Artist's impression of seven Earth-sized rocky exoplanets orbiting the ultracool dwarf star TRAPPIST-1. The system is located about 40 light-years away in the constellation of Aquarius. The planets may be rich in volatile materials, likely water, raising the possibility that some of them could support life. Credits: Eso.org
Gabriele Pichierri
Abstract
ALMA line surveys offer a unique opportunity to study large populations of protoplanetary disks with low integration times per source.
Resonant multi-planet systems occupy a privileged role at the interface of observation and theory of exoplanetary science. Observationally, they produce coherent variations that allow precise mass and orbital constraints.
Theoretically, they pose a puzzle: while models readily produce compact resonant chains, many appear fragile to instabilities and they are relatively rare in the exoplanet sample.
Thus, the few remaining resonant chains are the ones that encode a system’s history and act as fossils of their assembly environment.
TRAPPIST-1, a ~7 Gyr-old red dwarf, is a particularly exciting example.
It hosts a 7-planet resonant chain, the longest known so far, with period ratios of neighbouring pairs close to 8:5, 5:3, 3:2, 3:2, 4:3, and 3:2 in increasing distance from the star.
This remarkable configuration can unveil key physical processes that were likely active in the protoplanetary disc.