January 24, 2007, 6:42 PM CT

Corot Sees First Light!

In the night between 17 and 18 January 2007, the protective cover of the COROT telescope has been successfully opened, and COROT has seen for the first time light coming from stars.

Surveying vast stellar fields to learn about star interiors and to search for extra-solar planets is the goal of this unique mission, whose scientific observations will officially start at the beginning of February this year.

The first light detected by COROT comes from the constellation of the Unicorn near Orion, the great 'hunter' whose imposing silhouette stands out in the winter nights. This nice image, taken during the in-orbit calibration exercise, shows that the quality of this preliminary data is basically as good as the computer simulations. "This is an excellent piece of news," commented Malcolm Fridlund, ESA Project Scientist for COROT.

On 18 January, the telescope was carefully aligned with the region to be observed, facing away from the centre of our Galaxy. This setting that will be maintained until April, when the Sun's rays will start to interfere with the observations.

COROT will then rotate by 180 degrees and will start observing the opposite region towards the centre of the Milky Way. In the meantime the COROT researchers are preparing for the science phase to start in February, continuing a thorough examination of the data and the information collected so far.........

Posted by: Sean      Read more         Source

January 24, 2007, 5:53 PM CT

The Sun May Have A Dimmer Switch

THERE'S a dimmer switch inside the sun that causes its brightness to rise and fall on timescales of around 100,000 years - exactly the same period as between ice ages on Earth. So says a physicist who has created a computer model of our star's core.

Robert Ehrlich of George Mason University in Fairfax, Virginia, modelled the effect of temperature fluctuations in the sun's interior. As per the standard view, the temperature of the sun's core is held constant by the opposing pressures of gravity and nuclear fusion. However, Ehrlich believed that slight variations should be possible.

He took as his starting point the work of Attila Grandpierre of the Konkoly Observatory of the Hungarian Academy of Sciences. In 2005, Grandpierre and a collaborator, Gábor Ágoston, calculated that magnetic fields in the sun's core could produce small instabilities in the solar plasma. These instabilities would induce localised oscillations in temperature.

Ehrlich's model shows that whilst most of these oscillations cancel each other out, some reinforce one another and become long-lived temperature variations. The favoured frequencies allow the sun's core temperature to oscillate around its average temperature of 13.6 million kelvin in cycles lasting either 100,000 or 41,000 years. Ehrlich says that random interactions within the sun's magnetic field could flip the fluctuations from one cycle length to the other.........

Posted by: Sean      Read more         Source

January 15, 2007, 7:12 PM CT

NGC 602 and Beyond

Near the outskirts of the Small Magellanic Cloud, a satellite galaxy some 200 thousand light-years distant, lies 5 million year young star cluster NGC 602. Surrounded by natal gas and dust, NGC 602 is featured in this stunning Hubble image of the region. Fantastic ridges and swept back shapes strongly suggest that energetic radiation and shock waves from NGC 602's massive young stars have eroded the dusty material and triggered a progression of star formation moving away from the cluster's center.

At the estimated distance of the Small Magellanic Cloud, the picture spans about 200 light-years, but a tantalizing assortment of background galaxies are also visible in the sharp Hubble view. The background galaxies are hundreds of millions of light-years or more beyond NGC 602.........

Posted by: Sean      Read more

January 11, 2007, 6:43 PM CT

An Astronaut's Endless Endeavor

An astronaut's work, it seems, is never done.

Eileen Collins retired in May, but by October she still hadn't found time to finish cleaning out her office.

"I'm still answering mail from 2005," she said. "I haven't wound down yet. I've been extremely busy."

Of course, that statement could also apply to the past three decades of Collins' life. In 1976, when Collins was a college sophomore, the Air Force announced it would begin training women as pilots. NASA followed suit in 1978 and began accepting women into the shuttle program - just about the time Collins was deciding what to do with her life.

"Those were important years for me," she said. "When the astronaut program opened up to women, that was a huge motivation for me to get my career on the course where I could become a shuttle astronaut someday. And because I was so interested in flying, I wanted to be a shuttle pilot."

