Astronomers have discovered the first example of a swirling disk of material feeding a young star in a galaxy beyond the Milky Way. The disks are nearly identical to those found around infant stars in the Milky Way, suggesting that stars and planets form in other galaxies just as they do in our galaxy. Masu.
The young star in question is located in the Large Magellanic Cloud (a neighboring galaxy to the Milky Way 160,000 light-years away), and its system, called HH 1177, is embedded in a giant gas cloud.
The team behind the discovery used the Atacama Large Millimeter/Submillimeter Array (ALMA), the largest astronomical project on Earth, consisting of 66 antennas in northern Chile that make up a single radio telescope. I observed this lever system.
“When we first saw evidence of rotating structures in the ALMA data, we couldn’t believe we had detected the first extragalactic accretion disk. It was a special moment,” said study lead author Anna, a scientist at Durham University.・Mr. McLeod stated. said in a statement. “We know that disks are essential for forming stars and planets in our galaxy, but here, for the first time, we see direct evidence of this in another galaxy.”
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McLeod and colleagues were alerted to the system’s existence when the Multi-Unit Spectroscopic Explorer (MUSE) instrument aboard ESO’s Very Large Telescope (VLT) spotted jets emerging from forming stars. . While observing in the visible wavelength range, the instrument can also measure the wavelength of light emitted by objects, allowing scientists to know what type of material they are observing.
“We discovered jets being launched from this young, massive star, and their presence is a signpost to ongoing disk accretion,” McLeod added. To confirm the presence of an accretion disk in HH 1177, scientists needed to measure the movement of dense gas around the star.
Accretion disks inside and outside the Milky Way galaxy
Accretion disks, like this newly observed one, form when material falls toward an infant star or another accreting object, such as a black hole or neutron star. When matter falls onto these objects, it gains angular momentum (rotational spin). This means that matter cannot directly reach its central object. Instead, this material forms a flat rotating disk that gradually feeds material into the central object.
Gas at the center of the accretion disk, closer to the central object (in this case a young feeding star), moves faster than material outside the disk, and this change in velocity is the “smoking gun”. It indicates the existence of an accretion disk.
“The frequency of the light changes depending on how fast the light-emitting gas moves toward or away from us,” said team member Jonathan Henshaw, a researcher at Liverpool John Moores University. “This is exactly the same phenomenon that occurs when an ambulance siren changes pitch as it passes, changing the frequency of the sound from higher to lower.” is known as redshift or blueshift, depending on whether it is moving toward or away from Earth.)
Astronomers have previously discovered bright accretion disks around objects such as supermassive black holes in other galaxies. This is because their massive gravity creates violent conditions, and the gas and dust within these disks shine brightly, often outweighing the combined light of all the stars in the surrounding galaxies. is. . But the accretion disks around stars where planets eventually emerge are much harder to find, even within the Milky Way. Part of the reason is that young stars are often still trapped within the gas and dust clouds from which they were born.
In the Large Magellanic Cloud, the situation is somewhat different because the material producing young stars does not contain much dust. This means HH 1177 has already escaped most of its natal “cocoon”, allowing astronomers to observe its central star and perhaps even observe the early stages of planet formation. . Our own solar system would have gone through the same process about 4.5 billion years ago, when a protoplanetary disk surrounded the young Sun during the birth of planets.
“We are in an era of rapid technological advancement when it comes to astronomical facilities,” McLeod said. “It’s very exciting to be able to study how stars form in another galaxy so far away.”
The team’s research has been published in a paper published in the journal Nature Wednesday, November 29th.