it captured images of hundreds of millions of objects. Many of these were previously known stars, galaxies, and the like, but it also added a few newcomers to our catalogs, including a score of comets:

[Click to encomanate.]

Why did WISE find them, and not ground-based observers? Lots of reasons come to mind. Comets are not really the spectacular and brilliant objects commonly thought; at least, not all of them are. The solid part of a comet is usually a mix of rock and ice, the ice being made of water, ammonia, carbon dioxide, and other materials we tend to think of as gases here on Earth. But in the depths of space, where it’s cold, they can remain frozen solid… until the comet nears the Sun. Then, the materials go from a solid directly to a gas, surround the solid nucleus, and reflect a whole lot more sunlight. The comet gets bright and can be spotted more easily.

Even then, it may not be easy. The comet may be small and faint in optical light. It may be too near the Sun to spot. It may be too far away to be seen easily. Or it may simply not be in a place anyone on Earth is looking.

WISE scanned the entire sky, and was prone to seeing such things. And the lack of optical light isn’t so much an issue if the comet is warm enough to glow in the infrared, and that can be at temperatures a hundred degrees below 0 or more. And even then, WISE only found 20 such comets before anyone here on Earth did. I’ll note it also did see quite a few comets discovered on Earth first, like the comet C/2007 Q3, also known as Siding Spring.

It also racked up a huge number of previously unknown asteroids, some of which are potentially dangerous to the Earth some time in the (far, hopefully) future. The point is — and I’ve said this many times before — the more eyes we have on and in the sky, the better. And by looking at different wavelengths we’ll see even more.

Image Credit: NASA/JPL-Caltech/UCLA

Related posts:

The first spectacular views of the sky from WISE
WISE uncovers its first near-Earth asteroid
A taste of WISE galaxies
Orion’s WISE head

CATEGORIZED UNDER: Astronomy, Pretty pictures
MORE ABOUT: comets, infrared, WISE

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