ALMA Observes Birth Cry of a Massive Baby Star

[bystander]

ALMA Observes Birth Cry of a Massive Baby Star
ALMA | ESO | NRAO | NAOJ | 2017 Jun 12

[c][imghover=https://alma-telescope.jp/assets/upload ... 1706-a.png]https://alma-telescope.jp/assets/upload ... 706-rb.png[/imghover]Orion KL Source I imaged with ALMA -- In image 1, the massive protostar is in
the center and surrounded by a gas disk (red). A bipolar gas outflow is ejected
from the protostar (blue). Image 2 shows the rotation of the outflow of gas; red
shows gas moving away from us, whereas blue shows gas moving toward us.
Credit: ALMA (ESO/NAOJ/NRAO), Hirota et al[hr][/hr][/c]

An international research team used the Atacama Large Millimeter/submillimeter Array (ALMA) to determine how the enigmatic gas flow from a massive baby star is launched. The astronomers observed the baby star and obtained clear evidence of rotation in the outflow. The motion and the shape of the outflow indicate that the interplay of centrifugal and magnetic forces in a disk surrounding the star plays a crucial role in the star’s birth cry.

Stars form from gas and dust floating in interstellar space. But, astronomers do not yet fully understand how it is possible to form the massive stars seen in space. One key issue is gas rotation. The parent cloud rotates slowly in the initial stage and the rotation becomes faster as the cloud shrinks due to self-gravity. Stars formed in such a process should have very rapid rotation, but this is not the case. The stars observed in the Universe rotate more slowly.

How is the rotational momentum dissipated? One possible scenario involves that the gas emanating from baby stars. If the gas outflow rotates, it can carry rotational momentum away from the system. Astronomers have tried to detect the rotation of the outflow to test this scenario and understand its launching mechanism. In a few cases signatures of rotation have been found, but it has been difficult to resolve clearly, especially around massive baby stars. ...

Disk-Driven Rotating Bipolar Outflow in Orion Source I - Tomoya Hirota et al

• Nature Astronomy 1:0146 (12 Jun 2017) DOI: 10.1038/s41550-017-0146