They discover a disk around a star in another galaxy

Identificado el origen de las primeras estructuras formadas en galaxias como la Via Lactea

New observations with the Atacama Large Millimeter/submillimeter Array (ALMA), which has the European Southern Observatory (ESO) and other partners in Chile, have made it possible to discover in the Large Magellanic Cloud a young massive star growing, 'accreting' (accumulating). matter from its environment and forming a rotating disk. It is the first time that a disk of this type, identical to those that form planets in our own Milky Way, has been found outside our galaxy.

First observation of a disk around a star in another
Artist's representation of the HH 1177 system in the Large Magellanic Cloud galaxy. The young, massive stellar object shining in the center is taking in matter from a dusty disk while expelling matter through powerful jets. / THAT/M. Kornmesser

“When I first saw evidence of a rotating structure in the ALMA data, I couldn't believe that we had detected the first extragalactic accretion disk. “It was a special moment,” he says. Anna McLeod, associate professor at Durham University (United Kingdom) and lead author of the study published in Nature.

“We know that disks are vital for the formation of stars and planets in our galaxy, and now, for the first time, we are seeing direct evidence of this process in another galaxy,” he emphasizes.


These disks are vital for the formation of stars and planets in our galaxy, and now, for the first time, we see direct evidence of this process in another galaxy

Anna McLeod (Durham University)
This study continues with the observations made with the MUSE instrument, installed on ESO's Very Large Telescope (VLT), which detected a jet launched by a star in formation, a system named HH 1177 inside a gas cloud in the Large Magellanic Cloud.

"We discovered a jet coming from this massive young star, and its presence is a sign of continued accretion of the disk," McLeod said. But to confirm the presence of the disk, the team needed measure the movement of dense gas what's around the star.

Matter attracted to a growing star does not fall directly onto it, but flattens out into a rotating disk around it. The closer it is to the center, the faster the disc spins, and this speed difference It is the irrefutable proof that shows the astronomical community the presence of an accretion disk.

“The frequency of light changes depending on how quickly the gas that emits the light moves closer or farther away from us,” he explains. Jonathan Henshaw, researcher at Liverpool John Moores University (United Kingdom) and co-author of the study. “It is the same phenomenon that occurs when the tone of an ambulance siren changes as it passes and the frequency of the sound goes from high to low,” compares the researcher.

Mother cloud, LHA 120-N 180B (left) captured by MUSE in which the HH 1177 system was observed for the first time. The image in the center shows the jets that accompany it (the part directed towards us is shifted to blue and in red , the distant one). On the right, observed with ALMA. / ESO/SOUL (ESO/NAOJ/NRAO)/A. McLeod et al.

ALMA's detailed frequency measurements allowed the authors to distinguish the characteristic spin of a disk, confirming the detection of the first disk around a young extragalactic star.

The massive stars, like the one observed, form much faster and live much shorter lives than low-mass stars like our Sun. In our galaxy, these massive stars are quite difficult to observe and are often obscured by dusty material from the that are formed when a disk is generated around it.

Thanks to the lower dust content, HH 1177 is no longer wrapped in its original bubble and offers an unobstructed view

However, in the Large Magellanic Cloud, a galaxy 160,000 light years away, the material from which new stars are born is substantially different from that of the Milky Way. Thanks to the lower dust content, HH 1177 is no longer encased in its original bubble, offering astronomers an unobstructed, if distant, view of star and planet formation.

“We are in an era of rapid technological advances when it comes to astronomical facilities,” declares McLeod, excited to “be able to study how stars form at such incredible distances and in a different galaxy.”


Anna F. McLeod et al. “A likely Keplerian disk feeding an optically revealed massive young star.” Nature, 2023

Octavio Alonso