Artists depiction of GRB 080319B Credit: NASA/Swift/Mary Pat Hrybyk-Keith and John Jones

Blinding Gamma Ray Burst Was Directed at Earth

Article Updated: 24 Dec , 2015

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On March 19, 2008 at 2:13 am EDT, NASA’s Swift satellite detected an explosion from the constellation Bootes, and sent an alert to ground-based telescopes. At the same moment, the Russian KONUS instrument on NASA’s Wind satellite and a robotic wide-field optical camera called “Pi of the Sky” in Chile captured the first visible light from this incredibly bright and powerful gamma ray burst. Within the next 15 seconds, the burst brightened enough to be visible in a dark sky to human eyes. For a few moments, the GRB had a million times the luminosity of the entire Milky Way Galaxy. It briefly crested at a magnitude of 5.3 on the astronomical brightness scale. Incredibly, the dying star was 7.5 billion light-years away. Astronomers say the reason this gamma ray burst was so bright was that it was aimed almost directly at Earth.

Observations of the event, formally named GRB 080319B, are giving astronomers the most detailed portrait of a GRB ever recorded. “You have to have the satellites in orbit and the rapid response telescopes on Earth in order take complete advantage this rare kind of event,” said David Burrows, head of the Swift X-ray telescope team, at today’s press conference detailing the GRB.

Judith Racusin of Penn State University and a team of 92 coauthors report on observations across the spectrum that began 30 minutes before the explosion and followed its afterglow for months. The team concludes the burst’s extraordinary brightness arose from an unusual two component jet that shot material directly toward Earth at 99.99995 percent the speed of light.

Telescopes around the world already were studying the afterglow of another burst when GRB 080319B exploded just 10 degrees away.

Immediately after the blast, Swift’s UltraViolet and Optical Telescope and X-Ray Telescope indicated they were effectively blinded. Racusin initially thought something was wrong. Within minutes, however, as reports from other observers arrived, it was clear this was a special event. A head-on burst directed towards Earth only occurs by chance only about once a decade, so GRB 080319B is a rare catch.

Gamma-ray bursts are the universe’s most luminous explosions. Most occur when massive stars run out of nuclear fuel. As a star’s core collapses, it creates a black hole or neutron star that, through processes not fully understood, drive powerful gas jets outward. These jets punch through the collapsing star. As the jets shoot into space, they strike gas previously shed by the star and heat it. That generates bright afterglows.


The team believes the jet directed toward Earth contained an ultra-fast component just 0.4 of a degree across. This core resided within a slightly less energetic jet about 20 times wider. “A normal signature is different from what we saw in this burst,” said Racusin . “In this object, we see two signatures of jets with two different properties.”

“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.”

These unique beacons of light were observed only 8 minutes after the trigger, and are the brightest bursts ever detected. Additional study of this event can also help provide more information on relativity and cosmology.

Burrows said if a similar event happened at our own galaxy, we would be in considerable trouble. “It’s been postulated that a nearby gamma ray burst directed at earth could affect our atmosphere, causing something like a nuclear winter. We are fortunate in that we don’t believe there are any stars in our galas that will produce a gamma ray burst.”

NASA, NASA News Audio


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Dork Leader standing by
Guest
Dork Leader standing by
September 10, 2008 1:00 PM

And the Decepticons used the cover to land their invasion force.

We’re all gonna die!

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Guest
ad
September 10, 2008 2:10 PM

How did they know where Earth was from so far away? Pretty good aiming!

GARY GEORGE
Guest
GARY GEORGE
September 10, 2008 3:19 PM

I WAS UNDER THE UNDERSTANDING THAT A GRB AIMED DIRECTLY AT EARTH WOULD KNOCK OUT ALL COMMUNICATION SATELLITES AND ELECTRICAL GRIDS ETC, WHAT HAPPEN ? OR DID IT TOTALY MISS THE EARTH?

Don Alexander
Member
Don Alexander
September 10, 2008 4:50 PM

Nancy!!!

The KONUS detector is a gamma-ray detector. What you mean is the TORTORA video camera mounted to the REM (Rapid Eye Mount) robotic telescope in La Silla, Chile.

Don Alexander
Member
Don Alexander
September 10, 2008 4:57 PM

“These jets punch through the collapsing star. As the jets shoot into space, they strike gas previously shed by the star and heat it. That generates bright afterglows.”

