Super Nova Explosions Force at 1AU

eburacum45 · Post #21by **eburacum45** » 05.12.2006, 06:50

If you are in a calculating mood, Malenfant, you might like to work out if such a force would be sufficient to entirely dismantle an Earth sized planet.
Since planets do exist around pulsars I expect some worlds at least do survive the experience...

Malenfant · Post #22by **Malenfant** » 05.12.2006, 06:58

eburacum45 wrote:If you are in a calculating mood, Malenfant, you might like to work out if such a force would be sufficient to entirely dismantle an Earth sized planet.

Ugh, no thanks, it gave me enough of a headache last time...

Since planets do exist around pulsars I expect some worlds at least do survive the experience...

I thought those planets were supposed to have formed from debris leftover after the supernova explosion? The ones around PSR B1257+12 are orbiting within 1 AU of the neutron star, so either they formed in situ there after the supernova or they're rocky remnant cores of gas giants that came before that spiralled in to those orbits afterwards... but they're too close to have been original planets because they'd have been consumed in the star's supergiant phase.

Hungry4info · Post #23by **Hungry4info** » 05.12.2006, 23:55

Malenfant wrote:I calculated this all out for a brown dwarf orbiting Antares at a distance of 2000 AU and the system was toast even out there. And when the actual blast wave hits (I've just been talking about the increased luminosity so far, not the physical blastwave of material blown out from the star), you're going to get the equivalent of several megatons equivalent of TNT hitting per square metre of area of planet.

Could you please share how/what you do/did to derive that? I'm sure you take into account the mass of the star, it's radius, the semi-major axis, and all that, but I'm not all to good at mathematics.

eburacum45 · Post #24by **eburacum45** » 06.12.2006, 04:19

Malenfant wrote:I thought those planets were supposed to have formed from debris leftover after the supernova explosion? The ones around PSR B1257+12 are orbiting within 1 AU of the neutron star, so either they formed in situ there after the supernova or they're rocky remnant cores of gas giants that came before that spiralled in to those orbits afterwards... but they're too close to have been original planets because they'd have been consumed in the star's supergiant phase.

Good point. This page has a nice graphic showing a dusty disk around a pulsar; looks like new planets could easily form from such a disk (even allowing for the typical exaggeration most graphic artists seem to employ when depicting dust disks)
http://science.nasa.gov/headlines/y2006 ... lanets.htm

MKruer · Post #25by **MKruer** » 06.12.2006, 06:41

I guess my next question in as ?€?what if?€

eburacum45 · Post #26by **eburacum45** » 09.12.2006, 11:27

I have never heard of a supernova causing another nearby star to go supernova. It is possible, I suppose that material from a supernova would fall onto a white dwarf and cause a secondary explosion of some sort- you probably wouldn't want to hide behind a white dwarf in such a situation.
Even an ordinary star must be affected by a very close supernova; some binary stars are very close, and if the second star was heated by the explosion, it would surely increase in luminosity on one face at the very least. If you were hiding behind the star you would have a certain amount of time before the second star rotated its new, hot face towards you.

Has anyone seen any speculation concerning the effects of a supernova on a close binary?

Cygnus X-1 for example was a close binary pair before the explosion of one component; what happened to the second component when the explosion occured, I wonder?

ajtribick · Post #27by **ajtribick** » 09.12.2006, 11:46

PSR B1257+12 is a millisecond pulsar, which suggests that something occurred to spin it up to such fast rotation. This makes the idea that the planets are remnants of an original planetary system, and the idea that they formed from the supernova debris, seem unlikely. A more likely scenario is that they formed from the destruction of a ~0.016 solar mass companion, which could also have been responsible for the spin-up of the pulsar.

The population of black-widow pulsars

eburacum45 · Post #28by **eburacum45** » 10.12.2006, 11:17

So those worlds might be gas giants made from the remnants of a shredded star? Fascinating.
0.016M Sol is quite a small star, though, isn't it. A brown dwarf rather than a star proper, I believe.

Hungry4info · Post #29by **Hungry4info** » 06.01.2007, 23:59

Hungry4info wrote:Could you please share how/what you do/did to derive that? I'm sure you take into account the mass of the star, it's radius, the semi-major axis, and all that, but I'm not all to good at mathematics.

Anybody?

MKruer · Post #30by **MKruer** » 28.07.2007, 06:17

Sorry to dreg up this topic again. But I would like to know how to figure this out. I am revisiting some of my old topics.

Originally I though that a super nova blew up in more of a shell configuration, but it seems to me that for all intents I could use just an increasing sphere of matter were the density of matter diminishes as the sphere expands. If this is true, then all I need to know is the density of matter, the temperature at the density, and I can figure out what the fall off is for the explosion, and at what distance a planet might be able to survive.

cyber_space_doc · Post #31by **cyber_space_doc** » 28.07.2007, 13:56

I expect an inverse square law would probably be appropriate. Something like

p2 = p1 / R^2

where p2 is the density at the distance R, and p1 is the density at the surface.

The explosion would be very destructive even at great distances from the star. A good example of a destructive explosion is a Volcanic Eruption. Even a low mass volcanic pyroclastic cloud can destroy an entire city. Wikkipedia puts the percentage of volcanic ash in the air at about 0.1 to 1% during a surge.

http://en.wikipedia.org/wiki/Pyroclastic_surge

After a supernova I would think that there would still be clouds of superhot material expanding throught space.

MKruer · Post #32by **MKruer** » 28.07.2007, 17:43

If I did my math right, using our sun under going a supernova explosion, someone would need to be approximately ~620 times further away from the star in its normal state when a supernova occurred, to experience the same thermal output as when the star was originally there.

This does not account for the blast wave, which depending of the source is traveling between 3-23c

So if somehow you managed to survive the initial flash behind an object, you would still only have only hours before the blast wave hit and destroyed the object or weeks if you were distance enough.

julesstoop · Post #33by **julesstoop** » 28.07.2007, 18:38

But I don't think the thermal output of the initial flash is your biggest problem, it's more probably the amount of highly energetic radiation (gamma, x-ray).

bigbadspike · Post #34by **bigbadspike** » 28.11.2007, 03:51

That's almost unimaginable. Imagine a force that is many thousand times more powerful than the Hiroshima nuke being unleashed on every square metre of the planet's surface that faced the star!! It's mind-boggling!

I wonder how far away such an event would have to be to strip away a good deal of the atmosphere, weaken the magnetic field and maybe boil an ocean?

ajtribick · Post #35by **ajtribick** » 28.11.2007, 09:07

A simple calculation shows that the mass loss associated with the supernova would result in the orbits becoming unbound (the neutron star mass of about 1.4 solar masses, versus the progenitor of >~10 solar masses, means that more than half of the system's total mass is lost)*. So the planets end up flying off into space. This is another reason the pulsar planets are unlikely to be remnants of pre-supernova worlds.

* This situation can be recovered by invoking a supernova kick to the neutron star, which if in the right magnitude and direction could leave a bound system, but it is highly unlikely to save multiple planets in this way.