Science Now

The observations reveal that the jets of the gamma-ray burst called GRB 080319B were aimed almost directly at the Earth.

2008-09-11T05:34:00.000-07:00

Astronomers from around the world combined data from ground- and space-based telescopes to paint a detailed portrait of the brightest explosion ever seen. The observations reveal that the jets of the gamma-ray burst called GRB 080319B were aimed almost directly at the Earth.
GRB 080319B was so intense that, despite happening halfway across the Universe, it could have been seen briefly with the unaided eye (ESO 08/08). In a paper to appear in the 11 September issue of Nature, Judith Racusin of Penn State University, Pennsylvania (USA), and a team of 92 co-authors report observations across the electromagnetic spectrum that began 30 minutes before the explosion and followed it for months afterwards.
“We conclude that the burst's extraordinary brightness arose from a jet that shot material almost directly towards Earth at almost the speed of light – the difference is only 1 part in 20 000,” says Guido Chincarini, a member of the team.
Gamma-ray bursts are the Universe's most luminous explosions. Most occur when massive stars run out of fuel. As a star collapses, it creates a black hole or neutron star that, through processes not fully understood, drives powerful gas jets outward. As the jets shoot into space, they strike gas previously shed by the star and heat it, thereby generating bright afterglows.
The team believes the jet directed toward Earth contained an ultra-fast component just 0.4 degrees across (this is slightly smaller than the apparent size of the Full Moon). This jet is contained within another slightly less energetic jet about 20 times wider.
The broad component is more typical of other bursts. “Perhaps every gamma-ray burst has a narrow jet, but astronomers miss it most of the time,” says team member Stefano Covino. “We happened to view this monster down the barrel of the very narrow and energetic jet, and the chance for this nearly head-on alignment to occur is only about once a decade,” added his colleague Cristiano Guidorzi.
GRB 080319B was detected by the NASA/STFC/ASI Swift satellite towards the constellation of Boötes, the ”Herdsman”. A host of ground-based telescopes reacted promptly to study this new object in the sky, including ESO’s Very Large Telescope, which was the first to provide the distance of the object, 7.5 billion light-years. The visible light from the burst was detected by a handful of wide-field cameras worldwide that are mounted on telescopes constantly monitoring a large fraction of the sky. One of these was the TORTORA camera mounted on the 0.6-m REM telescope at ESO’s La Silla Observatory (ESO 26/07).
TORTORA’s rapid imaging provides the most detailed look yet at the visible light associated with the initial blast of a gamma-ray burst. "We've been waiting a long time for this one," says TORTORA senior scientist Grigory Beskin of Russia's Special Astrophysical Observatory. The data collected simultaneously by TORTORA and the Swift satellite allowed astronomers to explain the properties of this burst.

[From sciencedaily]

The world's largest particle collider successfully completed its first major test.

2008-09-10T04:30:00.000-07:00

The world's largest particle collider successfully completed its first major test by firing a beam of protons all the way around a 17-mile (27-kilometer) tunnel Wednesday in what scientists hope is the next great step to understanding the makeup of the universe.

After a series of trial runs, two white dots flashed on a computer screen at 10:36 a.m. (0836 GMT) indicating that the protons had traveled the full length of the US$3.8 billion Large Hadron Collider.

"There it is," project leader Lyn Evans said when the beam completed its lap.

Champagne corks popped in labs as far away as Chicago, where contributing scientists watched the proceedings by satellite. Physicists around the world now have much greater power than ever before to smash the components of atoms together in attempts to see how they are made.

"Well done everybody," said Robert Aymar, director-general of the European Organization for Nuclear Research, to cheers from the assembled scientists in the collider's control room at the Swiss-French border.

The organization, known by its French acronym CERN, began firing the protons — a type of subatomic particle — around the tunnel in stages less than an hour earlier.

Now that the beam has been successfully tested in clockwise direction, CERN plans to send it counterclockwise. Eventually two beams will be fired in opposite directions with the aim of recreating conditions a split second after the big bang, which scientists theorize was the massive explosion that created the universe.

The start of the collider — described as the biggest physics experiment in history — comes over the objections of some skeptics who fear the collision of protons could eventually imperil the earth.

The skeptics theorized that a byproduct of the collisions could be micro black holes, subatomic versions of collapsed stars whose gravity is so strong they can suck in planets and other stars.

"It's nonsense," said James Gillies, chief spokesman for CERN, before Wednesday's start.

CERN is backed by leading scientists like Britain's Stephen Hawking in dismissing the fears and declaring the experiments to be absolutely safe.

Gillies told the AP that the most dangerous thing that could happen would be if a beam at full power were to go out of control, and that would only damage the accelerator itself and burrow into the rock around the tunnel.

Nothing of the sort occurred Wednesday, though accelerator is still probably a year away from full power.

"On Wednesday we start small," said Gillies. "A really good result would be to have the other beam going around, too, because once you've got a beam around once in both directions you know that there is no show-stopper."

The project organized by the 20 European member nations of CERN has attracted researchers from 80 nations. Some 1,200 are from the United States, an observer country which contributed US$531 million. Japan, another observer, also is a major contributor.

The collider is designed to push the proton beam close to the speed of light, whizzing 11,000 times a second around the tunnel.

Smaller colliders have been used for decades to study the makeup of the atom. Less than 100 years ago scientists thought protons and neutrons were the smallest components of an atom's nucleus, but in stages since then experiments have shown they were made of still smaller quarks and gluons and that there were other forces and particles.

The CERN experiments could reveal more about "dark matter," antimatter and possibly hidden dimensions of space and time. It could also find evidence of the hypothetical particle — the Higgs boson — believed to give mass to all other particles, and thus to matter that makes up the universe.

Some scientists have been waiting for 20 years to use the LHC.

Top 10 NASA Space Photos, the renowned orbiting telescope whose discoveries have forever altered our knowledge (Pics)

2008-09-09T08:26:00.000-07:00