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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
And the Decepticons used the cover to land their invasion force.
We’re all gonna die!
How did they know where Earth was from so far away? Pretty good aiming!
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?
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.
“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.
“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.
“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.
@Rey: Backed by an enormous amount of data…
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
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!
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 🙂
~~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.
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
Could have been an Iridium satellite.
I told them not to turn on the LHC, now face it! 😛
@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”.
Don…
You are misreading what I said, and what NASA is saying as well.
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?
@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.
“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.
The article was correct:
http://apod.nasa.gov/apod/ap080328.html
” The source of that burst has been discovered to lie over halfway across the Universe at a distance of about 7.5 billion light-years. Now holding the distinction of the most distant object that could be seen by the unaided eye and the intrinsically brightest object ever detected”
@Xenophon: The nearest galaxy is more like 2 million light years away. As for Hubble, it wasn’t looking in the Milky Way as Burrows said (apologies for the entire quote): ‘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.” ‘
Moreover, if the Hubble’s limit is 13 billion light years, then 7.5 billion is within reach for the Hubble to detect. What is it that doesn’t add up? Perhaps… the wording in the article?
‘
A GRB traveled 7.5 billion light-years in a direction that
allowed wonderful observations from Earth and satellites.
How could that have been “aimed” or “directed” toward an
Earth that would not exist for another ~3 billion years?
From the article:
Covino: “… down the barrel of the … jet.”
Burrows: “… postulated that a nearby GRB directed at earth …”
NA: … aimed almost directly at Earth.
NA: … shot material directly toward Earth …
NA: A head-on burst directed towards Earth …
NA: The team believes the jet directed toward Earth …
Perhaps a future version of this writeup could use
constructions that does not imply intent or foreknowledge,
such as “in the direction of” or “jet that travelled toward
Earth’s current location”, rather than risking readers taking
“aimed” and “directed towards” as clear evidence of the
FSM’s far-reaching and all-knowing powers and capabilities.
help out here seem to be a little lost with the usage of the present tense you made seem like the burst just occured inspite of that great distance of 7.5 billion light years away i would presume that burst occured alittle 7.5 billion years ago more in respect to the seep of the gamma rays 99.9999…… am right ?
The road of assumption is lined with coffins.
your diagram is too small. the wording cannot be made out even if we click the diagram and see if it expands.
I had a GRB once after eating at Taco Bell
“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.””
So THAT’S what killed the dinosaurs! I always thought the “big rock falling from the sky” theory was a bit silly….
@ GRaBoid –
You got the impression that the article was saying this was purposely ‘aimed’ ? That strikes me as odd !
And yes, if it’s 7.5 billion light years away, that means it happened 7.5 billion years ago. The Sun wasn’t even a twinkle in the eye of cold interstellar gas.
Just some brief comments:
It may have been aimed in that direction, where Earth is now; however, neither our planet existed then- event ocurred before it’s creation-, nor was our planet- then- where it is now, thus it is not feasible for GRB to have been “aimed” at our planet. One can be just a tad more realistic and see that the GRB ocurred as part of it’s process, and by shear “luck, we have been in the path of one of it’s lines of travel, we can be realistic, hopeful, and with our feet solidly on the ground, and then we can evaluate things with more coherence, which allows us to see with more clarity any and all events that happen out there. Thank you. Javier
re Leigh, 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~”
Back about Sept 2000 in the southerly direction of the Southern Cross (am in Australia) I saw a similar event in the sky to that you describe but which lasted for about 20sec before fading & was very bright similar to other stars around it if not brighter if I recall correctly (long ago now). It illuminated to maximum brightness quickly, caught my attention, was steady in brightness & without motion & I remember thinking it couldn’t possibly be a meteor & looked as though it was there to stay but then faded away.
I assumed it may have been a supernova at the time but didn’t know what to do about it or who to call etc. & assumed somebody more important than a casual observer would have spotted it. I would like to know more about what it may have been if anybody knows of such an event around that time & location. I think I could reconstruct more detail as the event stuck in my mind thats for sure & made a good mental note of it, time, date, approximate location in the sky. Trouble is I thought that if it was something very far away then even a small amount area of sky is still a huge area. Regret not following up at the time now.
Re comments about “aimed” etc. – Guys don’t get your knickers in a knot 🙂 – I think we all know it wasn’t actually “aimed” how stupid do you think we are…..& if you actually are that stupid to believe it was “aimed” well may the force be with you and keep you safe, warp 10 Scotty! 😉 Cheers.
It’s amazing to realize how little we understand. For example the velocity of our sun relative to the black hole at the center of our galaxy. There are too many vectors to be taken into consideration. Even for an entire planet of astrophysicists.
It’s amazing to me that most comments are splitting hairs over the common usage of the word “AIMED” ….
Wow, it’s amazing at what can happen in the Universe.