# Do all massive stars explode?

I've read a few articles written in $2008$ that some stars which have enough mass just collapse into black holes without a supernova, is this proven?

• Failed supernovae are certainly possible, but the jury is still out on black holes emerging anyway: arxiv.org/abs/1609.01283 – called2voyage Apr 19 '17 at 20:41
• There are hypothesis about supernovas that were in such massive stars that the outer layers contained the blast, yet a black hole still formed in the middle. They might have been stable for a few million years even. I just saw this video yesterday talking about it. They don't have a definitive answer either, but it is a little more information about the topic. – Cody Apr 19 '17 at 23:58

There are a variety of models of stars collapsing into black holes without proper supernova explosions. These are often called failed supernovae or direct collapse black holes - although the former seems more common. Failed supernovae can happen if the initial shock wave rebounding from a collapse loses enough energy, causing it to fizzle out. Neutrinos produced in the core often supply this energy, but a small enough burst may not be enough to keep the shock going. There might then be a simple collapse.

The minimum mass for the progenitor of a failed supernova is unknown (and as Rob Jeffries pointed out, this is metallicity-dependent). Some early models (e.g. Fryer (1999)) found that stars above $40M_{\odot}$ could produced failed supernovae, while newer ones suggest that this could be as low as $25M_{\odot}$. This lower limit would include a sizable portion of red supergiants - which could be a possible solution to the red supergiant problem.

A number of searches, largely targeting supergiants, have been carried out. Just a few are

So far, we have no definite confirmation that these stars were failed supernovae. However, they do seem plausible candidates, and there are many more possibilities out there. One group proposed monitoring one million supergiants in an attempt to catch failed supernovae. Perhaps they'll be successful.

• The recent detection of gravitational wave sources makes the production of 30 solar mass black holes necessary. These are unlikely to be produced in supernovae I think. Also worth mentioning that the direct collapse events are more likely in low-metallicity objects. – Rob Jeffries Apr 20 '17 at 12:02
• JPL just posted a few days ago a new article on N6946-BH1 and failed supernovae in general. It claims that as many as 30 percent of stars 25 solar masses or greater may collapse into black holes sans supernova. – called2voyage May 30 '17 at 19:23
• @called2voyage That's interesting; I'll have to read that. – HDE 226868 May 31 '17 at 14:52