Category Archives: planetary science

astronomy, astronomy media, astronomy news, astrophysics, galaxies, planetary science, starbirth

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!

planetary science

Geophysical and Planetary Delights

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Scientists Exploring Planets

The American Geophysical Union began its fall meeting today in San Francisco and already there is some fascinating news coming out from the planetary science hive mind attendees. Of course I find it all interesting, but of particular interest today was a press conference (that I watched via the AGU press website) about a connection between solar wind disturbances and a “breathing” action — an expansion and contraction —  of Earth’s upper atmosphere. One of the projects I’m working on right now is a series of video podcasts explaining how solar activity affects our atmosphere and magnetosphere, so this kind of information was right up our team’s alley!

There was also a rather startling result released by a group of scientists who maintain that a series of volcanic eruptions some 65 million years ago is what REALLY caused the death of the dinosaurs and not the impactor that carved out the Chicxulub meteor crater in Yucatan, Mexico. The team’s data show that the K-T extinction that we normally associate with the impact event actually coincided with the end of a major volcanism event in India. The volcanic outpouring spewed at least 30 times more sulfur dioxide, the suspected killing agent, than did the Chicxulub impact. In Mexico and Texas, melt rock spherules discovered in sediments well below the K-T boundary indicate that the Chicxulub impact predates the mass extinction by about 300,000 years, leaving no significant biotic effects.

This is all very fascinating, and I imagine that this result will spur some vehement discussions among the various proponents of different theories about the mass extinction of 65 MYA.  However, I am a bit skeptical of the claim that an event that carved out a crater the size of the Chicxulub crater really didn’t have much effect on life.  I think there’s still more work to be done to understand the entire sequence of events that led up to the ultimate demise of so many species around the time of the dinosaur die-off, and it will be interesting to see how it all works out.

Enceladus provides a tectonic feast for the eyes! Courtesy NASA and the Cassini Mission team.
Enceladus provides a tectonic feast for the eyes! Courtesy NASA and the Cassini Mission team.

Then there’s the ongoing excitement of Saturn exploration, in particular the Enceladus connection through Cassini. The closer the Cassini scientists look at Enceladus, the more they are convinced that this world is dynamic and active! In particular, the south pole surface changes over time scales that they can study with the spacecraft. That means it changes on the order of days or weeks!

Close-up observations show jets that spew water vapor and ice particles from beneath the surface — that’s what gives those “tiger stripes” that we see. The surface responds to pressure from below and you see giant cracks that have formed as the surface units shift.

What’s even more exciting is that along with the water vapor, scientists are seeing organic compounds and telltale signs of excess heat emerging from beneath the icy surface.  There could be a liquid-water-rich zone beneath the ice where life could fluorish (if it exists).

Finally, among all the other press conferences was one given by the folks involved with the Mars Phoenix Lander that just went to sleep for good a few weeks ago. The data from this mission is far from being completely analyzed, but the team did point out that the arctic soil it studied is very cold and dry right now. However, long-term climate cycles could well make the planet moist enough to modify the soil’s chemistry.  All this information is being folded into their models of the Mars long-term climatology and the action of water vapor as it moves from the atmosphere to the soil and back again.

The soil trench scooped up by the Mars Phoenix Lander.
The soil trench scooped up by the Mars Phoenix Lander. Courtesy NASA and the Mars Phoenix Lander team.

Peter Smith, the principal investigator for the Phoenix mission described what they found. “We have snowfall from the clouds and frost at the surface, with ice just a few inches below, and dry soil in between,” he said. “During a warmer climate several million years ago, the ice would have been deeper, but frost on the surface could have melted and wet the soil.”

Another one of the mission scientists, Ray Arvidson, commented further on the action of water on Martian soil. “The ice under the soil around Phoenix is not a sealed-off deposit left from some ancient ocean,” he said. “It is in equilibrium with the environment, and the environment changes with the obliquity cycles on scales from hundreds of thousands of years to a few million years. There have probably been dozens of times in the past 10 million years when thin films of water were active in the soil, and probably there will be dozens more times in the next 10 million years.”

The soil that Phoenix scooped up was cloddy (meaning that it clumped together).  That clumpiness is one clue to the effects that water has on soil. The spacecraft did a microscopic study of the soil and found that it was made up of individual particles that are very likely windblown dust and sand. However, the clods of the soil hold together more cohesively than expected for unaltered dust and sand. Arvidson said, “It’s not strongly cemented. It would break up in your hand, but the cloddiness tells us that something is taking the windblown material and mildly cementing it.”

That cementing effect could result from water molecules adhering to the surfaces of soil particles. Or it could be from water mobilizing and redepositing salts that Phoenix identified in the soil, such as magnesium perchlorate and calcium carbonate. If you want to read more about this finding, zip on over to the Mars Phoenix mission site, where they have more details on the action of water and ice in the Martian soil.

I’ll be tuning in to AGU again tomorrow to hear the latest in geophysical and planetary science findings.  You stay tuned, too!

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Thanks to Daniel Fischer, who writes the Cosmic Mirror pages, for alerting me to the online live press conferences. I’d gotten the notification about them, but in the excitement surrounding our recent power outages due to that nasty ice storm, I’d forgotten until he mentioned the conference to me in Twitter.