Back to the main page

Archives Of Astronomy Blog

Subscribe To Astronomy Blog RSS Feed  RSS content feed What is RSS feed?


June 20, 2006, 8:57 PM CT

Cluster Makes An Effervescent Discovery

Cluster Makes An Effervescent Discovery This artist’s impression shows the Earth’s magnetosphere
Space is fizzing. Above our heads, where the Earth's magnetic field meets the constant stream of gas from the Sun, thousands of bubbles of superheated gas are constantly growing and popping.

Their discovery could allow researchers to finally understand the interaction between the solar wind and the Earth's magnetic field.

This exciting new view of near-Earth space has been made possible by ESA's four-spacecraft flotilla, Cluster, and Double Star, ESA's collaborative space mission with China. The spacecraft encounter the bubbles every time they are on the day-lit side of the Earth, at altitudes of between 13 and 19 Earth radii.

The bubbles, known as density holes, are regions of space where the density of gas suddenly falls by ten times but the temperature of the remaining gas leaps from 100 000 ºC to 10 000 000 ºC.

When Cluster first flew through the bubbles, George Parks, University of California, Berkeley, thought that they were just instrumentation glitches. "Then I looked at the data from all four Cluster spacecraft. These anomalies were being observed simultaneously by all the spacecraft. That's when I believed that they were real," says Parks.

Somewhat similar bubbles have occasionally been encountered in the past by other spacecraft. They were called hot flow anomalies but Parks decided the bubbles he saw are significantly different.........

Posted by: Edwin      Permalink         Source


June 18, 2006, 12:01 AM CT

Mini-planet Systems Get Stranger

Mini-planet Systems Get Stranger A brown dwarf companion (bottom left) was also surrounded by a disc
Mini planetary systems may orbit cosmic objects that are 100 times smaller than our Sun, research suggests.

Discs of gas and dust, the ingredients needed to create such systems, have been seen circling these relatively small objects, dubbed "planemos".

If the discs were capable of evolving larger aggregations of material, it would blur the definition of the word "planet", researchers said.

The work was presented at the American Astronomical Society meeting in Canada.

Cosmic newborns

The study is based on observations from European Southern Observatory (ESO) telescopes. It looked at a number of recently identified planemos (an unofficial term sometimes used to describe planetary mass objects).

Located about 450 light-years away in a star-forming region, four of the objects are just a few million years old, making them cosmic "newborns". They have masses between five and 15 times that of Jupiter. ........

Posted by: Edwin      Permalink         Source


June 18, 2006, 11:44 AM CT

NASA Gives Green Light For Discovery Launch

NASA Gives Green Light For  Discovery Launch Image above: Amid the glow of lights from the fixed and rotating service structures, Space Shuttle Discovery rests on the hardstand of Launch Pad 39B at NASA's Kennedy Space Center. Photo credit: NASA/Ken Thornsley
NASA senior managers on Saturday cleared the Space Shuttle Discovery for a July 1 flight to the International Space Station.

The decision was announced after a lengthy Flight Readiness Review, a traditional meeting in which top NASA managers and engineers set launch dates, determine whether the shuttle's complex array of equipment, support systems and procedures are ready for flight and assess any risks associated with the mission.

"We had two full days of an intensive Flight Readiness Review," said Administrator Michael Griffin. "It was spirited and one of the most open, yet non-adversarial meetings I've seen since returning to NASA".

+ Read Press Release.

William Gerstenmaier, Associate Administrator for Space Operations said "It was a tremendously good review. We were really careful in this. We reviewed everything we could and we think we are ready to go and fly".

"The ice frost ramps were one of the most vigorously discussed items. This [foam loss], is what we expect to see in flight. So when we get this data down, you should not be surprised," continued Gerstenmaier.

The ice/frost ramps are structures made of insulation foam that cover 34 brackets on the outside of the shuttle's external fuel tank. The ramps have been cited as a potential source of foam loss, which could cause damage to the shuttle. The Flight Readiness Review board decided the current design does not pose sufficient risk to delay the upcoming mission while design improvements for later flights are under way.........

Posted by: Edwin      Permalink         Source


June 11, 2006, 12:46 AM CT

FUSEing Carbon Planets

FUSEing Carbon Planets
Researchers using NASA's Far Ultraviolet Spectroscopic Explorer, or FUSE, have discovered abundant amounts of carbon gas in a dusty disk surrounding a well-studied young star named Beta Pictoris.

