Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have detected a rotating gaseous structure around an extragalactic massive young stellar object in the star-forming region N180, which is part of the Large Magellanic Cloud, a neighboring dwarf galaxy, 163,000 light-years away. They’ve observed motions in gas around the star consistent with a so-called Keplerian accretion disk — the kind that feeds the growth of stars through infalling material. This is the most distant disk around a massive star ever to be directly detected.
“The Large Magellanic Cloud is a convenient environment for searching for the extragalactic counterparts of the accreting massive young stellar objects known in the Milky Way,” said Durham University astronomer Anna McLeod and her colleagues.
“For example, there is the recent detection of molecular outflows, as well as the discovery of Herbig-Haro object 1177 (HH 1177), a collimated bipolar jet driven by a massive young stellar object.”
“Although the detection of a molecular outflow from a forming star does not necessarily imply the presence of an accretion disk, collimated jets are generally taken as clear signposts for ongoing disk accretion.”
“To date, there has been no direct detection of a rotating circumstellar Keplerian disk or toroid in an external galaxy, making the HH 1177 star/jet system an ideal target to search for these.”
“ALMA now enables the high-sensitivity and high-angular-resolution observations needed to detect and resolve rotating circumstellar gas in extragalactic massive young stellar objects.”
The rotating disk detected by ALMA is feeding the central star of the HH 1177 system.
“When I first saw evidence for a rotating structure in the ALMA data, I could not believe that we had detected the first extragalactic accretion disk; it was a special moment,” Dr. McLeod said.
“We know disks are vital to forming stars and planets in our Galaxy, and here, for the first…
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