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CONTEXT: High-resolution spectroscopy across spatially resolved stellarsurfaces aims at obtaining spectral-line profiles that are free from rotationalbroadening; the gradual changes of these profiles from disk center toward thestellar limb reveal properties of atmospheric fine structure, which arepossible to model with 3-D hydrodynamics. AIMS: Previous such studies have onlybeen carried out for the Sun but are now extended to other stars. In this work,profiles of photospheric spectral lines are retrieved across the disk of theplanet-hosting star HD209458 (G0V). METHODS: During exoplanet transit, stellarsurface portions successively become hidden and differential spectroscopyprovides spectra of small surface segments temporarily hidden behind theplanet. The method was elaborated in Paper I, with observable signaturesquantitatively predicted from hydrodynamic simulations. RESULTS: Fromobservations of HD209458 with spectral resolution R=80,000, photospheric FeIline profiles are obtained at several center-to-limb positions, reachingadequately high S/N after averaging over numerous similar lines CONCLUSIONS:Retrieved line profiles are compared to synthetic line profiles. Hydrodynamic3-D models predict, and current observations confirm, that photosphericabsorption lines become broader and shallower toward the stellar limb,reflecting that horizontal velocities in stellar granulation are greater thanvertical velocities. Additional types of 3-D signatures will become observablewith the highest resolution spectrometers at large telescopes.

Spatially resolved spectroscopy across stellar surfaces. II. High-resolution spectra across HD209458 (G0V)