Category Archives: astronomy

astronomy, astronomy news, Infrared astronomy

Stellar News Briefs

Leave a comment

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

Looking for Matter

Leave a comment

The Answer to the Question…

How do you search out unusual types of “cosmic stuff” such as dark matter and antimatter?  The response:  you do particle physics.  Now, what’s particle physics?  It’s the science of understanding the makeup and actions and effects of particles (atoms and their constituent components the electrons, quarks, etc.) that make up matter in the universe.

Cosmic rays are a big part of particle physics. They are pieces of atoms called “subatomic particles” that are very energetic.  They zip around the universe at high speeds, they can penetrate our planet’s atmosphere and the surface,  and even your body.

The Alpha Magnetic Spectrometer at KSC before launch. Courtesy NASA.

The next shuttle launch (the last one for Endeavour) will take a unique experiment into space called the Alpha Magnetic Spectrometer (AMS for short).  It will be left on the International Space Station and spend some time doing particle physics.  In its search for antimatter (which is the “anti” version of regular matter), the AMS will look for what’s called an “antihelium” nucleus occurring naturally in the universe. This “stuff” has been observed before in collider experiments where they have been created briefly during high-speed particle collisions.  The instrument is sensitive enough to detect such antimatter at tremendous distances — out to the limits of the expanding universe (where, in its early  moments, there may have been antimatter created as a part of the birth of the cosmos).

The AMS also sets its sensitive sights on the detection of dark matter, that stuff that appears to make up some 95 percent of the mass of the entire universe.  There’s a LOT of it out there, and eventually we’re going to find out what it is.  The AMS will look at the background amounts of positron, anti-proton, or gamma-ray flux (or type of flow). If there are peaks (or jumps) in the flux, then this may tell us about the presence of dark matter (and what it is).

Of course, since the AMS will be in space, studying space, it will give us a lot of information on the cosmic ray counts we encounter in near-Earth space. Cosmic rays come from a variety of sources (including supernova explosions, the Sun, and so on), and knowing the cosmic ray environment at both normal and peak levels helps us understand their role and existence.  In addition, anybody venturing off Earth — whether to the Moon, the ISS, Mars or wherever — has to be continually aware of the cosmic ray levels. These babies are lethal in high doses!

So, how does this weird-looking instrument do its work? It has a set of detectors that are “interested” in various particles.  For example, the transition radiation detector clocks the speeds of very high-energy particles, as does the ring-imaging Cherenkov detector. The AMS also has a superconducting magnet that is strong enough to bend the path of a charged particle and allows it to be identified. Other instruments measure the energy of the particles as they pass through, and give some indication of their coordinates in the magnetic field of the superconducting magnet.  This all makes sense once you understand that these particles are creatures of their magnetic environments and so using speed detectors and magnets to measure their characteristics is the way to go.

While much subatomic physics can be done on the ground at places like CERN and Fermilab and Brookfield National Laboratory (among others), such experiments are usually better conducted in space, away from the Earth’s environment and where the conditions can be more easily understood.  This flight of the AMS module (officially called AMS-02) is another step in stretching our understanding of the smallest particles (and their actions).  For more information about AMS-02, visit the instrument Web page, where you’ll find introductory material, images, and videos.