Constraining protoplanetary disc mass using the GI wiggle

TL;DR

This paper demonstrates that the amplitude of the gravitational instability (GI) wiggle in protoplanetary discs, observable with ALMA, can be used to estimate the disc-to-star mass ratio, aiding in measuring disc mass.

Contribution

The study empirically establishes a linear relationship between GI wiggle amplitude and disc-to-star mass ratio using simulations, enabling mass estimation from observations.

Findings

GI wiggle amplitude correlates linearly with disc-to-star mass ratio

ALMA can measure GI wiggle amplitude accurately

Disc mass constraints improve understanding of planet formation processes

Abstract

Exoplanets form in protoplanetary accretion discs. The total protoplanetary disc mass is the most fundamental parameter, since it sets the mass budget for planet formation. Although observations with the Atacama Large Millimeter/Submillimeter array (ALMA) have dramatically increased our understanding of these discs, total protoplanetary disc mass remains difficult to measure. If a disc is sufficiency massive ($\gtrsim$ 10\% of the host star mass), it can excite gravitational instability (GI). Recently, it has been revealed that GI leaves kinematic imprints of its presence known as the "GI Wiggle." In this work, we use numerical simulations to empirically determine an approximately linear relationship between the amplitude of the wiggle and the host disc-to-star mass ratio, and show that measurements of the amplitude are possible with the spatial and spectral capabilities of ALMA. These measurements can therefore be used to constrain disc-to-star mass ratio.