The disk and jet in the young star system HH 1177 seen with MUSE and ALMA.
Accretion disks play an essential role in the formation of stars and planets in the Milky Way. For example, Earth and the planets of our solar system were born from rocks and dust that orbited the Sun.
When I first saw evidence of a rotating structure in the ALMA data, I couldn't believe we had detected the first extragalactic accretion disk. It was an extraordinary moment, said astrophysicist Anna McLeod, professor at the University of Durham and lead author of the article published in the journal Nature. New window) (in English).
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Artistic illustration showing a nascent star surrounded by a disk in which planets are form.
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In 2019, the MUSE instrument installed on the Very Large Telescope of the European Southern Observatory also installed in Chile made it possible to detect a region of the Large Magellanic Cloud populated by newly formed stars.
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Color composite image of the Large Magellanic Cloud region populated by newly formed stars.
At the time, MUSE also detected a jet from a massive nascent star with a mass 12 times that of the Sun. This jet, which spans nearly 33 light years, has been named HH 1177. It is not only the first of its type observed in visible light outside the Milky Way, but also one of the longest jets observed to date.
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The present work was carried out following that carried out in 2019. Their authors wanted to check whether the jet was associated with the presence of an accretion disk. To establish this, scientists had to measure the movement of dense gas around the star.
The frequency of the Light changes depending on the speed at which the light-emitting gas moves closer or further away from us, says British astrophysicist Jonathan Henshaw, of Liverpool John Moores University and co-author of the study.
This is exactly the same phenomenon that occurs when the tone of a Ambulance siren changes as it passes you and the frequency of the sound goes from a higher level to a lower level.
A quote from Jonathan Henshaw, John's University Moores
Thanks to detailed frequency measurements carried out by ALMA, researchers were able to distinguish the characteristic rotation of a disk confirming the detection of the first disk around a young extragalactic star.
To be categorized as massive, a star must have a mass that exceeds that of the Sun by approximately eight times. These stars form much more quickly and live much shorter than low-mass stars like our Sun, note the researchers.
Their observation is often made difficult since they are bathed in the dusty material from which they develop, but also from which the disks which give birth to the planets are formed.
In the case of the Large Magellanic Cloud, the material from which new stars are born is fundamentally different from that of the Milky Way. Thanks to its low dust content, HH 1177 is no longer enveloped in its native cocoon, providing astronomers with a clear, albeit distant, view of star and planet formation.
A quote from Authors in a press release
Being able to study star formation at such incredible distances and in a different galaxy is very exciting, says Anna McLeod.