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Starburst Was One of Brightest Objects Observed on Earth
NY Times ^ | February 18, 2005 | KENNETH CHANG

Posted on 02/18/2005 9:31:11 PM PST by neverdem

For a fraction of a second in December, a dying remnant of an exploded star let out a burst of light that outshone the Milky Way's other half-trillion stars combined, astronomers announced today.

Even on Earth, half a galaxy away, the starburst was one of the brightest objects ever observed in the sky, after the Sun and perhaps a few comets. The magnitude of the event caught most astronomers by surprise.

"Whoppingly bright," said Dr. Brian Gaensler, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "It gave off more energy in 0.2 seconds than the Sun does in 100,000 to 200,000 years."

No one on Earth directly saw the flare, because most of the light was gamma rays, photons that are more energetic than X-rays and are blocked by the atmosphere. But the Dec. 27 pulse registered on instruments aboard 15 spacecraft, including NASA's new Swift satellite, which was designed to record cosmic gamma rays and had been turned on just the week before.

Dr. Neil Gehrels, the lead scientist for Swift, said flares of that magnitude could be expected just once in a millennium. "That seems so improbable it's a puzzle right now," he said. "There's something going on here that we don't understand."

The radiation also pushed in the Earth's ionosphere, an envelope of charged gas at the top of the atmosphere, and distorted long-wavelength radio signals.

"It was really the big one," said Dr. Kevin Hurley, a researcher at the Space Sciences Laboratory at the University of California, Berkeley. "You could not have missed it."

Astronomers pinpointed the origin of the pulse as a neutron star known as SGR 1806-20, about 50,000 light-years distant in the constellation Sagittarius. Neutron stars are remnants of stars after they have exploded in supernovas, and SGR 1806-20 is one of about 10 unusual neutron stars known as magnetars, which have extraordinarily strong magnetic fields, a quadrillion times as strong as Earth's.

Sudden shifts in the intense magnetic fields are believed to generate flares, in much the way the Sun generates solar flares, and two giant magnetar flares had been observed previously, one in 1979 and one in 1998. The Dec. 27 flare, however, was 100 times as powerful.

One physicist, Dr. David Eichler of Ben-Gurion University in Israel, wrote a paper in 2002 suggesting that magnetars might be capable of such cataclysmic explosions, but for most scientists, Dr. Gaensler said, "we had no idea they could make a flare this big." SGR 1806-20 has as much mass as 1.5 Suns, compressed into an incredibly dense ball about a dozen miles wide, and it spins around once every 7.5 seconds, which is slow for a neutron star. Discovered in 1979, SGR 1806-20 has at times been noisy, firing off small gamma ray flares, and at other times quiet. Its activity picked in the past year.

"In retrospect, I guess you could say it was getting ready to let go," Dr. Hurley said, adding that the magnetic fields, held in place by the crust of the star, had become twisted, building stress. "At some point, it gives way like an earthquake," he said.

Astronomers presented their observations at a NASA news conference today, and two scientific papers describing the event will be published in an upcoming issue of the journal Nature.

In the aftermath of the flare, Dr. Gaensler, lead author of one of the Nature papers, and his colleagues used radio telescopes on Earth to track a shock wave radiating outward from the star. They were surprised to find the bubble expanding at a third of the speed of light. "Which is not what you tend to see in the galaxy every day," he said.

SGR 1806-20 itself continues to spin as before, one revolution every 7.5 seconds.

"Amazingly, the neutron star is still there," Dr. Gaensler said. "It did not explode or blow itself apart to bits."

The magnetar flare might help solve a cosmic mystery of gamma ray bursts, the prime mission of the Swift satellite. Bursts lasting for minutes are believed to be caused by the collisions of black holes - events that are even more violent than magnetar flares, which occur much farther away - but astronomers had been at a loss to explain shorter bursts lasting a couple of seconds or less.

Now they have at least a partial answer: some of the bursts are magnetar flares originating from other galaxies.

"It is clear magnetar flares make short gamma ray bursts," said Dr. Robert C. Duncan of the University of Texas. "It is at least a significant fraction of them."

However, that still may not be whole answer. Dr. Gehrels said that when astronomers looked in the direction of three recent short gamma ray bursts, those parts of the sky turned out empty.

"It just all fits so well and then there were no galaxies there," Dr. Gehrels said. But he said that as Swift observes more gamma ray bursts, "We should know in the next couple of months the answer to this."

TOPICS: Culture/Society; Government; News/Current Events; Technical; US: District of Columbia; US: Florida
KEYWORDS: magnetar; nasa; starburst
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To: neverdem
The dimmest object ever observed on Earth:

... and the widest object ever observed on Earth:

21 posted on 02/18/2005 11:35:27 PM PST by thoughtomator (If Islam is a religion, so is Liberal!)
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To: neverdem

I'll read it tomorrow. I just read:

Starbucks Was One of Brightest Objects Observed on Earth

It's 2:30

22 posted on 02/18/2005 11:39:17 PM PST by Recall
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To: neverdem

It was really done to fool the Cylons...

23 posted on 02/18/2005 11:42:33 PM PST by WestVirginiaRebel ("Senator, we can have this discussion in any way that you would like.")
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To: neverdem
Here's a picture!

