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The theoretically studied impact of rapid rotation on stellar evolution needsto be confronted with the results of high resolution spectroscopy-velocimetryobservations. A weak surface magnetic field had recently been detected in theA0 prototype star Vega, potentially leading to a (yet undetected) structuredsurface. The goal of this article is to present a thorough analysis of the lineprofile variations and associated estimators in the early-type standard starVega (A0) in order reveal potential activity tracers, exoplanet companions andstellar oscillations. Vega was monitored in high-resolution spectroscopy withthe velocimeter Sophie/OHP. A total of 2588 high S/N spectra was obtainedduring 5 nights (August 2012) at R = 75000 and covering the visible domain. Foreach reduced spectrum, Least Square Deconvolved (LSD) equivalent photosphericprofiles were calculated with a Teff = 9500 and logg = 4.0 spectral line mask.Several methods were applied to study the dynamic behavior of the profilevariations (evolution of radial velocity, bisectors, vspan, 2D profiles,amongst others). We present the discovery of a starspotted stellar surface inan A-type standard star with faint spot amplitudes Delta F/Fc ~5 10^{-4}. Arotational modulation of spectral lines with a period of rotation P = 0.68 dhas clearly been exhibited, confirming the results of previousspectropolarimetric studies. Either a very thin convective layer can beresponsible for magnetic field generation at small amplitudes, or a newmechanism has to be invoked in order to explain the existence of activitytracing starspots. This first strong evidence that standard A-type stars canshow surface structures opens a new field of research and asks the questionabout a potential link with the recently discovered weak magnetic fielddiscoveries in this category of stars.

Discovery of starspots on Vega - First spectroscopic detection of surface structures on a normal A-type star