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Dispatches from the Cosmos

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Monday, January 5, 2009

Astronomy is truly a science that takes you places.  At one level, it has brought ME to Long Beach, CA to hear about the latest and greatest astronomy discoveries. At another level, it is bringing us (scientists, writers — and  ultimately our audiences) out to the most fascinating places in the cosmos.

“Where?” you ask.  How about the core of the Milky Way Galaxy? Q.D. Wang of the University of Massachusetts at Amherst used the Hubble Space Telescope to make an infrared mosaic of the center of our galaxy.  It’s a beautiful panoramic view that takes in an area of space measuring 300 x 150 light-years.

The core of the Milky Way in an infrared mosaic from Hubble Space Telescope.
The core of the Milky Way in an infrared mosaic from Hubble Space Telescope. (click to embiggen)

This is a “false-color” image taken through a filter that reveals the glow of hydrogen gas heated by winds from new stars revealed as a new population of massive stars at the core. And the cool thing is that this is the sharpest infrared picture ever made of the galactic core.

Astronomers are looking at this region to understand how massive stars form and what they do to their local enviroment during their tempestuous birth process. If we can understand how it works in OUR galaxy then we have insight into how it works in the cores of other galaxies, particularly the active ones.  Read more about this fascinating image at at the Space Telescope web site.

This 0.6 by 0.7-degree infrared photograph of the galactic center shows a large population of old, red stars. However, the discovery of two young protostars within a few light-years of the center of the Milky Way shows that stars can form there despite powerful gravitational tides due to the supermassive black hole. Credit: 2MASS/E. Kopan (IPAC/Caltech)
This 0.6 by 0.7-degree infrared photograph of the galactic center shows a large population of old, red stars. However, the discovery of two young protostars within a few light-years of the center of the Milky Way shows that stars can form there despite powerful gravitational tides due to the supermassive black hole. Credit: 2MASS/E. Kopan (IPAC/Caltech)

Now, looking at the center of the galaxy is difficult, since it’s shrouded in dust clouds. The good news is that we can plumb those depths using infrared and radio telescopes. Astronomers at Harvard-Smithsonian Center for Astrophysics and the Max Planck Institute for Radio Astronomy have used the Very Large Array in New Mexico to study young stars that really shouldn’t be there.

This is because the core of the galaxy is not a gentle creche where young stars should be able to form. It’s wracked with powerful radiation and gravitational tides stirred up by the four-million-solar-mass black hole that’s hidden at the core. It’s a place where stars go to get gobbled up, not get born.

So, nobody’s sure how a pair of protostars started to form at a spot only a few light-years from the galactic center. What this tells us is that this place, as wild as it might be, can still nurture star formation. Now astronomers will spend time figuring out how and why this is happening.

Artist's Conception of our Milky Way Galaxy: Blue, green dots indicate distance measurements. CREDIT: Robert Hurt, IPAC; Mark Reid, CfA, NRAO/AUI/NSF

This scenario may suggest that star-forming clouds may be much denser than we thought.  For more information, check out the story here.

Continuing our look at the Milky Way, the folks at the National Radio Astronomy Observatory are looking at our galaxy using the Very Long Baseline Array radio telescope and what they’re finding is redefining what we know about our galactic home. Essentially, the Milky Way is rotating faster, is heavier, and is more likely to collide with other galaxies than we used to think.

You can read more about their findings at the link above, but just to give you an example of what they’ve found: at our location in the galaxy — some 28,000 light-years away from the core of the galaxy — we’re speeding along at 960,000 kilometers per hour (600,000 miles an hour).

An asteroid bites the dust around white dwarf star.
An asteroid bites the dust around white dwarf star.

A little closer to home, astronomers continue to focus attention (and detectors) on exoplanets — worlds circling other stars.

The white dwarf GD40 and five other similar type stars came in for some attention by Mike Jura of the University of California, who used the Spitzer Space Telescope to study the remains of asteroids chewed up as the stars went through their red giant phase and then shrank down to  become a white dwarf. That chewing action generated dust, which can be spotted with infrared-sensitive detectors. A star with MORE dust around it is “brighter” in infrared than a star with NO dust.

Ultimately, what their research suggests is that the same materials that made up our planet and other rocky worlds may be pretty common in the galaxy and the universe. You can read more about their work here.

