Astronomers have observed a massive star in the Andromeda Galaxy undergoing a direct collapse into a black hole, bypassing the typical supernova explosion. Designated M31-2014-DS1, this star exhibited a significant increase in mid-infrared brightness in 2014, maintaining this luminosity for approximately 1,000 days before fading dramatically over the next 1,000 days. By 2023, it was no longer detectable in deep optical and near-infrared observations. This pattern of behavior is inconsistent with known variable stars, suggesting an alternative explanation.
Researchers estimate that M31-2014-DS1 had an initial mass of about 20 times that of the Sun, which reduced to approximately 6.7 solar masses by the end of its nuclear-burning phase. Observations indicate the presence of a recently ejected dust shell surrounding the star, a feature typically associated with supernova events. However, the absence of any detected optical outburst implies that the star underwent a "failed" supernova, leading directly to the formation of a black hole without the characteristic explosion.
This phenomenon challenges the conventional understanding of stellar evolution, particularly the processes leading to supernovae and black hole formation. The findings suggest that certain massive stars may collapse into black holes without a supernova explosion, a scenario that has been theorized but rarely observed. This discovery provides valuable insights into the life cycles of massive stars and the mechanisms underlying black hole formation, highlighting the need for further research into these complex astrophysical processes.
Resource: Kishalay De et al, The disappearance of a massive star marking the birth of a black hole in M31, arXiv (2024). DOI: 10.48550/arxiv.2410.14778
