"magnetar" flash of Dec 27th

I've just read about this unusual star and the gigantic pulse it emitted,
with the strength of a weak dental x-ray outside the atmosphere. I have two
questions: 1) How would the "flash" have appeared on the ground had it
encountered Earth's night side and 2) even though the article sort of
downplays radiation exposure levels, what would the radiation levels be say
100 l.y. away from this star and would the radiation have penetrated an
atmosphere on a planet like ours at that 100 l.y. distance?

Juan

Juan Pederson wrote:
I've just read about this unusual star and the gigantic pulse it emitted,
with the strength of a weak dental x-ray outside the atmosphere.

Some reports put it even brighter in the hard X-ray to gamma wavebands.

I have two
questions: 1) How would the "flash" have appeared on the ground had it
encountered Earth's night side

Only indirectly if at all by the changes it caused in ionisation of the
upper atmosphere. Radio propogation altered and more sky glow.

and 2) even though the article sort of
downplays radiation exposure levels, what would the radiation levels be say
100 l.y. away from this star and would the radiation have penetrated an
atmosphere on a planet like ours at that 100 l.y. distance?

They seem to reckon at 10ly it would be very bad for the Earth. Luckily
there are none that close to us. The Earth's atmosphere is a very good
radiation shield - very little ionising radiation gets through it!

Reasonable article on it at:
http://www.space.com/scienceastronom...sh_050218.html

Regards,
Martin Brown

On Tue, 29 Mar 2005 08:49:21 +0100, Martin Brown
wrote:

Juan Pederson wrote:
I've just read about this unusual star and the gigantic pulse it emitted,
with the strength of a weak dental x-ray outside the atmosphere.

Some reports put it even brighter in the hard X-ray to gamma wavebands.

I have two
questions: 1) How would the "flash" have appeared on the ground had it
encountered Earth's night side

Only indirectly if at all by the changes it caused in ionisation of the
upper atmosphere. Radio propogation altered and more sky glow.

and 2) even though the article sort of
downplays radiation exposure levels, what would the radiation levels be say
100 l.y. away from this star and would the radiation have penetrated an
atmosphere on a planet like ours at that 100 l.y. distance?

They seem to reckon at 10ly it would be very bad for the Earth. Luckily
there are none that close to us. The Earth's atmosphere is a very good
radiation shield - very little ionising radiation gets through it!

Radiation is governed by the inverse square law so it's amazing at
a distance of 10ly that it would pose a threat. Kind of begs the
question; In tight star clusters with a lot of blue stars, would
life be possible at all?
-Rich

RichA wrote:
On Tue, 29 Mar 2005 08:49:21 +0100, Martin Brown
wrote:


Juan Pederson wrote:

I've just read about this unusual star and the gigantic pulse it emitted,
with the strength of a weak dental x-ray outside the atmosphere.

Some reports put it even brighter in the hard X-ray to gamma wavebands.


I have two
questions: 1) How would the "flash" have appeared on the ground had it
encountered Earth's night side

Only indirectly if at all by the changes it caused in ionisation of the
upper atmosphere. Radio propogation altered and more sky glow.

and 2) even though the article sort of

downplays radiation exposure levels, what would the radiation levels be say
100 l.y. away from this star and would the radiation have penetrated an
atmosphere on a planet like ours at that 100 l.y. distance?

They seem to reckon at 10ly it would be very bad for the Earth. Luckily
there are none that close to us. The Earth's atmosphere is a very good
radiation shield - very little ionising radiation gets through it!


Radiation is governed by the inverse square law so it's amazing at
a distance of 10ly that it would pose a threat. Kind of begs the
question; In tight star clusters with a lot of blue stars, would
life be possible at all?

A lot of life exists deeper than 100 m under water on Earth, that's a
lot of shielding. Some speculate that deep sea hydrothermal vents could
have been the original site of life here. Lots of possibilities besides
the anthropocentric terrestrial one.

Shawn