Not that it necessarily would have stopped her if the agencies hadn't started accepting women. Collins started planning to become an astronaut long before she would technically have been allowed to. In fourth grade she read a Junior Scholastic Magazine article on the pros and cons of spending money on the space program. Even at the tender age of 8, she couldn't imagine how anyone could think there were cons.........

Posted by: Sean      Read more         Source

January 11, 2007, 4:57 AM CT

Light Echo From The Milky Way's Black Hole

Like cold case investigators, astronomers have used NASA's Chandra X-ray Observatory to uncover evidence of a powerful outburst from the giant black hole at the Milky Way's center.

A light echo was produced when X-ray light generated by gas falling into the Milky Way's supermassive black hole, known as Sagittarius A* (pronounced "A-star"), was reflected off gas clouds near the black hole. While the primary X-rays from the outburst would have reached Earth about 50 years ago, the reflected X-rays took a longer path and arrived in time to be recorded by Chandra.

"This dramatic event happened before we had satellites in space that could detect it," said Michael Muno of the California Institute of Technology in Pasadena. "So, it's remarkable that we can use Chandra to dig into the past and see this monster black hole's capacity for destruction".

Previously, researchers have used Chandra to directly detect smaller and more recent outbursts from the black hole. This latest outburst revealed by the X-ray echo was about 1,000 times brighter and lasted well over 1,000 times longer than any of the recent outbursts observed by Chandra.

Theory predicts that an outburst from Sagittarius A* would cause X-ray emission from the clouds to vary in both intensity and shape. Muno and his team found these changes for the first time, thus ruling out other interpretations. The latest results corroborate other independent, but indirect, evidence for light echoes generated by the black hole in the more distant past.........

Posted by: Sean      Read more         Source

January 9, 2007, 9:53 PM CT

Story Of A Star Death

Using NASA's Chandra X-ray Observatory, researchers have created a stunning new image of one of the youngest supernova remnants in the galaxy. This new view of the debris of an exploded star helps astronomers solve a long-standing mystery, with implications for understanding how a star's life can end catastrophically and for gauging the expansion of the universe.

Over 400 years ago, sky watchers -- including the famous astronomer Johannes Kepler -- noticed a bright new object in the night sky. Since the telescope had still not been invented, only the unaided eye could be used to watch as a new star that was initially brighter than Jupiter dimmed over the following weeks.

Chandra's latest image marks a new phase in understanding the object now known as Kepler's supernova remnant. By combining nearly nine days of Chandra observations, astronomers have generated an X-ray image with unprecedented detail of one of the brightest recorded supernovas in the Milky Way galaxy.

The explosion of the star that created the Kepler remnant blasted the stellar remains into space, heating the gases to millions of degrees and generating highly energized particles. Copious X-ray light, like that shining from a number of supernova remnants, was produced.

Astronomers have studied Kepler intensively over the past three decades with radio, optical and X-ray telescopes, but its origin has remained a puzzle. On the one hand, the presence of large amounts of iron and the absence of a detectable neutron star points toward a so-called Type Ia supernova. These events occur when a white dwarf star pulls material from an orbiting companion until the white dwarf becomes unstable and is destroyed by a thermonuclear explosion.........

Posted by: Sean      Read more         Source

January 9, 2007, 9:21 PM CT

Brightest Supernova

Twenty years ago next month, the closest and brightest supernova in four centuries lit up the southern sky, wowing astronomers and the public alike.

Ongoing observations of the exploded star, called supernova 1987A, provided important tests for theories of how stars die, but it also raised some new questions. Principal among these was how a bizarre, triple-ring nebula surrounding the supernova - ejected by the star a few thousand years before it exploded - originated. Astronomers devised a complicated theory that, within a relatively short period of time, the original star, a red supergiant, merged with a companion and started spinning rapidly, then underwent a transition to a blue supergiant, and finally exploded.

University of California, Berkeley, astronomer Nathan Smith has proposed a different theory for the origin of the nebula, arguing instead that SN1987A's progenitor star may have been in a class of unstable blue supergiant stars, called luminous blue variables, which eject material from their surfaces in recurring, volcano-like eruptions before they finally die in a supernova explosion.

Smith recently discovered two such blue supergiant stars with nebulae closely resembling the peculiarly shaped cloud of dust and gas around SN1987A. A third such nebula was already known.........

