Measuring the mass and time available to form planets

University Of Arizona, Tucson AZ

Investigators

Abstract

Planets are ubiquitous in our Galaxy, in systems often different from our own Solar System and far more diverse than originally predicted by theoretical models. What is the origin of this diversity? Current data suggest that part of this diversity arises from the properties of circumstellar disks around young stars, the birth sites of planets. As part of this NSF investigation the team will measure two fundamental properties of circumstellar disks by analyzing two unique datasets, one of which comes from the Atacama Large Millimeter Array, an international facility supported by NSF. This investigation goes beyond the state-of-the-art both in the achieved sensitivity and in the methods the team will apply to homogeneously compute stellar and disk properties. While addressing key questions identified in the United States' 2010 Astronomy and Planetary Science Decadal surveys, the work will advance education and training by involving both graduate and undergraduate students in the proposed activities. The team will further contribute to increasing access for currently underrepresented groups to STEM education by developing a K-12 teacher workshop that will reach out to Hispanic and Native American communities. The masses of circumstellar disks and the rate at which disk material is accreted onto the central star are the two most fundamental parameters of disk evolution and planet formation models. As part of this investigation we will establish the scaling laws between these two quantities and the mass of the central star. To do that we will analyze a unique dataset obtained with the Atacama Large Millimeter Array (ALMA) and measure disk masses and their intrinsic spread over a range of 40 in stellar mass. The team will also analyze sensitive medium-resolution optical spectra for each of the ALMA targets and employ newly developed techniques to determine accurate stellar masses and accretion rates. The results will provide critical inputs to theoretical models of planet formation and help understanding the diversity of exoplanetary systems. Along with advancing research, the team will train students and develop a K-12 teacher workshop and hand-on activities to investigate habitability and methods for planet detection that teachers can use in the classroom.