Category Archives: Infrared astronomy

astronomy, astronomy news, Infrared astronomy

Stellar News Briefs

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Astronomy Marches On

I’ve been offline the past few days due to a nasty cold (that turned into bronchitis) that I caught while in Florida to catch what turned out to be the “scrub” of the April 29th launch of space shuttle Endeavour. The trip wasn’t a total loss: we got some great images of Endeavour on the pad (see my previous entry about that), and we did our once-every-ten-years-or-so visit to Disney World so we could act like kids again and put on our Mouseketeer hats.

I’m finally up and able to write coherently again, and boy has the news piled on!  So, here’s a look at three of the latest stories with some commentary.

It’s Official: Io is Really, Really Volcanic!

This graphic shows the internal structure of Jupiter's moon Io as revealed by data from NASA's Galileo spacecraft. The low-density crust about 30 to 50 kilometers (20 to 30 miles) thick is shown in gray in the cross-section. Image credit: NASA/JPL/University of Michigan/UCLA

Of course, we’ve all known for years that the little moon Io, which orbits Jupiter, is a volcanic world. But, just HOW volcanic has been confirmed by further analysis of Galileo data. The spacecraft-made measurements show that Io has a subsurface ocean of molten (or partly molten) lava called magma just beneath the surface.  Galileo’s data is the first direct proof that this kind of magma layer exists under the sulfurous rocky crust of this tiny moon.

That subsurface magma sends out about a hundred times MORE lava than all of Earth’s volcanoes combined. Io’s volcanic calderas and vents are scattered across its surface, and their action is enough to completely re-pave this world with lava layers.

The Crab in Motion

The Crab Nebula as seen by Chandra X-ray Observatory. Courtesy NASA/Chandra X-ray Observatory.

One of my favorite supernova remnants is also one of the Chandra X-ray Observatory’s more frequent observing targets.  The folks at Chandra are tracking emissions from the central region of this object, which contains an active pulsar. This week they’ve released a cool little movie that shows changes in the Crab from September 2010 to April 2011.  As you watch the video, you can see some pretty impressive variations in emissions in the structure around the jet at the bottom. You should be able to make out the expansion of a ring of x-ray emission around the pulsar (white dot near center) and changes in the knots within this ring.

However, as the Chandra folks point out on in their release, the arguably the most striking result of these observations is the variations that were not observed, or in analogy with a famous Sherlock Holmes story1, this could be a case where the fact that the dog that did not bark helps to solve a mystery.

The pulsar at the center of the Crab Nebula is a neutron star that spins around about 30 times a second. It was created from a supernova explosion in our galaxy that was observed by astronomers in China and other countries in the year 1054.

As the young pulsar slows down, large amounts of energy are injected into its surroundings. In particular, a high-speed wind of matter and anti-matter particles plows into the surrounding nebula, creating a shock wave that forms the expanding ring seen in the movie. Jets from the poles of the pulsar spew x-ray emitting matter and antimatter particles in a direction perpendicular to the ring. The goal for Chandra’s observations is to pinpoint the location of gamma-ray flares observed by the Fermi spacecraft and Italy’s AGILE satellite. For more information, surf over here.

Star Formation Writ Large in Dwarf Galaxy

Hubble’s newest camera has taken an image of galaxy NGC 4214. This galaxy glows brightly with young stars and gas clouds, and is an ideal laboratory to research star formation and evolution. Courtesy NASA/ESA/STScI.

I’ll close with a gorgeous Hubble Space Telescope look at a star-birth nursery in the dwarf galaxy NGC 4214.  Check this out in “large” mode — it’s beautiful!

This stunner of an image was released earlier today, and is a good look at a starbirth region in a tiny galaxy that, nonetheless, is  packed with everything an astronomer could ask for, from hot, young star-forming regions to old clusters with red supergiants.

What you’re seeing in this image taken in both optical and infrared light by HST’s Wide Field Camera 3, are clouds of glowing ionized hydrogen gas, and in their central regions are cavities blown clear of gas by stellar wind. Nearby are bright star clusters

The huge heart-shaped cavity — possibly the galaxy’s most eye-catching feature — is not just a hole in the clouds. It also contains a large cluster of massive, young stars. They’re hot, too — ranging in temperature from 10,000 to 50 000 degrees Celsius. They blowing out extremely strong stellar winds that are blowing the “bubble” of the cavern free of material. In the process, they’re also closing off any chance for more stars to develop — there’s no more starbirth material left.