*sigh*

Seems this falsitude is still being propagated.

Afterglows are created via synchrotron radiation from ultrarelativistic electrons travelling along twisted magnetic fields in shock fronts which are created by the collision. This overpowers any thermal radiation by far.

Don Alexander
Member
Don Alexander
September 10, 2008 5:07 PM

“These unique beacons of light were observed only 8 minutes after the trigger, and are the brightest bursts ever detected.”

And here, we seem to have a mix-up… Optical observations took place DURING the burst, X-ray observations within about 60 seconds. I think the 8 minutes comes from the time it took the VLT to begin observing the optical afterglow spectroscopically, giving us the best spectra ever of a GRB afterglow.

Rey
Guest
Rey
September 10, 2008 5:39 PM

“We are fortunate in that we [b]don’t believe[/b] there are any stars in our galas that will produce a gamma ray burst.”

These are simply human assumptions.

Don Alexander
Member
Don Alexander
September 10, 2008 6:01 PM

@Rey: Backed by an enormous amount of data…

leigh
Guest
leigh
September 10, 2008 6:42 PM

im sure iv seen one once i was looking up at the stars in my garden and one came and went in 5 seconds it was very bright and then just nothing strange i still wonder what it was i saw that night the sky was very clear and full of stars thanks

Quasar9
Guest
September 10, 2008 11:10 PM

the dragon slayer, the eskimo nebula, the smoking star in eta carinea, the GRB from six months ago, and the LHC closer to home – all in one day
The universe isa busy place
and for its next trick, watch this space.

Great blog, love it!

Aodhhan
Member
Aodhhan
September 11, 2008 4:39 AM

Don,

They are referring to the energy and lights caused by the concentrated beams on each end and why they are so bright; which is correct. I believe you are referring to the shock wave which propogates in all directions.

Both right, just describing two different things smile

Eric Near Buffalo
Guest
Eric Near Buffalo
September 11, 2008 6:42 AM

~~leigh Says:
September 10th, 2008 at 6:42 pm
im sure iv seen one once i was looking up at the stars in my garden and one came and went in 5 seconds it was very bright and then just nothing strange i still wonder what it was i saw that night the sky was very clear and full of stars thanks~~

Most likely what you saw was actually a shooting star heading in your general direction – something coming down thru the atmosphere that started burning up and exploded.

leigh
Guest
leigh
September 11, 2008 7:30 AM

iv seen over 100 shooting stars it did not exploded it faded away like you see a star then its gone it was not moving it was still
thanks for the reply leigh

Mike
Guest
Mike
September 11, 2008 7:51 AM

Could have been an Iridium satellite.

Haplo
Guest
Haplo
September 11, 2008 7:12 PM

I told them not to turn on the LHC, now face it! razz

Don Alexander
Member
Don Alexander
September 11, 2008 12:12 PM

@Aodhhan: Nope. At ultrarelativistic speeds, there is almost no sideways movement. Everything is travelling along the direction of the jet – GRBs are invisible from a 90° angle. also, except for the following subrelativistic supernova, the jets are highly collimated, so there is no “in all directions”.

Aodhhan
Member
Aodhhan
September 11, 2008 12:31 PM

Don…

You are misreading what I said, and what NASA is saying as well.

Vern Wall
Guest
Vern Wall
September 15, 2008 3:51 AM

I don’t know much, but I’m told that even a relatively dense concentration of matter in space has only a few particles per cubic kilometer. How is a shock wave produced in such a low density?

Don Alexander
Member
Don Alexander
September 15, 2008 6:58 AM

@Vern Wall: Someone told you wrong. Try “per cubic centimeter”. And while this is still better than almost any vacuum that can be produced on earth, we are talking of HUGE spaces here. This stuff scales, it’s dependent upon the free mean path. While a particle may need to travel 50 AU to collide with another one, you have that space! So collisions and shocks do take place, there’s a speed of sound etc.

Xenophon
Guest
Xenophon
September 15, 2008 7:01 AM

“Incredibly, the dying star was 7.5 billion light-years away. ”

Is this a typo? Our own galaxy is “only” 100 thousand light years across. The nearest galaxy to ours is about 4 million light years distant. The farthest out that Hubble has seen is around 13 billion light years. Something doesn’t add up.

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