For the First Time, Astronomers Have Found a Star That Survived its Companion Exploding as Supernova

A Type II supernova is a truly amazing astronomical event. As with all supernovae, a Type II consists of a star experiencing core collapse at the end of its life cycle and exploding, causing it to shed its outer layers. A subclass of this type is known as Type IIb, which are stars that have been stripped of their hydrogen fuel and undergo collapse because they are no longer able to maintain fusion in their core.

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Not first time. I have heard of this at least once before.

Only slightly off topic, worth repeating here.

The x-axis shows the initial mass of the models and the y-axis the final mass. The different coloured layers show the composition of the star at the moment of collapse. The mass ejected in the supernova is the difference between the curve marked remnant mass, which specifies (for these models) how much matter became part of the remnant, and the final mass, which was the mass of the star at collapse, after it had already lost a lot during its life.

The interesting point in this prediction is the change between the supernovae that leave neutron stars versus those that leave black holes. At the boundary, there’s a large drop in the supernova-ejecta mass, because the black hole doesn’t have a surface off of which inward falling material can bounce.

The relevence to the thread topic is that the smaller the amount of ejected material the more likely a companion star is to survive in orbit. This means that a supernova that generates a black hole is much more likely to keep its companion than one that generates a pulsar. Or to put it another way: the larger the star – the less destructive its supernova is.

mollwollfumble said:

Only slightly off topic, worth repeating here.

The relevence to the thread topic is that the smaller the amount of ejected material the more likely a companion star is to survive in orbit. This means that a supernova that generates a black hole is much more likely to keep its companion than one that generates a pulsar. Or to put it another way: the larger the star – the less destructive its supernova is.

very interesting.

mollwollfumble said:

Not first time. I have heard of this at least once before.

But those were all old supernovas.

“Seventeen years ago, astronomers were fortunate enough to witness a Type IIb supernova in the galaxy NGC 7424, located 40 million light-years away in the southern constellation Grus. Now that this supernova has faded, the Hubble Space Telescope recently captured image of a surviving companion”.

Care is needed to ensure that this is not a supernova imposter like eta carina. Eta carina survived its own supernova. Was there any sign of a progenitor star?