Astronomers think they saw a moon forming around an exoplanet

Scientists have detected a signal around an exoplanet that could be the signature of a circumplanetary disk, a disk of debris that could someday turn into exomoons.

Astronomers have hypothesized that in the early days of Jupiter and Saturn, gigantic planets trapped debris in these circumplanetary disks in orbit. The mass of the disks could then do one of two things: falling on the planet or clumping in the moons. The new results obtained in Chile by Atacama's Large Atacama millimeter / submillimeter network (ALMA) show what could be the proof of one of these discs around a young exoplanet located 370 light years from Earth.

The exoplanet in question calls PDS 70c, the second closest exoplanet to the star parent PDS 70. It orbits away from its young parent star (about 5 million). years), further than the distance between the Sun and Neptune. orbiting slightly closer than a vast ring of dust. Scientists first discovered evidence of the presence of PDS 70c earlier this year using the very large telescope (VLT). The researchers interpreted their results as not only the mark of an exoplanet, but also a surface engulfing part of the gas and dust that surround it.

A team of researchers from the United States, Chile, France, and Germany followed VLT observations by re-analyzing and recalibrating earlier ALMA data on the star system. They were looking for a submillimetric light, a wavelength located between infrared and microwave frequencies of the spectrum, and particularly suitable for the observation of dust clouds. They located a fuzzy sub-millimeter source at the same location as the PDS 70c.

The scientists claim to have located a cloud of dust around the big young planet and deduce that the cloud was a circumplanetary disk. They estimated the mass of the disk between 0.002 and 0.0042 times the mass of the Earth, about a quarter of the mass of our own Moon.

According to an article published in Astrophysical Journal Letters, these dust clouds should theoretically play an important role in the formation of planets. Astronomers believe that the moons of Jupiter and Saturn have formed in a ring like this and that the properties of the ring could determine its properties. Nowadays, astronomers really care about moons, like those that have formed around Jupiter and Saturn, because some of these moons could shelter the conditions of extraterrestrial life.

They also found a mysterious source of submillimeter emissions quite close to PDS 70b, but could not guess with certainty what this show was.

These are always inferences based on fuzzy spots, and there are still many things that astronomers do not understand about planet formation. But if these results withstand further scrutiny, PDS 70c could be a planet in the process of completing its formation phase and could be a good source for understanding how planets – and perhaps even their moons – are formed.