A clever idea: use the area covered by a transiting exoplanet to get a narrow band stellar spectrum from a rapidly rotating star! Secrets in the shadow: High precision stellar abundances of fast-rotating A-type exoplanet host stars through transit spectroscopy by Lam+ 🪐🔭 #astrodon

A combination of broad line spectra from a rotationally broadened star and the narrow emission from the area of the star blocked by the exoplanet in transit.A figure showing the star blocked by the planet, and the resultant spectrum, and then a figure with a Doppler shifted stellar surface showing how the velocity shift moves the planet selected spectrum of the star to one side.

Matthew Kenworthy @kenworthy