Alan

Boss

Solar System & Exoplanets

Alan Boss' theoretical research includes the formation of binary and multiple stars, triggered collapse of the presolar cloud, mixing and transport processes in protoplanetary disks, including thermal processing of particles during their journeys, and the formation of gas giant and ice giant protoplanets. His observational works centers on the Carnegie Astrometric Planet Search project, which has been underway for the last decade at Carnegie's Las Campanas Observatory in Chile.

Overview

Alan Boss is a theorist and an observational astronomer. His theoretical work focuses on the formation of binary and multiple stars, triggered collapse of the presolar cloud that eventually made the Solar System, mixing and transport processes in protoplanetary disks, and the formation of gas giant and ice giant protoplanets. His observational works centers on the Carnegie Astrometric Planet Search project, which has been underway for the last decade at Carnegie's Las Campanas Observatory in Chile.

While fragmentation is universally recognized as the dominant formation mechanism for binary and multiple stars, there are still major questions. The most important of these is the role of magnetic fields. Boss has been studying the collapse of individual molecular cloud cores via special computer modeling, to understand the chances for binary and multiple star system formation and to define which cloud cores are likely to collapse to form single stars, such as our Sun.

A shock from an exploding star called a supernova has been considered the most attractive mechanism for introducing short-lived radioisotopes (SLRIs) into the solar nebula. Boss has been modeling the problem of simultaneous triggering and injection. His results support the supernova trigger hypothesis because thin supernova shocks are better at injecting SLRIs than the thick planetary nebula. Boss is currently running 3D models, including the effects of target cloud rotation, to learn to what extent injection occurs into a protoplanetary disk formed as a result of triggered collapse.

Boss also studies the mixing and transport of solids in protoplanetary disks to form gas giant planets similar to Jupiter, or to undergo outbursts in marginally gravitationally unstable (MGU) disks. Boss' 3D models show how crystalline silicates, observed in the outskirts of protoplanetary disks and in long-period comets, could have been formed by thermal “cooking” closer to their protostar and then transported back outward to cooler regions of the disk. Boss has joined with Conel Alexander and Morris Podolak to study the detailed thermal evolution of finite-size particles in MGU disks.

While the core accretion mechanism is still considered by most to be the leading explanation for the formation of our solar system's gas giant planets, for the last decade Boss has been working to learn whether another mechanism, disk instability, could also form gas giant planets.

Along with Alycia Weinberger and Ian Thompson, Boss has been running the Carnegie Astrometric Planet Search (CAPS) program, which searches for extrasolar planets by the astrometric method, where the planet's presence is detected indirectly through the wobble of the host star around the center of mass of the system. With over six years of CAPSCam data, they are beginning to see likely true astrometric wobbles..

Boss received his B.S. from the University of South Florida and his M.A. and Ph. D. in physics from UC-Santa Barbara, where he was also a postdoctoral researcher. Before joining Carnegie in 1981 as a staff associate (now a staff scientist), he was a research associate at NASA Ames Research Center.