NGC 2362 This photograph from NASAs Spitzer Space Telescope shows the young star cluster NGC 2362. By studying it, astronomers found that gas giant planet formation happens very rapidly and efficiently, within less than 5 million years, meaning that Jupiter-like worlds experience a growth spurt in their infancy. Credit: NASA/JPL-Caltech/T. Currie (CfA)
NGC 2362 This photograph from NASA's Spitzer Space Telescope shows the young star cluster NGC 2362. By studying it, astronomers found that gas giant planet formation happens very rapidly and efficiently, within less than 5 million years, meaning that Jupiter-like worlds experience a growth spurt in their infancy. Credit: NASA/JPL-Caltech/T. Currie (CfA)

One of the more intriguing stories is about how baby Jupiters form around other stars.

It turns out that, according to scientists at the Harvard-Smithsonian Center for Astrophysics (who used the Spitzer Space Telescope to look at stars in the cluster NGC 2362 to detect infrared signatures of active planetary formation) a Jupiter-type planet has a pretty short time frame to form before the dynamics of the system shut off the process.

For our solar system, that means that Jupiter took only 2 to 3 million years to spring into being, whereas Earth took 20 to 30 million years to aggregate and solidify. Read more here.

Finally (for now, anyway), I got a press release detailing the upcoming WISE mission, which will provide a highly detailed all-sky survey in the infrared, from 3 to 25 microns. It’s supposed to launch in 2009 and will map the sky for at least seven months.  The scientists who use this instrument hope to find the most luminous galaxies in the universe, find the closest stars to the Sun, detect most of the asteroids in the Main Belt, and do a number of different studies of planetary discs around other stars.

Check out the WISE web site for more details.

Okay, there’s more to come, so stay tuned!

astronomy news, astrovisualization, hubble space telescope, starbirth, stars

Hey, You! Yeah, Look at THOSE Bright Stars!

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Follow the Pointer

A wide-field image of WR-25 and Tr16-244 in the Carina Nebula. Courtesy NASA/ESA Hubble Space Telescope.
A wide-field image of WR-25 and Tr16-244 in the Carina Nebula. Courtesy NASA/ESA Hubble Space Telescope.

My friend Phil Plait has a thing about instances of pareidolia — the tendency of humans to see interesting patterns in things.  It’s a peculiar psychological thing that our primate brains do to us when we see things we don’t immediately understand or can’t place in context. So, for example, you look up at clouds in the sky and see spaceships or dogs playing or sheep sleeping or whatever it is that the cloud seems to resemble. And, of course, there are tendencies among some folks to see things like faces of deities in toast and tortillas, or peeling paint, or the bark on trees. It’s all very amusing and shows you how complex our brains are.

Astronomy images provide hours of merriment for pareidoliacs.  Take this picture, for example.  It’s a Hubble Space Telescope view of a gas and dust cloud where star formation is taking place. Notice in the very top of the picture that there’s a thick cloud of dust in the shape of a pointing finger. At least, that’s what it looks like to me.  And, it  might appear that way to you, too.

Well, you might ask — what’s it pointing to?  Good question, and the answer is what the subject of the image really is:  a pair of massive bright stars down in the lower third of the image that are shining out like a pair of headlights. (Or, if you’re a fan of LOLcats, they look like “cat lazors” charging up.)

This scene is smack in the middle of the Carina Nebula, a huge region where clouds of gas and dust are combining to form new stars. It is about 7,500 light-years away from us, and also contains the luminous blue variable Eta Carinae, which is expected to pop off as a supernova pretty much any time now (in cosmic terms).

It turns out those two bright stars have an interesting connection to the pointy-finger cloud. The bright star in the lower center is called WR-25, and its quite massive — more than 50 times the mass of our Sun.  In fact, it’s really two stars orbiting a common center of mass. They hot, bright, and interacting with each other.

The star to the left of WR-25 is called Tr16-244, and it’s actually three stars orbiting a common center of gravity — a triple-star system. Together, these two star systems are eating away at the clouds of gas and dust. That “cannibalization by radiation” is actually what sculpted the finger-shaped cloud. It’s amost as if the cloud is pointing the finger of blame back to the stars that shaped it — a nice case of cosmic pareidolia.