Phoenix Giants: their connection to the fate of short-orbital period binary stars and their potential for rebirthing planetary systems

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Dr. Carl Melis is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the University of California, San Diego (UCSD). Multiple stellar systems are ubiquitous in our Galaxy and likely in other galaxies as well. Understanding how these systems evolve over time, especially when individual components begin the giant phase of stellar evolution, are critical in determining the final states of these groups of stars and how they will affect the evolution of their host galaxies. Dr. Melis will characterize a new class of first-ascent giant stars discovered in the PI's thesis research and will connect them to the final stages of multiple-star evolution for a special class of short orbital-period binary systems. Dubbed "Phoenix Giants," these first-ascent giant stars are nearing the end of their lives, yet are surrounded by dusty and gaseous disks similar to those found around young, planet forming stars. The research program will include a comprehensive observational campaign extending from the near-infrared to the microwave, model fitting of these data sets to derive the structures of Phoenix Giant disks, and the development of analytical and numerical models describing the interaction between tightly bound pairs when the primary enters into the first-ascent giant phase of evolution. Comparison of the observational results for Phoenix Giant disk structure to the analytical and numerical modeling results will aid in connecting the Phoenix Giant phenomenon and the fate of short orbital-period binaries. The data obtained will also be extended to probe whether Phoenix Giant disks are hospitable environments for forming protoplanets and hence to begin to answer the question of whether these stars can undergo a second epoch of planet formation billions of years after their first.Dr. Melis will also conduct a program of education and outreach aimed at the recruitment, retention, and advancement of students in science, technology, engineering, and mathematics (STEM). Dr. Melis will develop and teach a laboratory course for UCSD advanced undergraduate physics and engineering majors that will incorporate best practices from recent educational research and lessons learned from astronomy laboratory courses successfully implemented at other institutions. This laboratory course will focus on preparing students for advanced academic studies or industry work within STEM through the development of relevant technical skills, but will also introduce students to the basics of observational astronomy research. Dr. Melis will also volunteer with Project ASTRO to bring astronomy to the earliest levels of pre collegiate education where young minds can be turned on to science. These two educational programs will plant the seeds of a science career in young students' minds and provide them the tools in a collegiate setting to succeed in a STEM career path.