Early Signs of Structure in Protostellar Disks

Abstract

Protostellar disks—rotating disks of gas and dust around pre-fusion ignition young stars—are divided into four main classes: Class 0: the youngest class, still deeply embedded in their parent molecular clouds and accumulating mass, with a lifespan on the order of 100k years. Class I: still embedded in molecular clouds, characterized by strong infrared and radio emissions generated by the heat from the collapsing central protostar, with a typical lifespan of a few hundred thousand years. Class II: more evolved with decreased accretion rates and active planet formation. Lifespan on the order of 2-3 million years. Class III: low accretion rate debris (mostly dust) disks. Remnants of planetary formation process. Typical lifespan of several million years. Focusing on the youngest disks, Classes 0 and I, we are investigating how early structure begins to show in the form of gaps and rings, indicating potential future planet formation. We use high resolution and high sensitivity (sub)millimeter wavelength observations from the ALMA (Atacama Large Millimeter/submillimeter Array) interferometer. Having identified approximately 10,700 potential Class 0 or I disks in the ALMA archive, we make use of several specialized code packages designed to fit or examine individual disks from their frequency space visibility data rather than from images to build a step-by-step process taking the initial ALMA data and providing the decision-making ability to categorize the disks into four primary categories: Smooth, Structured, Further Investigation, Not Usable. Having used the summer term to build, streamline, and document the needed process, we report building an initial catalog of usable Class 0 and Class I sources that contains 36 individual objects, with 7 categorized as Smooth, 8 as having Structure, and 6 needing Further Investigation.