Astronomers discover disc around young star in neighbouring galaxy

Astronomers, using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, have discovered a disc around a massive young star in the Large Magellanic Cloud, a neighbouring galaxy of ours.

The discovery marks the first time such a disc, identical to those forming planets in our own galaxy, has ever been found outside our Milk Way.

This study follows up observations with the Multi Unit Spectroscopic Explorer (MUSE), an instrument aboard the European Southern Observatory's Very Large Telescope (VLT), which spotted a jet from a forming star deep inside a gas cloud in the LMC. The system was named HH 1177.

To confirm the disc's presence, the team needed to measure the movement of the dense gas around the star.

As matter is drawn toward a growing star, it doesn't directly descend onto the star but rather forms a rotating disk around it. The inner regions of the disk exhibit a higher rotational speed, and this discrepancy serves as compelling evidence for astronomers, indicating the presence of an accretion disk. Utilizing precise frequency measurements from ALMA, the researchers were able to discern the distinct rotation pattern of the disk, confirming the detection of the first disc around an extragalactic young star.

"We discovered a jet being launched from this young massive star, and its presence is a signpost for ongoing disc accretion," said Anna McLeod, an associate professor at Durham University in the UK and lead author of the study published today in Nature.

According to the researchers, stars like the one studied here form much more quickly and live far shorter lives than low-mass stars like our Sun. These massive stars in our galaxy are notoriously challenging to observe and are often obscured from view by the dusty material from which they form at the time a disc is shaping around them.

Notably, in the case of LMC, the material from which new stars are being born is fundamentally different from that in our galaxy. HH 1177 is no longer cloaked in its natal cocoon because of lower dust content. This offers astronomers an unobstructed, if far away, view of star and planet formation.

1/ 📣 Using @almaobs , in which ESO is a partner, astronomers have discovered a disc around a star in another galaxy for the first time — a remarkable find, as these discs are the birthplace of new stars and planets! ✨🪐More info: https://t.co/BhuLdxrDhn pic.twitter.com/zV31kqa4OW

— ESO (@ESO) November 29, 2023