Free Astronomy Magazine May-June 2026

5 ASTRO PUBLISHING suited to probing dusty stellar rem- nants. The data placed important limits on the temperature, composi- tion, and evolution of the material left behind after the star disap- peared, including faint emission from material expelled by the star, helping rule out alternative expla- nations such as an unusual super- nova or intrinsic stellar variability. “It was only with Keck’s sensitivity in the near infrared that we could con- firm the star had truly faded at all wavelengths,” De said. “Even with NIRES, the source was barely de- tected, which allowed us to rule out normal hints of stellar variability or dust obscuration and strengthened the case that the star had genuine- ly disappeared.” The Keck observations were ana- lyzed alongside data from space- based telescopes and other ground- based facilities as part of a coordi- nated, multi-wavelength campaign. Astronomers have long known that black holes originate from massive stars, but direct observational evi- dence of that transformation has been scarce. While gravitational- wave detections have revealed black hole mergers across the uni- verse, they do not show how those black holes initially formed. Only one other candidate direct-col- lapse event has been reported pre- viously, but it was significantly more distant and fainter, leaving its inter- pretation uncertain. The relative proximity of Andromeda and the quality of the available data make M31-2014-DS1 a particularly com- pelling case. “We’ve known that black holes must come from stars,” said Morgan MacLeod, lecturer in astronomy at Harvard University and co-author of the study. “With events like this, we’re getting to watch it happen, and are learning a huge amount about how that process works along the way.” The findings suggest that direct col- lapse may be a more common out- come for massive stars than pre- viously assumed. Future infrared surveys, combined with sensitive ground-based facilities like Keck Observatory, are expected to un- cover additional examples and fur- ther clarify the physical conditions that determine how massive stars end their lives. MAY-JUNE 2026 A shell of thick gas and dust (red) expelled from the outer layers of a star as its core collapsed into a black hole. The inner regions show a heated sphere of gas continuing to fall into the black hole that is hidden inside the hot gas. [Keith Miller, Cal- tech/IPAC – SELab] !