Nearby supernova risk discussed by Sigurdsson

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Discussion Overview

The discussion revolves around the potential risks posed by the supernova T Pyxidis, particularly its distance from Earth and the implications of its eventual explosion. Participants explore various aspects of supernova types, their effects on the atmosphere, and the reliability of current information regarding T Pyxidis.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants note that T Pyxidis is approximately 1000 parsecs (or about 3260 light years) away, suggesting it is not a material threat to Earth.
  • Others reference media claims that T Pyxidis could potentially damage the ozone layer, but express skepticism about the validity of these claims at such a distance.
  • A participant argues that a supernova would need to be much closer (within 100 light years) to cause significant atmospheric damage through gamma rays.
  • There is mention of the energy output differences between T Pyxidis (a Type Ia supernova) and SN1054 (a Type II supernova), with calculations suggesting that SN1054 was significantly more powerful.
  • Some participants express uncertainty about the potential effects of T Pyxidis, indicating that more research is needed to understand the implications fully.
  • Concerns are raised about the media's portrayal of the situation, with some participants suggesting that sensationalism may lead to unnecessary fear.
  • One participant discusses the conditions under which a supernova could emit a gamma-ray burst and the limited range of such effects, emphasizing the complexity of the phenomena involved.

Areas of Agreement / Disagreement

Participants generally agree that T Pyxidis is not an immediate threat due to its distance, but there is disagreement regarding the potential effects of a supernova on Earth's atmosphere and the reliability of media reports. The discussion remains unresolved on the specifics of the risks involved.

Contextual Notes

Participants highlight limitations in current understanding and the need for further confirmation of claims regarding T Pyxidis. There are also discussions about the assumptions underlying the calculations of energy output and atmospheric effects.

marcus
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The preprint on this has not come out yet. What we have is a 5 January blog entry by Sigurdsson.
http://scienceblogs.com/catdynamics/2010/01/has_a_supernova_type_ia_progen.php

The work concerns T Pyxidis
and is by a group at Villanova University led by Prof. Edward Sion.

What I get from this is that T Pyxidis is extremely interesting but far enough away not to pose a material threat to Earth.

The explosion they think T Pyxidis is preparing for for is type Ia.
 
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I read about this today in an online German magazine. T Pyxidis is something like 1000 ly away, IIRC. The German article described it as a "death star" that "some astronomers feared would destroy the ozone layer". I had read that a GRB was dangerous at that distance if it was pointed at us, but I didn't think that a SN could damage the ozone from three hundred parsecs.
 
Arch2008 said:
I read about this today in an online German magazine. T Pyxidis is something like 1000 ly away, IIRC. The German article described it as a "death star" that "some astronomers feared would destroy the ozone layer". I had read that a GRB was dangerous at that distance if it was pointed at us, but I didn't think that a SN could damage the ozone from three hundred parsecs.

My information is not 1000 ly, but more like 1000 parsec.
In other words around 3260 light year.

I suppose, like your German article said, it COULD pose a threat to our ozone layer, by the gammaray causing nitrogen and oxygen in our atmosphere to react to form the oxide NO, which would then eat our ozone.

But the impression I get is that we don't even have a reliable understanding and also the current reports need to be confirmed. So there is no reason for concern. We still must find out more and understand more.

I'm curious to see the German article. if not too much trouble could you give a link?
 
There is no way in hell, even if the supernova produced a GRB aimed down our throats, that a supernova 3260 ly distant will have ANY effect. The Earth would need to be struck by a GRB within no more than a hundred or so ly to really do massive damage. That damage would come in the form, mostly, of portions of the upper atmosphere being converted to nitric oxide and causing catastrophic climate change. For a really great article by NASA, try this: http://earthobservatory.nasa.gov/Newsroom/view.php?id=22898
 
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The NY Daily News loves hot headlines as much as any rag, but they are quoting Edward Sion as saying that "soon" means about 10 million years.

http://www.nydailynews.com/news/world/2010/01/05/2010-01-05_possible_supernova_could_threaten_earth_say_astronomers.html
 
turbo-1 said:
The NY Daily News loves hot headlines as much as any rag, but they are quoting Edward Sion as saying that "soon" means about 10 million years.

http://www.nydailynews.com/news/world/2010/01/05/2010-01-05_possible_supernova_could_threaten_earth_say_astronomers.html

Well... that's pretty soon in a cosmic sense. LOL... oh man, that article is so funny. I think people have become fear-junkies.
 
