Astronomers have been looking for the wrong kind of stars to see them turn into black holes; they aren't red, they're 'hot blue.'
April 17, 2026
Original Paper
Hot blue progenitors of stellar-mass black holes
arXiv · 2604.12868
The Takeaway
For years, the hunt for 'disappearing stars'—massive stars that collapse directly into black holes without a supernova explosion—has focused on 'red supergiants.' This study shows that's a mistake: most black hole 'parents' are actually hot, blue 'Wolf-Rayet' stars. Because these stars are so hot and bright in the blue spectrum, we’ve been looking in the wrong 'color' for decades. This explains why we’ve found so few of these events; they were hiding in plain sight in a different part of the light spectrum. This discovery is like realizing you've been looking for a missing person in the woods when they were actually at a bright, neon dance club the whole time.
From the abstract
While the connection between massive stars and supernova explosions is well established observationally, the link between massive stars and black hole formation remains elusive. Some massive stars may collapse directly to black holes without a successful supernova, and may therefore appear as disappearing stars. We investigate the expected photometric properties of such black hole progenitors by combining detailed single and binary stellar evolution models with physically motivated prescriptions