Astronomers have received the first unequivocal observations that the moon formation takes place around an exoplanet in the PDS 70 system, about 370 light years from here, in the constellation Centaur.
In this case, the PDS is not Paulo Maluf’s old party, but it is still from Brazil-sil-sil. It is the acronym for Pico dos Dias Survey, a catalog of young stars identified by the Pico dos Dias Observatory in Itajubá (MG) since 1989.
The PDS 70 system in particular is of great importance. The two well-known planets PDS 70b and c were discovered in 2018 and 2019 through direct observation with the VLT (Very Large Telescope), also in Chile. And last year, an international group used the Hubble Space Telescope to measure the accretion process (growth) of the innermost of them, the PDS 70b. This is why the system is so attractive to astronomers: at around 5 million years old, it is young enough that planet formation is still in progress.
The new observations with the Alma radio telescope set under the direction of Myrian Benisty from the University of Chile now bring an additional element to the interest in the system: the unambiguous detection of a disk of gas and dust around one of the planets, PDS 70c, which represents the Planet formation reproduced on a microscale. The researchers estimate that there is enough mass there to form three Earth-like moons, and the disk itself is huge, comparable to the Earth-Sun distance of 150 million km.
With the result, researchers can study “in real time” how moons form around giant planets, an investigation that should also help explain how the planets themselves are born. In addition, the result confirms that, as expected, the moon-forming process is actually common.
Unlike planet formation, for which there was a single known example for a long time, moon creation was offered to astronomers as a joint process, as all the giant planets in the solar system provide evidence that something like this happened. 4.5 billion years ago. Of course, many of the moons of Jupiter, Saturn, Uranus, and Neptune are just asteroids or gravity-trapped comets, but some of them, larger and arranged in orbits above the planetary equator, suggest local origin from a disk of gas and dust – a miniature version of the birth of planets around the sun.
Still, we have very little evidence of mature exomons. Previous data from satellites used to hunt planets has proven inadequate for them to be discovered with conviction (although there are strong candidates like the bizarre Kepler-1625b, but that’s talking about another day). With the new study accepted for publication in the Astrophysical Journal Letters, the conclusion that remains is that we just need to look better.
This column is published in Folha Corrida on Mondays.
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