Posted by: Sean      Read more         Source

January 8, 2007, 9:32 PM CT

New Stars Shed Light On The Past

new image from the Hubble Space Telescope shows N90, one of the star-forming regions in the Small Magellanic Cloud. The rich populations of infant stars found here enable astronomers to examine star forming processes in an environment that is very different from that in our own Milky Way.

This new image taken with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope depicts bright blue newly formed stars that are blowing a cavity in the centre of a fascinating star-forming region known as N90.

N90 is located in the wing of the Small Magellanic Cloud, in the constellation of Tucana, approximately 200,000 light-years away from the Earth. Its proximity makes it an exceptional laboratory to perform in-depth studies of star formation processes and their evolution in an environment close to that in the early Universe. Dwarf galaxies such as the Small Magellanic Cloud, with small numbers of stars in comparison to our own Milky Way, are considered to be the primitive building blocks of larger galaxies. The study of star formation within this dwarf galaxy is especially interesting to astronomers because its primitive nature means that it lacks a large percentage of the heavier elements that are forged in successive generations of stars through nuclear fusion.........

Posted by: Sean      Read more         Source

January 7, 2007, 8:59 PM CT

Black Hole In Tiny 'Dwarf' Galaxy

Astronomers have found evidence of a supermassive black hole at the heart of a dwarf elliptical galaxy about 54 million light years away from the Milky Way galaxy where Earth resides.

It is only the second time a supermassive black hole has been discerned in a dwarf galaxy, and only the third time that astronomers have observed a double nucleus at the heart of a galaxy, said Victor P. Debattista, a postdoctoral researcher in astronomy at the University of Washington.

The galaxy, called VCC128, lies in the Virgo Cluster and is about 1 percent the size of the Milky Way. All of its stars combined would equal 100 million to 1 billion of our suns, Debattista said.

"It's a very small galaxy, on the outskirts of the cluster," he said. "It is effectively the smallest galaxy in which there is a supermassive black hole".

Black holes lie at the center of a number of galaxies, and have gravitational fields so powerful that nothing - not even light - can escape. A supermassive black hole is so large that its mass equals anywhere between 100,000 and 10 billion of our suns.

Debattista is the lead author of a poster detailing the discovery being presented today at the American Astronomical Society national meeting in Seattle. Co-authors are Ignacio Ferreras of Kings College in London, Anna Pasquali of the Max-Planck-Institut für Astronomie in Gera number of, Anil Seth at the Harvard-Smithsonian Center for Astrophysics in Boston, Sven De Rijcke of the Universiteit Gent in Belgium, and Lorenzo Morelli of Pontificia Universidad Catolica in Chile. The work was funded by a grant from the National Science Foundation, a Brooks Prize Fellowship at the UW and the Fund for Scientific Research in Belgium.........

Posted by: Sean      Read more         Source

January 7, 2007, 7:10 AM CT

A new way to spin up pulsars

A team of researchers using Oak Ridge National Laboratory supercomputers has discovered the first plausible explanation for a pulsar's spin that fits the observations made by astronomers. Anthony Mezzacappa of the Department of Energy lab's Physics Division and John Blondin of North Carolina State University explain their results in the Jan. 4 issue of the journal Nature. As per three-dimensional simulations they performed at the Leadership Computing Facility, located at ORNL, the spin of a pulsar is determined not by the spin of the original star, but by the shock wave created when the star's massive iron core collapses.

That shock wave is inherently unstable, a discovery the team made in 2002, and eventually becomes cigar-shaped instead of spherical. The instability creates two rotating flows-one in one direction directly below the shock wave and another, inner flow, that travels in the opposite direction and spins up the core.

"The stuff that's falling in toward the center, if it hits this shock wave that is not a sphere any more but a cigar-shaped surface, will be deflected," Mezzacappa said. "When you do this in 3-D, you find that you wind up with not only one flow, but two counterrotating flows."

The asymmetrical flows establish a "sloshing" motion that, in the complex 3-D models, accounts for the pulsars observed spin velocities from once every 15 to 300 milliseconds, which is much slower than prior models predicted.........

Posted by: Sean      Read more         Source