Want to know more about this region of space? Check out the full press release and more imagery at www.spacetelescope.org.

astronomy, astronomy news, astronomy research, Infrared astronomy, spitzer space telescope

Come With Me to the Starry City

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And View it in Waves of Infrared Light

Astronomy takes you out there, thataway — and takes your breath away with cosmic visions of loveliness.  If it weren’t for the tools of astronomy that populate our spaceship of exploration, we’d still be seeing the universe in the equivalent of “black and white” TV of mid-last-century.  Those tools, like the Spitzer Space Telescope, with its infrared-sensitive detectors, open up the multi-wavelength universe and let us see things we weren’t able to see before.  Like the North American Nebula, in the constellation Cygnus, the Swan. Spitzer has just released some gorgeous imagery of this formerly mysterious region of space.

The first human to see the North American Nebula was William Herschel, back in 1786. It was merely a smudge to him, as it would be to anyone with a similar type of small telescope like he used.  I once tried to look at this nebula through a pair of fairly strong binoculars and through an 8-inch telescope, and it was faint, indeed. But, the shape of the nebula could be made out — it really does look like the outline of the North American continent.  However, this have changed since Herschel’s day. Today, we have telescopes and spacecraft that can look at wavelengths of light beyond the visible. Those have changed our perceptions of the cosmos.

Actually, what’s really changing is what we’re now able to see.  We’re detecting MORE of what’s in the nebula.  So, for example, we’re seeing infrared radiation given off by hot gas, for one thing. Inky black dust features seen in visible light are also heated, and they start to glow in the infrared view.

Different colors display different parts of the spectrum in each of these images. In the visible-light view (upper right) from the Digitized Sky Survey, colors are shown in their natural blue and red hues. The combined visible/infrared image (upper left) shows visible light as blue, and infrared light as green and red. The infrared array camera (lower left) represents light with a wavelength of 3.6 microns as blue, 4.5 microns as green, 5.8 microns as orange, and 8.0 microns as red. In the final image, incorporating the multi-band imaging photometer data, light with a wavelength of 3.6 microns has been color coded blue; 4.5-micron light is blue-green; 5.8-micron and 8.0-micron light are green; and 24-micron light is red.

This swirling landscape of stars is known as the North America nebula. In visible light, the region resembles North America, but in this new infrared view from NASA's Spitzer Space Telescope, the continent disappears. Where did the continent go? The reason you don't see it in Spitzer's view has to do, in part, with the fact that infrared light can penetrate dust whereas visible light cannot. Dusty, dark clouds in the visible image become transparent in Spitzer's view. In addition, Spitzer's infrared detectors pick up the glow of dusty cocoons enveloping baby stars. Clusters of young stars (about one million years old) can be found throughout the image. Slightly older but still very young stars (about 3 to 5 million years) are also liberally scattered across the complex, with concentrations near the "head" region of the Pelican nebula, which is located to the right of the North America nebula (upper right portion of this picture). Some areas of this nebula are still very thick with dust and appear dark even in Spitzer's view. For example, the dark "river" in the lower left-center of the image -- in the Gulf of Mexico region -- are likely to be the youngest stars in the complex (less than a million years old).

In the bottom two images, only infrared light from Spitzer is shown — data from the infrared array camera is on the left, and data from both the infrared array camera and the multi-band imaging photometer, which sees longer wavelengths, is on the right. These pictures look different in part because infrared light can penetrate dust whereas visible light cannot.

If you look back up at the “visible light” image of the nebula, you’ll see that it’s tough to make out those baby stars and the dusty cocoons where they formed. This is because they’re hidden by dark clouds, which are transparent to infrared light. This lets us peek behind the veil of gas and dust that hides star birth from us.

Baby stars are just part of the scene in the Spitzer image. We can see everything from the stellar cocoons where stars form to newborn stars sporting active jets to so-called “young adult” stars that are becoming more stable, and more capable of sustaining planetary systems.

There’s more to discover in this region of space. Not even Spitzer could reveal all the North American Nebula’s secret, hidden objects. Some of its clouds are just too dense for infrared to penetrate.  And, Spitzer now has no coolant left to chill down its detectors, so some of the longest wavelengths of infrared that it used to be able to detect are no longer available to it. But, that’s not stopping astronomers from studying these images and data. There’s still much to  learn from these observations. Stay tuned!