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Published on 04 September 2018
Vol. 616
In section 8. Stellar atmospheres
Spatially resolved spectroscopy across stellar surfaces. III. Photospheric FeI lines across HD189733A (K1 V)
by D. Dravins, M. Gustavsson, and H.-G. Ludwig A&A 616, A144
This paper presents spatially resolved, high spectral-resolution
spectroscopy with the ESO HARPS, of photospheric Fe I lines over the stellar
surface of the cool planet-hosting K1 V star, HD 189733A. This is possible
during an exoplanet transit as successive portions of the stellar surface
become hidden, and differential spectroscopy between these various transit
phases provides spectra of small surface segments temporarily hidden behind
the planet. This provides spectral line profiles that are free from rotational
broadening, and so their gradual change from the center towards the stellar
limb reflects the fine structure in the stellar atmosphere. These
observations are compared to 3D hydrodynamic models to explore fine
structure and 3D line formation in the atmosphere of this star. This
detailed understanding is important to enable future searches for
Earth-analogue exoplanets around K-type stars, where the more tranquilsurface granulation and lower ensuing micro-variability may allow suchdetections.