<p>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 <a href="https://en.wikipedia.org/wiki/Supernova#Energy_output" rel="nofollow noreferrer">energy released</a> is in the form of neutrinos, which will generally fly straight through the binary partner without impact. </p>

<p>In a <a href="https://en.wikipedia.org/wiki/Type_Ia_supernova" rel="nofollow noreferrer">type 1a supernova</a>, 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.</p>

<p>In addition to <a href="https://astronomy.stackexchange.com/a/27612">Glorfindel's answer</a>, 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 <a href="https://arxiv.org/abs/astro-ph/0305205" rel="nofollow noreferrer">Formation of a Black Hole in the Dark</a>: "The observations suggest that high-mass stellar black holes may form promptly, when massive stars disappear silently."</p>

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

<p><a href="https://physics.stackexchange.com/q/25357">What happens to the neighboring star of a type Ia supernova?</a></p>

<p><a href="https://physics.stackexchange.com/q/30082">Regarding binary systems (with pulsars)</a></p>

CC BY-SA 4.0
2018-09-11T00:27:42.867Z
2018-09-11T00:57:28.943Z
2018-09-11T00:57:28.943Z
Chappo Hasn't Forgotten
<p>There are certain cases where the remaining star survives; this happened to <a href="https://en.wikipedia.org/wiki/X-ray_binary#High-mass_X-ray_binary" rel="nofollow noreferrer">high-mass X-ray binary star systems</a>, 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.</p>

<p>The most famous of these is <a href="https://en.wikipedia.org/wiki/Cygnus_X-1" rel="nofollow noreferrer">Cygnus X-1</a>, the first object widely accepted to be a black hole. The massive star in this pair has the same name as <a href="https://astronomy.stackexchange.com/users/2153/hde-226868">one of our moderators</a>.</p>

CC BY-SA 4.0
2018-09-10T18:58:17.123Z
2018-09-10T18:58:17.123Z
Glorfindel
<p>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?</p>

CC BY-SA 4.0
2018-09-10T16:55:26.630Z
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.
Carl Witthoft
<supernova><binary-star><star-systems>
What happens when a star gets hit by a supernova?
C. Jordan
# What happens when a star gets hit by a supernova?

(Asked by: username_0 on 2018-09-10)

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?

**Tags:** supernova, binary-star, star-systems

> **Comments:**
> **username_1**: 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.  

---

## 2 answers

### Answer by username_2 on 2018-09-11. Score: 2 | Accepted answer

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](https://en.wikipedia.org/wiki/Supernova#Energy_output) is in the form of neutrinos, which will generally fly straight through the binary partner without impact.

In a [type 1a supernova](https://en.wikipedia.org/wiki/Type_Ia_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 [username_3's answer](https://astronomy.stackexchange.com/a/27612), 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](https://arxiv.org/abs/astro-ph/0305205): "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?](https://physics.stackexchange.com/q/25357)

[Regarding binary systems (with pulsars)](https://physics.stackexchange.com/q/30082)


---

### Answer by username_3 on 2018-09-10. Score: 3

There are certain cases where the remaining star survives; this happened to [high-mass X-ray binary star systems](https://en.wikipedia.org/wiki/X-ray_binary#High-mass_X-ray_binary), 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](https://en.wikipedia.org/wiki/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](https://astronomy.stackexchange.com/users/2153/hde-226868).


---

