Host star abundances provide a glimpse into the elements (and their abundances) that were available for planet formation around them, which serves as a baseline for comparison with the planetary abundances.. Past work has found relationships between planet occurrence and the abundance of individual elements such as Mg, Si, and Ni for the transiting planets discovered by Kepler. However, no such study has been conducted among the directly imaged planet population. Measuring the detailed chemical makeup of the host star (in addition to carbon and oxygen) could allow us to investigate some of these population trends among this population of companions. My past work (Baburaj et al. 2026a, AJ) has suggested that wide-orbit planet host stars could have super-solar C, O abundances. This potential enrichment in 'volatile' elements is the first empirical evidence that the formation environment around wide-orbit companion host stars is potentially different from other planet host stars.
On the companion front, I am interested in performing a population-level analysis of the C/S and O/S ratios as formation tracers and compare them to similar tracers measured for the transiting planet population. It would be interesting if these ratios clearly segregate the two populations of planets like was seen for the C/O ratio (Hoch et al., 2023, AJ).