Asteroids and comets orbiting Beta Pictoris might contain large amounts of carbon-rich material, such as graphite and methane. Planets forming from or impacted by such bodies would be very different from those in our solar system and might have methane-rich atmospheres, like Titan, a moon of Saturn.

The star and its emerging solar system are less than 20 million years old, and planets may have already formed. The abundance of carbon gas in the remaining debris disk indicates that the star's planets could be exotic, carbon-rich worlds of graphite and methane. Or conversely, the scientists say, Beta Pictoris and its environs might resemble our own solar system in its early days.

A team led by Dr. Aki Roberge of NASA Goddard Space Flight Center in Greenbelt, Md., presents the FUSE observation in the June 8 issue of Nature. The new measurements make Beta Pictoris the first disk of its kind whose gas has been comprehensively studied. The discovery settles a long-standing scientific mystery about how the gas has lingered in this debris disk yet raises new questions about the development of solar systems.........

Posted by: Edwin      Permalink         Source


June 10, 2006, 6:51 PM CT

Ancient caldera in Apollinaris Patera

Ancient caldera in Apollinaris Patera
Credits: ESA/DLR/FU Berlin (G. Neukum)

See high resolution image

Apollinaris Patera is an ancient shield volcano measuring approximately 180 by 280 kilometres at its base and rising to a maximum of 5 kilometres above the surrounding terrain. Shield volcanos are large volcanic structures with gently sloping flanks. The caldera of Apollinaris Patera takes the form of a large crater approximately 80 kilometres in diameter. In this false-colour image, north is to the right. The image also shows the terrain partly covered by thin, diffuse clouds indicated by bluish-tinted areas.

This false-colour image was captured on 26 October 2004 by the High-Resolution Stereo Camera (HRSC) onboard the ESA spacecraft Mars Express with a ground resolution of approximately 11.1 metres per pixel.........

Posted by: Edwin      Permalink         Source


June 9, 2006, 0:13 AM CT

Why Space Is Dusty

Why Space Is Dusty
Massive star supernovae have been major "dust factories" ever since the first generations of stars formed several hundred million years after the Big Bang, as per an international study published in Science Express today.

The scientific team trained their telescopes on Supernova 2003gd, which exploded in the NGC 628 spiral galaxy 30 million light-years from Earth. The light from the 2003gd first reached Earth on March 17, 2003. At its brightest, it could be seen in an amateur astronomer's telescope. While a number of supernovae are discovered each year, this particular one stood out because it was relatively nearby and could be followed for a longer-than-usual time by the specialized infrared detectors of the Spitzer Space Telescope, and by a spectrograph on the Gemini North telescope. "2003gd is, quite literally, the smoking gun," says Doug Welch, professor, physics & astronomy at McMaster University, and one of 17 astronomers involved in the study. "These carbon and silicon dust particles which form from the supernovae blast make possible the a number of generations of high-mass stars and all the heavy elements they produce. These are elements which make up the bulk of everything around us on Earth, including you and me."

Welch and co-author Geoff Clayton of Louisiana State University, visited the Gemini North telescope in Hawaii to take spectra of ancient massive star supernovae in their hunt for the formation of dust.........

Posted by: Edwin      Permalink         Source


June 7, 2006, 11:51 PM CT

Forming Super-earths By Ultraviolet Stripping

Forming Super-earths By Ultraviolet Stripping Image courtesy of rogers-md.net
A new explanation for forming "super-Earths" suggests that they are more likely to be found orbiting red dwarf stars--the most abundant type of star--than gas giant planets like Jupiter and Saturn. The theory, by Dr. Alan Boss of the Carnegie Institution's Department of Terrestrial Magnetism, describes a mechanism whereby UV radiation from a nearby massive star strips off a planet's gaseous envelope exposing a super-Earth. The work, reported in the June 10, 2006, Astrophysical Journal (Letters), explains recent extrasolar planet discoveries by the microlensing method.

Super-Earths have masses that range between those of Earth and Neptune but have unknown compositions. "Of the 300 stars closest to the Sun, at least 230 are red dwarf stars, with masses less than half that of our Sun," Boss says. "Because nearby stars are the easiest places to look for other Earth-like planets, it is important to try to predict what types of planetary systems they might have, and that means trying to figure out how their planets can form."

