Astronomers spot a young star forming in a similar way to how planets are born

The observations were made using the Atacama Array in the Chilean desert

A group of astronomers led by Dr John Ilee from the University of Leeds has spotted a young star forming like a planet.

Astronomers were observing a young massive star, known as MM 1a, and the rotating disc of gas and dust around MM 1a when they found a faint, baby star, MM 1b, orbiting MM 1a.

The finding was made using Atacama Large Millimetre/submillimetre Array (ALMA) situated in the Chilean desert. Astronomers used interferometry process to combine the power of 66 separate dishes of ALMA. In this way, they were able to observe the material surrounding both stars for the first time.

In an uncommon observation, researchers found that the rotating disc around MM 1a was "fragmented" and MM 1b was located beyond this disc.

Stars are formed within the large clouds of dust and gas in interstellar space. When these large clouds collapse under gravity, they start rotating faster, eventually creating a disc around them.

"In low mass stars like our Sun, it is in these discs that planets can form. In this case, the star and disc we have observed is so massive that, rather than witnessing a planet forming in the disc, we are seeing another star being born," said Dr Ilee, from the School of Physics and Astronomy at Leeds.

The team also calculated the mass of both stars and found that the mass of MM 1b is less than half the mass of our Sun. In contrast, the mass of MM 1a is about 40 times the mass of our Sun, meaning the binary star system has a mass ratio of 80:1.

Dr. Ilee reveals that many older massive stars with a companion star have been discovered in the past. However, those stars were found to have almost the same mass as their companion star, suggesting that both stars probably came into being together as siblings.

"Finding a young binary system with a mass ratio of 80:1 is very unusual, and suggests an entirely different formation process for both objects," Dr. Ilee added.

The team thinks MM 1b could also be surrounded by its own circumstellar disc with potential to create planets of its own.

The findings of the study are published in the Astrophysical Journal Letters.