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Jan 17 2019

ALMA photographed an unusual star duo

A team of researchers from the University of Leeds reported an unusual discovery made with the help of the ALMA (Atacama Large Millimeter / submillimeter Array) radio telescope complex. It was made in the process of studying the emerging star MM 1a, located at a distance of 11 thousand light years from the sun. 


System MM 1 as an artist 

MM 1a is still surrounded by a gas and dust disk. During the observations, the ALMA system detected an object whose orbit runs around a star. This is another light. It received the designation MM 1b. At first glance, there is nothing extraordinary in the discovery, because about half of the Milky Way stars are part of multiple systems. However, MM 1b has one interesting feature that made astronomers take a closer look at it. It’s all about the mass ratio between the stars. 

Image of the MM 1 system obtained by ALMA. Red color corresponds to the receding (from the point of view of the earth observer) gas, blue – to the approaching gas. 

As a rule, stars in binary systems have a similar mass due to the fact that they formed under the same conditions. However, MM 1 is an exception to this rule. After studying the data ALMA, the researchers concluded that the mass of the main component of the system is about 40 solar. The mass of the second star is 80 times less. It ‘weighs’ like half of our sun. 

Stars are formed during the gravitational collapse of gas and dust clouds. As it compresses, the gas heats up and the cloud becomes a protostar, transforming into a rotating spherical object surrounded by a disc of the remaining substance. Low-mass stars such as our Sun may have planets in these disks. However, in this case, the star and its surroundings were so massive that instead of a planet, another star was formed in it.

Image of the MM 1 system obtained by ALMA. Green color corresponds to dust, red and blue – gas. 

According to the researchers, MM 1b can also be surrounded by its own gas and dust disk in which planets can form. True, most likely, they will have very little time. By astronomical standards, such MM 1a giant stars do not live long – no more than a couple of million years. After that, they end their lives in dazzling flashes of supernovae.





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