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arXiv · 2402.05991

Using JWST transits and occultations to determine $\sim1\%$ stellar radii and temperatures of low-mass stars

Alexandra S. Mahajan·Jason D. Eastman·James Kirk
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Abstract

Using JWST observations of a primary transit and two secondary eclipses for GJ 1214b, we determine an eccentricity that is more precise than a decade of HARPS data, which enables us to measure the stellar density to 2.62%. Coupled with 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 other published analysis of this system. Then, using the bolometric flux from an spectral energy distribution model, we determine $T_{\rm eff}$ to 1.39% -- 40% more precise than systematic floors from spectroscopy. Within the global model, these also improve the planetary radius and insolation. This is a proof of concept for a new method to determine accurate $R_*$ and $T_{\rm eff}$ to a precision currently achieved for only a small number of low-mass stars. By applying our method to all high signal-to-noise ratio planetary transits and occultations, we can expand the sample of precisely measured stars without assuming tidal circularization and calibrate new relations to improve our understanding of all low-mass stars.

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Alexandra S. Mahajan, Jason D. Eastman, James Kirk. 2024-02-08. Using JWST transits and occultations to determine $\sim1\%$ stellar radii and temperatures of low-mass stars. https://doi.org/10.3847/2041-8213%2Fad29f3

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