This may sound like a strange question, but say that two stars are relatively next to one another in a binary star system, what would happen to one of the stars if the other went supernova? Would it explode as well, or would it survive the blast?

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    $\begingroup$ Interesting question - but be warned that a lot of different factors affect the outcome. A supernova can grow to a rather large diameter, but will have a relatively low energy density compared with the partner star - even tho' that energy density is enough to kill anything vaguely alive. $\endgroup$ Commented Sep 10, 2018 at 16:55

2 Answers 2


There are certain cases where the remaining star survives; this happened to high-mass X-ray binary star systems, pairs which consist of a neutron star or black hole (the remnant of a supernova) and a massive star. The X-rays are produced when some of the material ejected by the star is captured by the supernova remnant.

The most famous of these is Cygnus X-1, the first object widely accepted to be a black hole. The massive star in this pair has the same name as one of our moderators.


Remember that although a supernova expels a huge amount of matter, this matter travels outwards in all directions and only a tiny fraction of it impacts on the binary partner. In the case of a core collapse supernova, the vast majority of the energy released is in the form of neutrinos, which will generally fly straight through the binary partner without impact.

In a type 1a supernova, most of the released energy is kinetic. However, as the exploding star is completely disrupted, this "kicks" the other star out of the system (think of swinging a ball on a string in a circle around you, and you suddenly relax your grip on the string), so it's not hanging around for the shock wave. Since this is travelling at 5,000-20,000 km/s, it will eventually (within a few hours) catch up with the escaping star, but will have become substantially attenuated by then.

In addition to Glorfindel's answer, it's worth noting that where the remnant partner of a high-mass X-ray binary is a black hole, it's likely that the progenitor star was also high-mass and collapsed directly to singularity, without a significant explosion. As Felix Mirabel and Irapuan Rodrigues note in Formation of a Black Hole in the Dark: "The observations suggest that high-mass stellar black holes may form promptly, when massive stars disappear silently."

You might also be interested in the answers to these questions on our sibling site [Physics.SE]:

What happens to the neighboring star of a type Ia supernova?

Regarding binary systems (with pulsars)

  • $\begingroup$ Thank you for that amount of info, it is quite interesting $\endgroup$
    – C. Jordan
    Commented Sep 13, 2018 at 13:37

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