In the Large Magellanic Cloud galaxy is a star-forming region that has puzzled astronomers around the world for years. It is called the Tarantula Nebula and it is an object so luminous that, if it were at the same distance from Earth as the Orion Nebula, it would even cast shadows on our planet.
This luminosity is due to the presence of four supermassive stars of enormous dimensions that were discovered in 2010 by a team of researchers. These four giant suns baffled the scientific community, which until now considered that the most massive stars could reach, at most, 150 times the mass of our sun . But the four stars of the Tarantula Nebula increase it up to 300 times, something that dismantled all theories. Would the model of star formation that was taken for granted until now be invalid?
A group of researchers from the University of Bonn has just demonstrated the formation process of these four supermassive stars using computer simulations. To the astronomers’ relief, the theory complies perfectly with hitherto known mechanisms.
The explanation, published in the Monthly Notices of the Royal Astronomical Society , is relatively straightforward: the four monstrous suns were formed by multiple collisions of smaller massive stars .
The simplest explanation is usually the correct one
The researchers simulated an initial cluster with more than 170,000 normally distributed stars. As they are relatively ‘tight’, as time passes, collisions between pairs of stars occur, until in the end, stars of enormous mass are obtained. “Imagine two very bulky stars that orbit very close to each other but are separated by the gravitational pull of neighboring stars . If their initial circular orbit is stretched far enough, then the stars collide with each other as they pass, causing a single ultramassive star “, explained Sambaran Banerjee, one of the authors.
It seems, therefore, that the mystery is solved. “This makes us breathe easy,” said Pavel Kroupa, another author. “The collisions imply that supermassive stars are easy to explain, and that the universality of star formation prevails above all else.”
