Chalmers: ALMA Witnesses the Birth of a Massive Binary Star

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Chalmers: ALMA Witnesses the Birth of a Massive Binary Star

Post by bystander » Tue Mar 19, 2019 6:01 pm

Spiraling Giants: ALMA Witnesses the Birth of a Massive Binary Star
Chalmers University of Technology | ALMA | 2019 Mar 18
A team of astronomers ... have made new observations with ALMA of a molecular cloud that is collapsing to form two massive protostars that will eventually become a binary star system.

​While it is known that most massive stars possess orbiting stellar companions it has been unclear how this comes about. Are the stars born together from a common, spiralling gas disk at the center of a collapsing cloud, or do they pair up later by chance encounters in a crowded star cluster?

Understanding the dynamics of forming binaries has been difficult because the protostars in these systems are still enveloped in a thick cloud of gas and dust that prevents most light from escaping. Fortunately, it is possible to see them using radio waves, as long as they can be imaged with sufficiently high spatial resolution. ...

The observations showed that already at this early stage, the cloud contains two objects, a massive “primary” central star and another “secondary” forming star, also of high mass. For the first time, the research team were able to use these observations to deduce the dynamics of the system. The observations showed that the two forming stars are quite far apart, separated by a distance of about 180 astronomical units (180 times the distance from the Earth to the Sun). They are currently orbiting each other with a period of at most 600 years, and have a total mass at least 18 times that of our Sun. ...

ALMA Shows Birth of Spiraling Giants
National Radio Astronomy Observatory | 2019 Mar 18

Dynamics of a Massive Binary at Birth ~ Yichen Zhang et al
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