Star Explosion In The Middle of Nowhere!!

When a shot is fired, one expects to see a person with a gun. In the same way, whenever a giant star explodes, astronomers expect to see a galaxy of stars surrounding the site of the blast. This comes right out of basic astronomy, since almost all stars in our universe belong to galaxies.

But a stellar explosion seen last January has shocked astronomers because when they looked for the star’s parent galaxy, they saw nothing at all. The explosion took place in the middle of nowhere, far away from any detectable galaxy. The astronomers saw no hint of a galaxy even though they looked for one with the world’s largest telescope: the giant Keck I telescope in Hawaii.

"Here we have this very bright burst, yet it's surrounded by darkness on all sides," says Brad Cenko, an astronomer at the California Institute of Technology (Caltech) in Pasadena, Calif. Cenko is the leader of the team that made this discovery. The team includes astronomers from both Caltech and Penn State University.

The explosion belongs to a class of events know as gamma-ray bursts, or GRBs for short. GRBs are triggered when a very heavy star can no longer produce energy. The core of the star implodes to form a black hole — a region of space where gravity is so strong that nothing, not even light, can escape. The black hole spins very fast, producing intense magnetic fields. As inrushing gas from the star spirals toward the black hole, the magnetic fields fling some of the material away from the black hole in two powerful jets. These jets produce the GRB.

Several spacecraft detected the explosion on January 25, 2007. Observations by NASA's Swift satellite pinpointed the explosion, named GRB 070125 for its detection date, to a region of sky in the constellation Gemini. It was one of the brightest bursts of the year, and the Caltech/Penn State team moved quickly to observe the burst’s location with large telescopes on the ground.

Using the team's robotic 60-inch telescope at Palomar Observatory in Calif., the astronomers discovered that the burst had a bright afterglow that was fading fast. They observed the afterglow in detail with two of the world's largest telescopes, the Gemini North telescope and the Keck I telescope, both near the summit of Hawaii's Mauna Kea.

A recent galaxy collision produced the long tail in the Tadpole Galaxy. If GRB 070125 exploded in a similar tail, only Hubble could detect the tail. C redit: NASA, H. Ford, et al.

What came next was a total surprise. Contrary to experience with more than a hundred previous GRBs, The Gemini and Keck observations saw no trace of a galaxy at the burst’s location. "A Keck image could have revealed a very small, faint galaxy at that distance," says team member Derek Fox of Penn State.

So why didn’t the team see a galaxy? One possibility is that the star formed in the outskirts of two galaxies that are colliding. Hubble Space Telescope images of colliding galaxies show that many of them have long star tails that are produced by the gravity of the two galaxies. These tails are very faint, and would not show up in Keck images at the burst’s measured distance from Earth. If this idea is correct, it should be possible to detect the tail by taking a long exposure with Hubble. "That's definitely our next stop," says Cenko.

"Many Swift discoveries have left astronomers scratching their heads in befuddlement," adds Swift lead scientist Neil Gehrels of NASA Goddard Space Flight Center in Greenbelt, Md. "But this discovery of a long GRB with no host galaxy is one of the most perplexing of all."

sources : http://www.nasa.gov/topics/universe/features/intergalatic_shot.html

Mars Glows

WASHINGTON - Mars will be unusually bright this Christmas Eve and the moon will be shining full — a development that might make Santa Claus rethink his need for Rudolph's red nose.

That idea, from Miami Space Transit Planetarium director Jack Horkheimer, made us wonder if retooling a certain reindeer song is the best way to explain it to the kids:

Mars is a red-tinged planet

With a very shiny glow

And if you look to see it

You will find the moon in tow.

The red planet will shine brighter because it will be directly opposite the sun, reflecting the most light, and fairly close to Earth, only 55.5 million miles away. The full moon will appear nearby, rising about an hour later, said Horkheimer, host of the public television show "Star Gazer."

All of the other Yuletides

Santa would have at his side

The shiny nose of Rudolph

Acting as his big sleigh's guide

Mars will outshine the brightest star and won't be as noticeable in the sky for nine more years, Horkheimer said. The Hubble Space Telescope took a picture of Mars, which came closest to Earth on Dec. 18, but it will be brighter on Christmas Eve because of its position opposite the sun.

But this very Christmas Eve

Santa came to say:

"Rudolph, now with Mars so bright,

You can stay at home tonight."

"It will be a brilliant red light," Horkheimer said. "It is so bright it knocks your socks off." He added that this would allow Santa to give Rudolph a pink slip, albeit a temporary one.

Then all the reindeer teased him.

And they shouted out with glee:

"Rudolph, the red-nosed reindeer

Outsourced to astronomy."

About the Black Hole..!!

WASHINGTON - The latest act of senseless violence caught on tape is cosmic in scope: A black hole in a "death star galaxy" blasting a neighboring galaxy with a deadly jet of radiation and energy.A fleet of space and ground telescopes have captured images of this cosmic violence, which people have never witnessed before, according to a new study released Monday by NASA.

"It's like a bully, a black-hole bully punching the nose of a passing galaxy," said astrophysicist Neil deGrasse Tyson, director of the Hayden Planetarium in New York, who wasn't involved in the research.

But ultimately, this could be a deadly punch.

The telescope images show the bully galaxy shooting a stream of deadly radiation particles into the lower section of the other galaxy, which is about one-tenth its size. Both are about 8.2 billion trillion miles from here, orbiting around each other.

The larger galaxy has a multi-digit name but is called the "death star galaxy" by one of the researchers who discovered the galactic bullying, Daniel Evans of the Harvard-Smithsonian Center for Astrophysics.

Tens of millions of stars, including those with orbiting planets, are likely in the path of the deadly jet, said study co-author Martin Hardcastle of the University of Hertfordshire in the United Kingdom.

If Earth were in the way — and it's not — the high-energy particles and radiation of the jet would in a matter of months strip away the planet's protective ozone layer and compress the protective magnetosphere, said Evans. That would then allow the sun and the jet itself to bombard the planet with high-energy particles.

And what would that do life on the planet?

"Decompose it," Tyson said.

"Sterilize it," Evans piped in.

The jet attack is relatively new, in deep space time. Hardcastle estimates it's no more than 1 million years old and can stretch on for another 10 to 100 million years.

"A truly extraordinary act of violence," Evans said. "The jet violently slams into that lower half of the neighboring galaxy after which the jet dramatically twists and bends."

The good news is that eventually an area of hot gas that gets hit and compressed by this mysterious jet — astronomers are still baffled by what's in it and how it works — over millions and billions of years can form stars, Tyson said.

NASA, the National Radio Astronomy Observatory in United States and the University of Manchester in the United Kingdom used ground optical and radio telescopes, the Hubble Space Telescope, the Chandra X-ray Observatory, and the infrared Spitzer Space Telescope to get an image of the violence on various wavelengths, including invisible ones. The results will be published in The Astrophysical Journal next year.

The two galaxies are only 24,000 light-years apart and are in a slow merging process. The jet has already traveled 1 million light-years. A light-year is about 5.88 trillion miles.

Tyson said there are two main lessons to be learned from what the telescopes have found:

"This is a reminder that you are not alone in the universe. You are not isolated. You are not an island."

And "avoid black holes when you can."

source : http://news.yahoo.com/s/ap/20071217/ap_on_sc/death_star