Frame Dragger said:
There is no way in hell, even if the supernova produced a GRB aimed down our throats, that a supernova 3260 ly distant will have ANY effect. The Earth would need to be struck by a GRB within no more than a hundred or so ly to really do massive damage. That damage would come in the form, mostly, of portions of the upper atmosphere being converted to nitric oxide and causing catastrophic climate change. For a really great article by NASA, try this: http://earthobservatory.nasa.gov/Newsroom/view.php?id=22898
Well I'd be interested in the calculations. For comparison, the year http://en.wikipedia.org/wiki/SN_1054" was day light visible and was 6300 ly away. Assuming the explosions have similar energies, we should receive, what, 4X the energy on Earth from a T Pyxidis explosion? Even if not a photon or particle of ionizing radiation penetrated the atmosphere, might not a 4X SN1054 be worth another Watt or two on top our current 1366W? Or, might it wreck the night/day biological cycles for a while? What is the likely energy release from a T Pyxidis super nova, as compared to SN1054?

Also, this pop press article cites Sion, Godon and McClain of AAS saying T Pyxidis is already overdue, clear the building.
http://www.thesun.co.uk/sol/homepage/news/2795981/Supernova-may-wipe-out-the-Earth.html
 
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More reading shows that T Pyxidis would be a Type IA, yielding 1–2 × 10^44 joules over 10s per http://en.wikipedia.org/wiki/Supernova#Type_II", and SN1054 was a Type II supernova (9 solar masses) which yields 10^46 joules. Assuming this wiki swag is correct, SN1054 was 50-100x more powerful than T Pyxidis could hope to be, thus all is well and nothing to see here, please disperse. :confused:

https://www.youtube.com/watch?v=<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/rSjK2Oqrgic&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/rSjK2Oqrgic&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>
 
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  • #10
mheslep said:
More reading shows that T Pyxidis would be a Type IA, yielding 1–2 × 10^44 joules over 10s per http://en.wikipedia.org/wiki/Supernova#Type_II", and SN1054 was a Type II supernova (9 solar masses) which yields 10^46 joules. Assuming this wiki swag is correct, SN1054 was 50-100x more powerful than T Pyxidis could hope to be, thus all is well and nothing to see here, please disperse. :confused:

This is... yes. Well keep in mind that the power of a supernova has a lot to do with (as you've discovered) the type which is determined by the star's initial mass (when it first was a star so to speak), and its composition when it gravity overwhelmes everything up to and including nuclear forces.

The scenario in which we (people on Earth! lol) have to be concerned requires a vast star collapsing to form a neutron star (or some other more degenerate form of matter) or black hole. In that scenario you could find that when the star collapses it emits a large Gamma Ray Burst (think of extragalactic jets, but a lot briefer and far more energetic) and THAT, which is radiated in two cones from two poles. Even then, the range for a change in atmospheric conditions is within a hundred or hundreds of ly, not thousands.

Finally, this all illustrates another major issue: dying stars do not emit the energy you are talking about in a perfectly homogeneous sphere. This can lead to danger for us (by letting a GRB extend the 'range' of such an event in relation to Earth), but it also means that much of what you might expect to reach a distant object is lost to the remnant (nebula, neutron star, black hole, etc), material ejecta which poses no risk, and high energy gamma rays... but concentrated into (relatively narrow) cones.

For the record however, ANY event that bombards Earth with gamma rays (such as the ongoing existence of Sol) which falls short of converting our ozone layer into a layer of Nitric Oxide would probably just cause some very interesting lightshows. Our atmosphere makes for a dandy shield, which is why we can live within such close proximity to Sol.
 
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