HST Legacy Archival Program Constraining Stellar Contamination in Transmission Spectroscopy
The HST Stellar Treasure Trove is a large effort to uniformly reprocess archival Hubble Space Telescope time-series spectroscopy of transiting exoplanets and quantify stellar and planetary signals in transmission spectra.
Grant: HST AR 17551 • Last updated: —
Spatially heterogeneous stellar photospheres (spots, faculae, and other active regions) imprint wavelength-dependent signals on measured transit depths. These stellar spectral imprints can bias inferred planetary radii, slopes, and molecular abundances—especially for planets orbiting active K and M dwarfs.
By leveraging the breadth of archival HST transit observations, the Stellar Treasure Trove provides uniform reductions and stellar-contamination constraints, enabling robust comparisons across targets and instruments and supporting interpretation of JWST spectra and future atmospheric surveys.
Quantify the impact of unocculted and occulted heterogeneity on transmission spectra, and provide contamination-aware products designed for downstream atmospheric inference.
Apply consistent reduction and modeling assumptions across a broad sample of HST time-series observations, producing a coherent library for population-level analysis.
Provide constraints and priors that inform JWST interpretation and guide observing strategies for characterizing small planets around active stars.