Preliminary Evidence That Protoplanetary Disks Eject More Mass Than They Retain

TL;DR

This study suggests that protoplanetary disks eject significantly more mass than they retain, based on interstellar object observations, challenging existing models of planetary system formation.

Contribution

It introduces the concept of Minimum Ejection Fraction (MEF) and provides the first empirical constraint on the mass ejected by protoplanetary disks from interstellar object data.

Findings

At least 10% of stellar mass is ejected into interstellar space.

The MEF is estimated to be between 2% and 50%.

More mass is processed per star than in the MMSN model.

Abstract

If interstellar objects originate in protoplanetary disks, they can be used to calibrate the fraction of mass that such disks eject. The discoveries of interstellar objects 1I/`Oumuamua and 2I/Borisov, taken together with rogue planets statistics, allow for the calibration of mass locked in interstellar objects in size range $\sim 10^{4} - 10^{9} \; \mathrm{cm}$. Here, we show that at least $\sim 10\%$ of stellar mass is required to produce the observed population of interstellar objects, with a 95\% confidence interval spanning $\sim 2\% - 50\%$. We call this quantity the Minimum Ejection Fraction (MEF), representing a new constraint on planetary system formation that necessitates an order of magnitude more mass to be processed per star than in the Minimum Mass Solar Nebula (MMSN) model. Future discoveries of interstellar objects with LSST on the Vera C. Rubin Observatory will provide a test of our predictions and improve the statistics.