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(This question was originally posted via World Building, but I was instructed to post it here) https://worldbuilding.stackexchange.com/questions/109457/is-a-supernova-powerful-to-destroy-the-other-star-in-a-binary-system?noredirect=1#comment332775_109457

The question is basically the same:

Can a binary star system have one of the two stars go supernova in the first place, and if so:

The first scenario would be:

  • Star A of the binary swells to red giant status, and then is either touching or consumes star B: what would happen?

Scenario 2:

  • Star A goes supernova, with maybe 1 AU of distance between it and Star B.

What info Id like to know:

  • Can it destroy the other star via supernova?
  • What is the effective range of the supernova, and can it destroy stars a light year or more away?
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  • $\begingroup$ It's best to ask one question per question on Stack Exchange sites. OTOH, why do you even mention scenario 1? The red giant phase happens in the middle of a star's life, a long time before any kind of supernova can occur. BTW, there are various types of supernova, but they all require a large star, a star with the mass of our Sun can't go supernova. $\endgroup$
    – PM 2Ring
    Apr 13, 2018 at 14:44
  • $\begingroup$ OTOH, you can have a binary system where the heavier star goes red giant and then eventually becomes a white dwarf. When the lighter star goes red giant the white dwarf can pull matter from the red giant, and that can lead to nova explosions, or if it pulls enough matter you can get a type Ia supernova. See en.wikipedia.org/wiki/Type_Ia_supernova $\endgroup$
    – PM 2Ring
    Apr 13, 2018 at 15:16
  • $\begingroup$ @PM i mention Red Giant because the original premise is that the stars lifecycle is being artifically accelerated to an extreme degree. I mentioned 1 solar mass because typically people request that I add some sort of baseline to my question $\endgroup$
    – Razmode
    Apr 13, 2018 at 15:35
  • $\begingroup$ Ok, if you can accelerate time in the star's core that may also allow you to get around the mass restriction. But it does make it hard to give a scientifically accurate answer when you bring in SciFi elements like that, and we like our answers here to be science, not SciFi. ;) $\endgroup$
    – PM 2Ring
    Apr 13, 2018 at 15:52
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    $\begingroup$ Understood. I guess we can tell you about real supernovae here, and let you extrapolate. :) $\endgroup$
    – PM 2Ring
    Apr 13, 2018 at 16:30

2 Answers 2

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The gravitational binding energy of a solar mass star of uniform density is $3GM^2/5R = 2.2774\times 10^{41}$ Joule. The energy of a typical supernova is $10^{44}$ J. So it looks at first glance like the explosion could disperse the other star...

...except that this assumes more than a thousandth of the supernova energy is absorbed and does work on the star. If the other star is more than 16 stellar radii away then it will definitely not be hit by this much energy. And even if it is close enough, converting radiation to mass lift is not going to be efficient. The nova will mainly heat up the surface layer down a few optical depths, meaning a few thousand kilometers get very hot but it is doubtful this does more than push the star away a bit and induces some wobble.

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  • $\begingroup$ So at a distance of say, 3 AU it won't do much? $\endgroup$
    – Razmode
    Apr 13, 2018 at 22:36
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    $\begingroup$ @Raznarok - Yes, I would be surprised if it did any damage. Of course "damage" is relative. Stars are pretty robust things, so losing a bit of the atmosphere or having it heated a lot will not change the basic hydrodynamic equilibrium enormously. $\endgroup$ Apr 13, 2018 at 22:40
  • $\begingroup$ To be clear, you mean $10^{44}$ J of electromagnetic and kinetic energy? The total energy released in a type II supernova is $\sim 10^{46}$ J, but mostly in neutrinos. $\endgroup$
    – ProfRob
    May 23 at 7:42
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Yes, and it is common that only one star in a binary system goes SN at a time. Besides that, merger that results in SN-like event is also possible.

The first scenario: this is a bit more complicated than you might think. When a star expands, its material reaches Lagrangian point where the material beyond this point is transferred to its companion. The consequence of this depends on parameters. It might end as SN Ia if the companion is white dwarf, or black hole if it is neutron star, etc. Meaning that its companion might not be "consumed." The case of "consumed" is, if I understand your intention correctly, called common envelope. Normally, common envelope evolution ends at merging. Complication is likely possible.

Scenario 2: Normally, a SN in binary system (at real physical distance) cannot even significantly blow its companion to leave the vicinity (that is why people try to search for possible companion in the vicinity after observing SNe). So, a SN cannot "destroy" its companion. Speaking of that, I don't know for certain the answer to the hypothesized distance of 1AU. For a light year away, that is for certain the explosion will not destroy its companion.

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