Exploring the Relationship Between Stellar Mass and Planet Occurrence

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Dr. John Johnson is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the Institute for Astronomy at the University of Hawaii. Over 150 nearby stars are known to harbor planetary companions, and the physical properties of these host stars provide an important link between the planets detected today and the circumstellar environments from which they formed. Determining the relationship between stellar mass and planet occurrence provides an important test of the core accretion model of planet formation, which predicts how the fraction of stars with planets increases with stellar mass. To measure the occurrence rate of planets as a function of mass, the PI will conduct a precision Doppler survey of intermediate-mass subgiants at Keck Observatory. Subgiants are ideal planet-search candidates due to their narrower spectral lines and lower atmospheric noise compared to their early-type progenitors. This search probes a unique stellar parameter space and will double the mass range of current Keck Doppler surveys.Dr. Johnson will also implement a program of educational outreach in elementary schools using hands-on and multimedia activities that merge planetary science and state-mandated science standards. The lesson plans will be taught in collaboration with Honolulu-area 4th- and 5th-grade teachers. The activities are designed to take students on a journey that begins at the Sun, progresses through the planets of our Solar System, and culminates with the exotic worlds recently discovered around other stars. By serving as a minority role model, Dr. Johnson is uniquely positioned to encourage young, underrepresented students to pursue careers in astronomy.