Astronomy Tea Talk
Speaker: Lou Baya Ould Roise (Boston University)
Title: Constraints on Remnant Planetary Systems as a Function of Main-Sequence Mass with HST/COS
Abstract: As the descendants of stars with masses less than 8 solar masses on the main sequence, white dwarfs provide a unique way to constrain planetary occurrence around intermediate-mass stars (spectral types BAF) that are otherwise difficult to measure with radial-velocity or transit surveys. More than 250 ultraviolet spectra of hot, young white dwarfs collected by the Hubble Space Telescope reveal that more than 40% of all white dwarfs show photospheric silicon and sometimes carbon, signpost for the presence of remnant planetary systems. However, the fraction of white dwarfs with photospheric metals significantly decreases for massive white dwarfs (above 0.8 solar mass), descendants of stars with masses greater than 3.5 solar masses on the main sequence, as just 11% exhibit metal pollution.
Since the population of massive white dwarfs is expected to be influenced by the outcome of binary evolution, we investigate merger product signatures among the massive white dwarfs our sample, such as rapid rotation, high magnetism, and fast kinematics. Still, we do not find merger remnants to broadly affect our sample. We connect our measured occurrence rates of metal pollution on massive white dwarfs to empirical constraints into planetary formation and survival around stars with masses greater than 3.5 solar masses on the main sequence.