Gamma ray bursts: Start here

[Astroman]

Just checking. I'll add more, (some?) later. Meanwhile, any specific questions?

[OXO]

How would you describe a Gamma Ray Burst to someone with no real sence of the idea?

James

[AndyMac]

How would you describe a Gamma Ray Burst to someone with no real sence of the idea?

James

....or even "sense of the idea"!

[OXO]

Dyslexia Rule's :twisted:

James

[Astroman]

I'd describe a GRB as the largest explosion imaginable. For some scale-the bomb dropped on Hiroshima contained about 50 Kg of fissionable material, of which about 0.5 Kg was turned into energy. Modern thermonuclear weapons will turn roughly 10 Kg into energy. A GRB, if radiating in all directions as with a supernova, would turn the equivalent mass of our Sun into energy. Scary. Fortunately for us, these explosions take place billions of light years away and our atmosphere and magnetosphere do a wonderful job of shielding us from the effects. Also, new evidence is that they don't radiate in all directions, (isotropically), but "beam" their energy along a relatively narrow path. This means that they're less energetic, but that we don't see them all either.

[AndyMac]

Interesting opening statement Astroman.

I've read that the light from a GRB can last anything from a fraction of a second to several seconds & that, on average, about one is visible per day (correct me if I'm wrong, of course).

Does your average amateur astronomer have any chance of seeing a GRB from a dark sky site, realistically?

[Ant]

How close would GRB have to be to us for it to become a problem? 10Ly's a 100?

Ant

[Astroman]

Andy: It depends on how you define "light". The gamma rays may last from milliseconds to several minutes. Radio, at the other end of the spectrum, is generally delayed, sometimes by weeks, and can last for a month. Visible light can be nondetectable or last a matter of hours or days.

A gamma ray detection of one per day is about average, but occurrences may be more often. Actual observations in all wavelengths tend to be negative, depending on the nature of the beast. (There are two basic types-short/hard and long/soft, categorized by active time and spectrum. Hard being x-rays and above, soft being x-rays and below.)

The chances of observing a GRB by chance is essentially nil. The brightest optical afterglow known reached 9th magnitude but faded to 12th mag in a few minutes. It was caught accidentally by a robotic camera setup in New Mexico. GRB optical afterglows generally start at 13th mag and fade within hours to 17th mag, if visible at all. That's the challenge! You have to get on it QUICKLY to see it at all. But, amateurs are uniquely suited for impromptu observations, being unconstrained by paying customers, as the pros tend to be.

Ant: GRB's have had effects on our magnetosphere by measurable amounts already. Fortunately, there are no deliterious effects. To do any "real damage", they'd have to be quite close-probably within 100 Ly. Since there are no objects of sufficient mass to produce one within this range, you can rest easy. The nearest GRB so far was measured through redshift at 1 billion light years, back in 1999, I think. It was associated with a supernova and relatively low energy.

I really do hope to write something up this week. I'll do my best, (which is negligable, sadly). :roll:

[OXO]

Astroman i heard that our own planet creates is own version of GRB's is this true? and in what way are they produced?..

James :roll:

[Astroman]

Astroman i heard that our own planet creates is own version of GRB's is this true? and in what way are they produced?..

Weeell, not quite. The heating of the Earth's core is due to radioactive decaying elements, and so iS detectable as background radiation. Sporadic increases in activity can occur depending on the density of material, and interaction with other elements and even cosmic rays. A "burst" from the Earth is really an issue of scale. Terrestrial bursts may be tens of ergs/cm^2. Galactic bursts are truly enormous, as stated before.

[Astroman]

James: I just remembered, while beginning the GRB write-up, that the BATSE instrument aboard the Compton Gamma Ray Observatory satellite, (CGRO) did detect gamma ray bursts from Earth. Not nearly of the energy of cosmic events, but significant. They appeared to come from strong thunderstorms. Indeed, events called "Sprites" and "Blue jets" sometimes emanate from the tops of very strong thunderstorms as a kind of "anti-lightning" strike. They've been seen from space, high altitude jets and from the ground when the storms are distant. No explanation has thus far been satisfactory, though there are a few theories. Google it, and let us know what you find, ok? 8)

[OXO]

Thanks Astroman.. I will have a search later tonight funny thing is those sprite's featured in a CRank UFO video my friend payed me to watch. There was a recorded view from the ISS showing the sprite blasting out into space No dought there will be some dung around when i search the net eh Astroman lol

James

[Astroman]

Dung on the internet? Surely not! >cough, gag< :twisted:

[Astroman]

As I said, I'm writing up a thing on GRB's, but it's getting kind of long. Any thoughts on size limits? Hard restrictions on post limits? Split it up into bite-sized chunks, maybe?

[OXO]

Astroman if you could split it up a little that would be good plus your post count would grow even higher although there's no limit to the size of post certainly not from me anyway dont know if the forum's structure can take it though lol.....

Looking forward to the post's.

James

[AndyMac]

James, unlike you I suspect that Astroman isn't arsed about the size of his post count!

He prefers quality over quantity!

I agree with James - probably bite-size chunks would be better. S'long as you keep posting.