Predicting the Kinematic Evidence of Gravitational Instability

• Published in: The Astrophysical journal Vol. 904; no. 2; pp. 148 - 155
• Main Authors: Hall, C., Dong, R., Teague, R., Terry, J., Pinte, C., Paneque-Carreño, T., Veronesi, B., Alexander, R. D., Lodato, G.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01-12-2020; IOP Publishing; American Astronomical Society
• Subjects: Accretion disks; Astrophysics; Extrasolar planets; Fluid dynamics; Fluid flow; Gravitation; Gravitational instability; Hydrodynamics; Instability; Kinematics; Mass budget; Planet formation; Protoplanetary disks; Radiative transfer; Radiative transfer calculations; Radio telescopes; Sciences of the Universe; Signatures; Spirals; Astrophysics - Astrophysics of Galaxies; Protoplanetary disks; 1300; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/abac17

Observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) have dramatically improved our understanding of the site of exoplanet formation: protoplanetary disks. However, many basic properties of these disks are not well understood. The most fundamental of these is the total disk mass, which sets the mass budget for planet formation. Disks with sufficiently high masses can excite gravitational instability and drive spiral arms that are detectable with ALMA. Although spirals have been detected in ALMA observations of the dust, their association with gravitational instability, and high disk masses, is far from clear. Here we report a prediction for kinematic evidence of gravitational instability. Using hydrodynamics simulations coupled with radiative transfer calculations, we show that a disk undergoing such instability has clear kinematic signatures in molecular line observations across the entire disk azimuth and radius, which are independent of viewing angle. If these signatures are detected, it will provide the clearest evidence for the occurrence of gravitational instability in planet-forming disks, and provide a crucial way to measure disk masses.