# How could events triggered by a supernova accelerate the death of a main sequence star?

My story revolves around a star going supernova. The 'Earth' in this story is about 100 light-years or more away (a safe distance, but not too far away). I need this supernova to somehow accelerate the death of this 'Earth''s star such that it will slowly become uninhabitable in the next 1 million years.

In Asimov's novel, streams of interstellar matter rich in different elements affect stellar lifetime. Later, learning about catalytic fusion processes, that made sense. Except that the dominant form of power production in a small star like the sun is not the catalytic kind, the amount of material in space is much too small, the interstellar mediumm stays out of the bubble made by the sun, and solar wind blows away from the star.

Something produced in core-collapse supernova moreso than electromagnetic radiation is neutrinos. Gamma ray bursts are beamed not by focusing the light but by channeling the material that then produces the light. So wouldn't neutrinos also be beamed? That's how neutrinos are made in beams in accellerators: the neutrino will be travelling in the same direction as what produced it, when that is greater than the momentum given to the neutrino in its production.

So a burst of neutrinos hits the solar system, causing all sorts of problems but also giving the sun indigestion. A burst of excess power in the dense core will take a long time to work through the layers, and will blow the top of the mantle off when it reaches a shalow enough depth.

Heliosismology tracks the whole process.

• Ooh! Neutrinos, I thought they were generally harmless. I mean, loads of them pass through the Earth all the time to no effect right? Nevertheless, its science fiction, with the emphasis on fiction, so great, this gives me enough to work with. :) – Isabella Chen May 12 '15 at 11:40
• @IsabellaChen If you like the answer hit the little up arrow to give it a vote, and if it answers your question hit the little check mark. It is generally a good idea to wait at least a day or two before choosing an answer to encourage others to contribute. Welcome to Worldbuilding! (If you knew all this already then just ignore me :) – AndyD273 May 12 '15 at 14:00
• Yes, neutrinos are generally harmless. But a core-collapse supernova generates more energy in the form of neutrinos than light. It's incomprehensible how high the flux is. Rare events on that scale will deposit a significant amount of energy. Also, the density of the sun's core and the technobabble resonance can be used. – JDługosz May 12 '15 at 21:55

They're fine.

Here, I discussed the effects of a supernova on life on Earth. Note that a supernova would have to be within about ten parsecs (~33 light-years) to have harmful effects on life on Earth. Furthermore, the effects would be indirect, destroying the ozone layer (partially or in full) rather than incinerating the planet. At 100 light-years, we're fine.

On to your actual question. The lifetime, $\tau$, of a star on the main sequence is approximately $$\tau=10^{10}\text{ years} \cdot \left[\frac{M}{M_{\odot}} \right]^{-2.5}$$ where $M$ is the mass of the star and $M_{\odot}$ is the mass of the Sun. From this, we can see that a star with more mass will spend less time on the main sequence.

So you need to add mass to the "Sun", and you need to add mass that can be used for nuclear fusion. I can get you specific data for the density of a supernova remnant, which you could use to figure out to amount of material in a given area near the "Sun", but I think it's safe to say that there will not be a significant amount of material useful for fusion anywhere near the "Sun".

• Thanks, that gave me something to work with. This has to be explained to a 10 year old girl in the book, at an early stage of discovering that the sun is dying, so an answer to the girl like, "The sun is becoming heavier due to the supernova, which means it will die sooner. We didn't expect this to happen because we can't see enough material from the supernova near the Sun, but it is. We'll find out why..." Of course if there's other possible reasons, however far-fetched... I'd love to hear them... – Isabella Chen May 10 '15 at 19:34
• Oh, how about Gamma ray bursts? Could they possibly in any way affect the Sun? – Isabella Chen May 10 '15 at 20:31
• @IsabellaChen I think there are posts somewhere here that touch on that, but the answer is most likely the same as for supernovae: No. Except even more so. – HDE 226868 May 10 '15 at 20:53
• Yea, but some interesting room for hand-waving. See my answer post. :) – JDługosz May 11 '15 at 9:24
• There could be enough material nearby, but then I don't think there would be any people nearby to worry about it. – KSmarts May 11 '15 at 17:05