Re: "magnetar" flash of Dec 27th

From: Martin Brown (|||newspam|||_at_nezumi.demon.co.uk)
Date: 03/29/05 

Date: Tue, 29 Mar 2005 08:49:21 +0100

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/scienceastronomy/bright_flash_050218.html

Regards,
Martin Brown

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