To provide a little bit of context for this work, one of the open questions in astronomy is how core collapse supernovae work. Computational scientists have struggled for a long time to get simulations of core collapse to explode. Typically to get an explosion they have to artificially insert a "piston" somewhere in the system that kicks the system outwards during the collapse and triggers the shock wave.<p>Over maybe the last decade or so there's been some thought that if our simulations have trouble getting supernovae to explode, then perhaps nature has trouble getting supernovae to explode, too. Maybe a lot of massive stars just collapse directly into a black hole with no supernova. If this were the case then it would explain a discrepancy between the observed supernova rate and the total number of black holes; there seems to be about twice as many black holes as there are supernovae.<p>When I was in grad school one of the ongoing projects in my department was the so-called "Survey about Nothing" in which they took deep images of nearby galaxies and waited to see if any bright stars just... disappeared. (They did find one candidate: <a href="https://arxiv.org/abs/1411.1761" rel="nofollow">https://arxiv.org/abs/1411.1761</a>)<p>The authors in this paper find another star that just disappeared. The trouble with all this is that if a star disappears it's unclear what exactly happened. Maybe it collapsed into a black hole, or maybe it just temporarily shrouded itself in dust and will be back in a few decades. The new thing about this star is that they have detailed spectra of the star prior to its disappearance, which helps tremendously with modeling the star. The hope is that with more detailed measurements they might be able to place limits on what is currently there and thereby figure out if a direct collapse happened or not.