[ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

Tue Sep 9 13:22:19 CDT 2014

That could also be a profound example of the basic principle that the universe is pretty much the same all over. One reading of the history of science is that it's a continuing series of discoveries that show that our part of the universe is nothing special - we're not at the center of the solar system, or of the galaxy, or of the universe. In fact, pretty much anyplace we look in the universe it looks more or less the same. Not only that, but as near as we can tell, the laws of physics that Newton, Einstein, and so many others have elucidated here on Earth seem to hold equally well out to the billions of light years we can see - distant in time as well as in place. So your friend's saying that, behind a distant cluster of galaxies, things look pretty much like they do anywhere else can be a fairly profound statement about the universe.

Incidentally, some physicists studied the distribution of decay products in the Oklo reactor (about 2 billion years old) and concluded that the laws of radioactive decay - and all of the related physical constants and laws - seem to have remained constant over that time period. And the light curves from distant supernovae confirm that Co-56 and Ni-56 behave just the same in galaxies halfway across the universe as they do in our cosmic neighborhood.

Cool stuff!

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Brennan, Mike (DOH)
Sent: Tuesday, September 09, 2014 12:15 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

I can just see the report of a universe-ending chain-supernova event being recalled when they discover it was really a school of amorous lantern fish.

One of my astrophysicist friends was telling me about using gravitational lensing from distant galaxies to see what is behind them, and when I asked what they saw he said, "Oh, pretty much what we see everywhere else."  Seems like a lot of trouble to go through to see mostly nothing.

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of KARAM, PHILIP
Sent: Tuesday, September 09, 2014 8:58 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

They do indeed. I was at a supernova conference in 2007 to give a paper and one of the talks was about the challenges involved in building a 1000 cubic km neutrino telescope in the deep ocean off Hawaii. Apparently they're looking at putting an array of highly sensitive photo-multiplier tubes to look for scintillation from neutrinos striking water molecules - similar to the array they have set up in the Antarctic ice cap.

P. Andrew Karam, PhD, CHP
NYPD Counterterrorism
One Police Plaza, Room 1109
New York, NY 10038
(718) 615-7055 (desk)
(646) 879-5268 (mobile)

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Brennan, Mike (DOH)
Sent: Tuesday, September 09, 2014 11:48 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

I read something similar about neutrinos; if you were close enough to get a significant neutrino dose the ordinary operation of the star would have already killed you, let alone the supernova.  

I also read a discussion (not a published paper) that argued it isn't the dust and gas of the core that shields, but given the number and close spacing of the stars in the core, it is a near certainty that that there would be a star in the direct line of sight, and a star should be enough shielding for anybody's purposes.  This is even more true if, as some theories hold, at the center of each galaxy there is a super-massive black hole.

All of this led me to the conclusion that astrophysicist deal in some weird stuff. 

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of KARAM, PHILIP
Sent: Tuesday, September 09, 2014 7:13 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

I remember looking at this as well - a high-energy gamma ray burst in the Andromeda galaxy (about 3 million light-years away) could actually expose an astronaut here to about a rad (10 mGy). 

There was some speculation in the late 1990s that periodic gamma ray bursts might explain why we haven't been contacted by alien civilizations yet - wondering if they periodically cause galaxy-wide mass extinctions. That seems dubious, given that even a "long" gamma ray burst only lasts a few seconds - enough to sterilize half a planet, but not the whole thing. Plus, the thick dust and gas clouds in the galactic core would help to shield the opposite side of the galaxy from the worst effects (although normal dust and gas clouds in the disk are so scanty as to offer very little in the way of attenuation).

There was also some speculation that neutrinos from supernovae might cause mass extinctions - there are about 10^57 neutrinos produced during the collapse of a giant star into a neutron star. But the interaction cross-section of SN-spectrum neutrinos is too small and, even with one very nearby, the dose would be too small to cause health problems. Interestingly, the biggest concern from a nearby supernova will likely be ozone depletion and the formation of opaque chemicals in the atmosphere. Some astronomers in Texas (Scalo an Wheeler) suggested that a climate-altering supernova might occur close enough to have a measurable impact every 10,000-100,000 years.

Andy 

P. Andrew Karam, PhD, CHP
NYPD Counterterrorism
One Police Plaza, Room 1109
New York, NY 10038
(718) 615-7055 (desk)
(646) 879-5268 (mobile)

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Brennan, Mike (DOH)
Sent: Monday, September 08, 2014 5:56 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

Some time ago an astrophysicist friend of mine sent me some numbers for the output of gamma ray bursts, and possible effects on the crew of the International Space Station.  I don't remember the numbers, but if the source was in our galaxy, and the Earth was in the beam, it would be bad.  As to the Space Station, I couldn't tell if the exposure would kill the crew outright, or if they would hold on long enough die from complete failure of every system on station.  The effects on the surface of the planet wouldn't be good, either.  

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of KARAM, PHILIP
Sent: Monday, September 08, 2014 12:45 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

Yep! Due to shielding by the supernova remnant only about 10% of the gamma radiation escapes into space, and that's over the space of a year.  I calculated that a supernovae would be close enough to Earth to give a sea-level dose of 1 Sv about once every 10 million years or so. But to get a lethal dose of radiation in a short period of time you'd have to be pretty close and think it's safe to say that the radiation wouldn't be what killed you.

Andy

P. Andrew Karam, PhD, CHP
NYPD Counterterrorism
One Police Plaza, Room 1109
New York, NY 10038
(718) 615-7055 (desk)
(646) 879-5268 (mobile)

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Brennan, Mike (DOH)
Sent: Monday, September 08, 2014 11:40 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

As I understand it, if you are close enough to a supernova that the gamma is significant, you have other fairly pressing concerns.

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of KARAM, PHILIP
Sent: Monday, September 08, 2014 7:18 AM
To: ROY HERREN; The International Radiation Protection (Health Physics) Mailing List; Radsafe
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

Supernovae produce about a solar mass (10^30 kg) of Co-56, which decays to Ni-56, and thence to Fe-56. The total amount of gamma energy released by the decay of the Co-56 and Ni-56 to stability is more than 10^49 ergs. I wrote a paper on this topic - along with the attenuation of the gamma dose by the supernova remnant and radiation dose to nearby stars and planets - in 2002; I believe it appeared in Radiation Physics and Chemistry.

http://www.sciencedirect.com/science/article/pii/S0969806X01004546

Cool stuff!

Andy

P. Andrew Karam, PhD, CHP
NYPD Counterterrorism
One Police Plaza, Room 1109
New York, NY 10038
(718) 615-7055 (desk)
(646) 879-5268 (mobile)

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of ROY HERREN
Sent: Monday, September 01, 2014 12:21 AM
To: Radsafe
Subject: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

http://mipt.ru/en/news/astrophysicists_report_radioactive_cobalt_in_supernova_explosion

Astrophysicists Report Radioactive Cobalt in Supernova Explosion

Roy Herren
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