Impacts on Planet Formation: Planet Occurrence rates in the Metal-Poor Regime

Planet formation models predict that below a certain protoplanetary disk metallicity, the surface density of solid material is too low to form planets. Observationally, previous works have indicated that short-period planets preferentially form around stars with solar and super solar metallicities. Given these findings, it is challenging to form planets within metal-poor environments. Due to the target selection process of previous surveys, there is little constraint on planet occurrence rates below [Fe/H] ~ -0.5, which is still higher than the predicted metallicity at which planet formation cannot occur. Expanding upon previous works, we construct a large sample of ~100,000 metal-poor stars with spectroscopically-derived stellar parameters observed by TESS. With such a large sample, we probe planet formation within the metal-poor regime (-2.0 ≤ [Fe/H] ≤ -0.5) placing the most stringent upper limits on planet occurrence rates around metal-poor stars.