2024-07-27 23:36:18
An artistic image of a binary system of a red giant star and a younger companion that could merge to produce a blue supergiant. Credit: Casey Reid, NASA
Blue supergiants of type B are luminous and massive stars that defy traditional expectations by often appearing despite their theoretically short evolutionary stage. Recent studies provide new insights, showing that many blue supergiants are likely formed from the merger of massive binary systems. These mergers explain their presence in the “evolutionary gap” and their unique surface characteristics, indicating a significant shift in understanding their lifecycles and their impact on galaxy formation.
Blue supergiants of type B are exceptionally luminous and hot stars, boasting a brightness at least 10,000 times that of the Sun and temperatures that are 2 to 5 times higher. With masses ranging between 16 to 40 times that of the Sun, these stars are believed to exist during a short and rapid phase of star evolution, making them theoretically rare. So why do we see so many of them?
An important clue to their origin lies in the fact that most blue giants are observed as single stars, meaning they do not have a gravitationally bound companion that can be identified. However, most massive young stars are observed as those born in binary systems with companions. Why are blue giants single? The answer: massive binary star systems ‘merge’ and create blue supergiants.
In a groundbreaking study led by IAC researcher Athira Menon, an international team of computational and observational astrophysicists modeled detailed scenarios of star mergers and analyzed a sample of 59 early type B blue giants in the Large Magellanic Cloud, a satellite galaxy of the