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Arxiv: Using JWST transits and occultations to determine \sim1\% stellar radii and temperatures of low-mass stars Published: 2/8/2024 9:00:00 PM Updated: 2/8/2024 9:00:00 PM

Paper abstract: Using JWST observations of a primary transit and two secondary eclipses forGJ 1214b, we determine an eccentricity that is more precise than a decade ofHARPS data, which enables us to measure the stellar density to 2.62%. Coupledwith a prior on the stellar mass from a dynamically calibrated K-M_*relation, we determine R_* to 1.13% -- 3 times more precise than any otherpublished analysis of this system. Then, using the bolometric flux from an SEDmodel, we determine T_{\rm eff} to 1.39% -- 40% more precise than systematicfloors from spectroscopy. Within the global model, these also improve theplanetary radius and insolation. This is a proof of concept for a new method todetermine accurate R_* and T_{\rm eff} to a precision currently achievedfor only a small number of low-mass stars. By applying our method to all highsignal-to-noise planetary transits and occultations, we can expand the sampleof precisely measured stars without assuming tidal circularization andcalibrate new relations to improve our understanding of all low-mass stars.