Collaborative Research: The Evolution of Gas in Protoplanetary Disks

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The objective of the proposed work is to build understanding of the behavior and evolution of gas in protoplanetary disks. Up to 99% of the mass of a protoplanetary disk consists of gas. However, astronomers do not have even a basic understanding of the evolution of the gas component or what factors drive such evolution. Observations of protoplanetary disks, collected with the ALMA radio observatory, will be used to test the two leading theories of disk evolution. The UW-Madison group will design and provide a regular 1-hour long hands-on session on the topic of radio waves for student group visitors at the UW-Madison Space Place, a local outreach and educational center. In Tucson, AZ, the UA group will develop a one day workshop for K-12 teachers on the topic of radio waves, by collaborating with the Pima County School Superintendent's Office. In addition, this work will provide research experience to graduate students, undergraduates, and a post-doc.This project will provide a legacy library of robust measurements of gas disk masses and sizes in a well-defined sample spanning over the whole disk lifetime (0.1-10 Myr). Such library will be critical to test any current and future theories of disk evolution. This project will gather breakthrough data to map the evolution of gas in protoplanetary disks, through the ALMA survey of Gas Evolution in PROtoplanetary disk, AGE-PRO, an accepted ALMA Cycle 8 large program (103 h, PI. Zhang). They will collect and analyze deep ALMA observations of a comprehensive sample of disks throughout the typical disk lifetime. By combining AGE-PRO observations and state-of- the-art thermo-chemical models, the team will provide accurate gas mass measurements of these disks (10-20 times better accuracy than existing constraints), as well as detailed surface density distributions of gas in these disks. They will then run a large grid of disk evolution models under different disk evolution mechanisms. Comparing their gas distribution measurements from observations with that of disk evolution models, they will provide critical tests to the two leading theories of disk evolution: turbulent viscosity and magneto-hydrodynamical disk winds.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.