24 posted on 02/19/2005 1:11:47 AM PST by ThreeYearLurker
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To: neverdem

Since the object in question is 50 thousand light years away, the December event is a "delayed report" of an event at the object 50 thousand years ago (supposing that the speed of light in a vacuum really is constant over time).

Likely there are many other "delayed reports" out there. For all we know, the center of our galaxy detonated thousands of years ago and will, in due course, sweep away our world entirely. It's due for something like that anyway (2Pet3:10-13), although the timing is obscure.

25 posted on 02/19/2005 2:13:38 AM PST by Blue_Ridge_Mtn_Geek
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To: neverdem
This was posted twice before, the first time with the NASA title:
Cosmic Explosion Among the Brightest in Recorded History; and the someone posted it a second time, using some other title:
Brightest Galactic Flash Ever Detected Hits Earth.
26 posted on 02/19/2005 4:30:30 AM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)
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To: King Prout
dead star went boom.

It's fallen and it can't get up.

27 posted on 02/19/2005 8:05:33 AM PST by jriemer (We are a Republic not a Democracy)
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To: neverdem
It's called SGR 1806-20 and is in the constellation Sagittarius, which is abbreviated SGR, so I thought the designation must be from its location until I read that SGR means "soft gamma repeater." Good thing it wasn't a hard gamma repeater.

Its magnetic field is a quadrillion times that of earth. We're talking serious numbers here--one quadrillion is 1000 times one trillion.

Meanwhile, today is the birthday of Nicolaus Copernicus, the founder of modern astronomy.

28 posted on 02/19/2005 8:09:10 AM PST by Verginius Rufus
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To: neverdem

This happened just before or just after the big tsunami?

29 posted on 02/19/2005 8:09:42 AM PST by Amelia
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To: neverdem

As I've been saying for years, this is the main reason why we should not transport White Castles cheeseburgers into the sun.

30 posted on 02/19/2005 8:39:55 AM PST by P.O.E.
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To: PatrickHenry

The NASA news release was linked in the first comment. I find that it's interesting to have more than one perspective. Thank's for the other link.

31 posted on 02/19/2005 9:47:21 AM PST by neverdem (May you be in heaven a half hour before the devil knows that you're dead.)
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To: Ernest_at_the_Beach
From the article you linked: Another clue to the pulsar/magnetar difference may lie in how fast neutron stars are spinning when they form. Gaensler and his team suggest that heavy stars will form neutron stars spinning at up to 500-1000 times per second. Such rapid rotation should power a dynamo and generate superstrong magnetic fields. 'Normal' neutron stars are born spinning at only 50-100 times per second, preventing the dynamo from working and leaving them with a magnetic field 1000 times weaker, says Gaensler.

HA! I knew there was something weird about that rotation rate!. Thanks for the link Ernest.

32 posted on 02/19/2005 10:49:09 AM PST by zeugma (Come to the Dark Side...... We have cookies! (Made from the finest girlscouts!))
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To: zeugma
The bigger those stars are , the more they have magical properties. If you haven't read thru all of that link at post #17, try to find the time, it is quite good. The Universe is an astounding place. A great Book Reference is 100 Billion Suns, although it is somewhat dated, nothing about Magnetars, as I recall. My Son has my copy, so I can't check.
33 posted on 02/19/2005 11:09:34 AM PST by Ernest_at_the_Beach (A Proud member of Free Republic ~~The New Face of the Fourth Estate since 1996.)
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To: neverdem

Makes me wonder what's the possibility of a star exploding nearby and causing massive comm failure worldwide.

34 posted on 02/19/2005 2:26:41 PM PST by Bogey78O (Hillary Clinton + Fertility pills + Scott Peterson + rowboat = Success)
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To: thoughtomator

I hear Moore is much fatter. His mass is so huge though it distorts his true appearance.

35 posted on 02/19/2005 2:28:11 PM PST by Bogey78O (Hillary Clinton + Fertility pills + Scott Peterson + rowboat = Success)
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To: Bogey78O
Makes me wonder what's the possibility of a star exploding nearby and causing massive comm failure worldwide.

If by expoding star you mean a supernova, there are three likely candidates nearby, astronomically speaking: Betelgeuse in Orion, Antares in Scorpio and Ras Algethi in Hercules. They are 430, 600 and 380 light years away, respectively.

Chances of one of those three becoming a supernova in the near future seem slim.

Someone more knowledgeable than me will have to address the subject of communications disruptions.

The visual effect would be stunning: image a pinpoint of light brighter than the aggregate light of the full moon --but not as bright as the sun.

There is an interesting discussion of supernovae at this web site:

36 posted on 02/19/2005 4:49:05 PM PST by ngc6656
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To: ngc6656

Ever since I stopped studying astronomy in junior high it's all greek to me.

37 posted on 02/19/2005 8:26:33 PM PST by Bogey78O (*tagline removed per request*)
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To: Ernest_at_the_Beach; KevinDavis

thanks E for the ping.

38 posted on 02/20/2005 2:01:20 PM PST by SunkenCiv ("Are you an over due book? Because you've got FINE written all over you!")
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Comment #39 Removed by Moderator

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