Protoplanetary Disks around Pre-main Sequence Binary Stars

Knowledge gained from studying stellar binaries is often widely applicable to understanding broad swaths of astrophysics. The dynamics of these systems enable direct measurements of stellar mass, the fundamental parameter governing stellar evolution and subsequent death. In particular, pre-Main Sequence binaries hosting circumbinary disks provide a unique means to access fundamental astrophysical properties during the epoch of planet formation. First, we show how ALMA observations of these systems have validated the accuracy of the disk-based dynamical mass technique, whereby the disk velocity field is reconstructed to deliver precise (< 5%) constraints on stellar mass, and opened the technique for application to a vast sample of single star systems. Such a sample of precise stellar masses is a prerequisite for calibrating theoretical models of pre-Main Sequence evolution, and we have taken initial steps towards this a goal with a moderately-sized sample of dynamical masses from the Submillimeter Array. Second, circumbinary protoplanetary disks provide an excellent opportunity to link observables like stellar mass and orbital inclination to properties of the disk to study effects like pulsed accretion and stellar-disk mutual inclination. From the Kepler mission, we know circumbinary planets form readily, but many questions remain about their formation mechanisms and mutual inclinations. Lastly, to fully realize the potential of these systems requires detailed, time-series spectroscopy at optical and infrared wavelengths to refine orbital solutions and learn about fundamental stellar properties like effective temperature and composition. To conclude, we present a novel technique that uses Gaussian processes to disentangle the spectra of binary stars, and discuss its potential applications for studying variability in young stars.

Ian Czekala
KIPAC Postdoctoral Fellow at Stanford University
Speaker Introduction: 

Ian Czekala received his PhD from Harvard and is currently a KIPAC Postdoctoral Fellow at Stanford University, working on protoplanetary disks, pre-main sequence evolution, and exoplanets, and is also at the forefront of statistical/coding techniques.

KIAA-PKU Auditorium
Gregory Herczeg
Thursday, May 25, 2017 - 4:00pm to 5:00pm