Jeff Valenti (Space Telescope Science Institute): Stellar limb darkening for JWST spectroscopic light curves: theory vs. data

Thursday 20 Feb 2025, 14:00 → 15:00 Europe/Stockholm

80127Å

Title: Stellar limb darkening for JWST spectroscopic light curves: theory vs. data
Speaker: Jeff Valenti
Affiliation: Space Telescope Science Institute
Time: Thursday 20 February 2025, 1400 to 1500
Location: 80127Å

Abstract:

Stellar limb-darkening controls the depth and shape of every transit light curve. Accurate knowledge of limb darkening is essential when measuring the orbital, atmospheric, and bulk properties of transiting exoplanets. Prior to JWST, empirical tests of stellar limb darkening focused mainly on broadband photometric time series (e.g., Kepler, TESS). Now with very precise spectroscopic light curves from JWST, we have the opportunity and a strong need to test models of limb darkening.

I will compare limb-darkening measurements obtained by fitting JWST spectroscopic observations (0.6-5.3 µm) of exoplanet transits with theoretical limb darkening predicted by various stellar atmosphere models, including a 3D MHD model (MURaM + MPS-ATLAS) with various magnetic field strengths. I will show results for a sequence of spectral types (G0, K1, M4), noting differences between predicted and measured limb darkening. I will discuss how limb darkening parameterization and analysis choices can impact limb darkening measurements.