picture Astronomers have discovered rings of matter that appear to form moons around young exoplanets for the first time and describe their results in a publication released on Thursday.
PDS 70c orbits a star 400 light-years away and is an otherworldly Jupiter-like gas giant of great interest to planetary observers. Unlike most of the other confirmed exoplanets, PDS 70c and its neighbor PDS 70b have not yet fully grown. When they were discovered in 2018 and 2019, respectively, it was even the first time that researchers were able to directly describe a protoplanet.
Recent observations have confirmed that PDS 70c is home to another astronomical gem: surrounded by a cloud of gas and dust where the satellite is slowly starting to form.
“Our work shows a clear recognition of the disk in which satellites can form.” said Myriam Benisty, first author of the article and researcher at the University of Grenoble, France.
Left: ALMA telescope photo of the system around the central star PDS 70. The bright ring is where the planets PDS 70b and PDS 70c formed. Right: Close-up of a bright spot: the moon-forming disk around PDS 70c. Image source: ALMA (ESO / NAOJ / NRAO) / Benisty et al. click to enlarge
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Back 2019, Benisty and his colleagues suspect that they have seen the blurry outline of a circumplanetary disk around the exoplanet. Now they are convinced after seeing it more clearly with the ALMA telescope in the Chilean desert.
“Our ALMA observations were recorded at such excellent resolution that we were able to clearly identify that the disc was connected to the planet and we were able to narrow its size for the first time,” he said.
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The moon-forming disk measures approximately the same distance from our sun to Earth in diameter and has enough mass to form up to three moon-sized satellites. However, it is unclear how many moons will eventually orbit the PDS 70c.
Astronomers believe that satellites form in a similar way to planets. Particles of gas and dust collide and sparkle together to form an accretion disk that continues to grow in size. Evidence of the so-called circumstellar disk where the planets are born has been seen around stars, but the circumplanetary disk where the moons are born is rarely seen.
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“This observation is truly the first in which we have actually been able to demonstrate the existence of a circumplanetary disk — until now we had no definitive evidence for it,” said co-author Richard Teague, associate at the Harvard & Smithsonianian Center for Astrophysics. , said Reg.
“We were also able to measure the size and mass of the disk, which provides clues about its internal structure and the likelihood that this disk will form the moon. Furthermore, because we have tremendous data on circumstellar disks, we can put all these limitations in the context of larger circumstellar disks to understand whether their environment is similar to what the theory predicts that they will most likely form circumplanetary disks.”
The researchers believe that the two exoplanets, PDS 70c and PDS 70b, provide a favorable environment for studying the conditions necessary for the formation of the moon.
“One of the great puzzles in this system is the difference between the two planets. Both planets were found in the near infrared, but only PDS 70c appears to have a clear planetary disk. We want to better understand the differences between these two planets,” added Teague.
“For example, PDS 70c starved to death, PDS 70b? Can all circumstellar disc material be collected before the PDS 70b has a chance? However, having the opportunity to study an example of a moon-forming disc is good [the planetary system] unique in that it allows us to examine the two and the interactions between them. ”®