Recently, evidence was presented for perhaps the lowest-mass planet found to date in orbit around a main sequence star like the Sun. It was found by an international consortium of astronomers via a microlensing event, where a foreground star amplifies the light from a much more distant star by bending the light of the background star in our direction, an effect predicted by Einstein. In addition, they observed a secondary brightening as well, consistent with the presence of a roughly 5.5-Earth-mass planet orbiting the foreground star at a distance similar to the asteroid belt in our Solar System. While the identity of the foreground star is unknown, it is most likely a red dwarf (M dwarf) star. Evidence for microlensing by a 13-Earth-mass planet around another red dwarf was subsequently presented.........

Posted by: Edwin      Permalink         Source


June 7, 2006, 0:02 AM CT

Young Supernova Remnants Not Dusty Enough

Young Supernova Remnants Not Dusty Enough

One of the youngest supernova remnants known, a glowing red ball of dust created by the explosion 1,000 years ago of a supermassive star in a nearby galaxy, the Small Magellanic Cloud, exhibits the same problem as exploding stars in our own galaxy: too little dust.

Recent measurements by University of California, Berkeley, astronomers using infrared cameras aboard NASA's Spitzer Space Telescope show, at most, one-hundredth the amount of dust predicted by current theories of core-collapse supernovae, barely the mass of the planets in the solar system.

The discrepancy presents a challenge to researchers trying to understand the origins of stars in the early universe, because dust produced primarily from exploding stars is believed to seed the formation of new-generation stars. While remnants of supermassive exploding stars in the Milky Way galaxy also show less dust than predicted, astronomers had hoped that supernovae in the less-evolved Small Magellanic Cloud would accord more with their models.

"Most of the prior work was focused only on our galaxy because we didn't have enough resolution to look further away into other galaxies," said astrophysicist Snezana Stanimirovic, a research associate at UC Berkeley. "But with Spitzer, we can obtain really high resolution observations of the Small Magellanic Cloud, which is 200,000 light years away. Because supernovae in the Small Magellanic Cloud experience conditions similar to those we expect for early galaxies, this is a unique test of dust formation in the early universe".........

Posted by: Edwin      Permalink         Source


June 5, 2006, 9:08 PM CT

Galaxy Evolution In Cyber Universe

Galaxy Evolution In Cyber Universe 13.4 Billion Years After the Big Bang
Researchers at the University of Chicago have bolstered the case for a popular scenario of the big bang theory that neatly explains the arrangement of galaxies throughout the universe. Their supercomputer simulation shows how dark matter, an invisible material of unknown composition, herded luminous matter in the universe from its initial smooth state into the cosmic web of galaxies and galaxy clusters that populate the universe.

Prior studies by other scientists had already verified the main features of this scenario, called the cold dark matter model. The Chicago team further extended this work by comparing the results of their supercomputer simulations to the newest, most detailed astronomical observations available today. They found an excellent fit, and they did so without basing their simulations on a lot of complex assumptions.

"The model we use is really, really simple," said Andrey Kravtsov, Associate Professor in Astronomy & Astrophysics. "We want to see how well this framework can do with a minimum number of assumptions".

A paper co-authored by Kravtsov, Charlie Conroy and Risa Wechsler describing these findings would be reported in the June 20 issue of the Astrophysical Journal. The research was funded by a grant from the National Science Foundation, with additional support from the National Aeronautics and Space Administration.........

Posted by: Edwin      Permalink         Source


June 4, 2006, 1:39 PM CT

Big astronomy project for Chile

Big astronomy project for Chile
With new support for additional federal funding, the largest ground-based astronomy project is unfolding in the high Chilean desert.

The $1 billion Atacama Large Millimeter Array, or ALMA, will look as far back in time as 1 billion years after the Big Bang, producing a kind of astronomical baby book for researchers to peruse.

When completed about 2012, the array will allow astronomers to examine planet and star formation, the formation of early galaxies and galaxy clusters and the detection of organic and other molecules in space.

Formal planning for the project started in the 1990s with the Charlottesville-based National Radio Astronomy Observatory. Since then, it has been beset by a changing global economy and ballooning costs, issues peculiar to the site located 16,500 feet above sea level and international government bureaucracies. New partners have signed on, but the U.S. share is now $566 million.........

Posted by: Edwin      Permalink         Source


Older Blog Entries   1   2   3   4   5   6   7   8   9   10   11   12