An international ensemble of astronomers led by the Canary Institute for Astrophysics has unraveled how some of the brightest and hottest stars in the cosmos, the blue B-type supergiants, come into being. The findings were published in a leading journal that reports on astrophysical discoveries, Astrophysical Journal Letters.
Blue B-type supergiants stand out for their exceptional luminosity and extreme temperatures. Their masses span from roughly 16 to 40 solar masses, making them at least 10,000 times brighter than the Sun and typically 2 to 5 times hotter. For many years, scientists explored why such stellar beacons exist and why they appear with notable frequency in certain regions of the universe, yet the precise routes of their formation remained puzzling.
Researchers built sophisticated models of star formation and compared them with a vast data set from the Large Magellanic Cloud, a nearby satellite galaxy of the Milky Way. The analysis provided strong evidence that a majority of blue supergiants may arise when two stars in a bound pair merge into a single, more massive object. The merger scenario accounts for the rapid energy output and the distinctive surface properties observed in these stars during a substantial portion of their evolution.
In explaining the mechanism, the team highlighted how the interaction and mixing of material during a close encounter or collision can dramatically alter the evolving stars. The simulations tracked evolved giant stars as they interact with smaller companions across a broad range of conditions. Once the merger occurs, the newborn star maintains the blue supergiant phase through much of its second evolutionary stage, continuing until helium begins to exhaust in its core and the star transitions to later phases of stellar life. The study credits the insights to researchers at the IAC, including contribution from Athira Menon, who is cited as a key author in the work.
Looking ahead, the researchers plan to examine how blue supergiants engage with compact objects such as neutron stars and black holes. These future efforts aim to illuminate whether binary interactions can influence the fate of blue supergiants, including potential end states such as exotic compact remnants or explosive outcomes. The research team also intends to refine the statistical framework and incorporate additional observational data to test the merger hypothesis across different galactic environments.
Previously, astronomers had clarified the mystery surrounding the unusually rapid rotation observed in red supergiants such as Betelgeuse, shedding light on how angular momentum can be redistributed during late-stage stellar evolution. These parallel findings help piece together a cohesive picture of how massive stars evolve, interact, and enrich their surroundings with the heavy elements produced in their interiors. The ongoing investigation into blue supergiants adds a crucial chapter to this broader narrative of stellar life cycles and the dynamic processes that sculpt the brightest minds of the night sky.