The Mass Budget of Planet Forming Discs: Isolating the Epoch of Planetesimal Formation

TL;DR

This paper uses planet detection data and disc observations to constrain the timing and efficiency of planet formation, indicating it begins within a few million years and involves significant solid mass conversion.

Contribution

It provides new constraints on the planet formation epoch and efficiency by comparing planet statistics with protoplanetary disc solid inventories.

Findings

Planet formation likely begins within a few million years.

A large fraction of solids are converted into large objects or sequestered.

Planet formation occurs early in the disc evolution process.

Abstract

The high rate of planet detection among solar-type stars argues that planet formation is common. It is also generally assumed that planets form in protoplanetary discs like those observed in nearby star forming regions. On what timescale does the transformation from discs to planets occur? Here we show that current inventories of planets and protoplanetary discs are sensitive enough to place basic constraints on the timescale and efficiency of the planet formation process. A comparison of planet detection statistics and the measured solid reservoirs in T Tauri discs suggests that planet formation is likely already underway at the few Myr age of the discs in Taurus-Auriga, with a large fraction of solids having been converted into large objects with low millimeter opacity and/or sequestered at small disc radii where they are difficult to detect at millimeter wavelengths.