Twins can be close, and that goes for stars as well as people. In some cases, stars get so close that they merge. In an unusual celestial event, astronomers have captured the image of two monster stars that may merge eventually and give us a chance to understand the theory on how supermassive stars are born.
In a paper published in the journal of Astronomy & Astrophysics, Spanish researchers from the Centre of Astrobiology in the University of Alicante, report that two stars in the MY Cam system are in such close proximity that they will end up morphing into a single epically-sized star. The paper observed that the “mergers of high-mass binaries have been proposed as an effective mechanism to form very massive stars”.
The article concludes that MY Cam is the most massive binary star observed and its components, two stars of spectral type O (blue, very hot and bright), 38 and 32 times the Sun’s mass, are still on the main sequence and are very close to each other, with an orbital period of less than 1.2 days, in other words, the shortest orbital period in this type of stars. This indicates that the binary was virtually formed as it is now: the stars were almost in contact at the time they were formed.
The expected development is the merger of both components into a single object over 60 solar masses before any of them have time to evolve significantly. Hence, these results demonstrate the viability of some theoretical models suggesting that most massive stars are formed by merging less massive stars.
It’s not clear how long the merger will take, or what will happen when it does. One possibility is that the merged star will explosively release a vast quantity of energy.
While it won’t create a ‘hypergiant’ star, astrophysicists hope that by seeing the merger of such close binary stars, they can better explain how extremely massive stars form. Hypergiants may be 100 or more times more massive than the sun, and emit hundreds of thousands of times more energy.
Although extreme stars such as these are believed to have been common in the early universe, today they are extremely rare – the entire Milky Way galaxy contains only a handful.
Such discoveries defy the concept that all stars have an upper limit of 150 solar masses. Instead, it is now an accepted fact that if stars are squished together in a densely star-studded environment, they will lose stability and inevitable end up smashing into passing stars to form singular mega-stars.