* Astronomy

Title: Chromospheric features of LQ Hydrae from H-alpha line profiles
Authors: A. Frasca (1), Zs. Kovari (2), K.G. Strassmeier (3), K. Biazzo (1) ((1) INAF - Catania Astrophysical Observatory, (2) Konkoly Observatory - Budapest, (3) Astrophysical Institute Potsdam)

We analyse the H-alpha spectral variability of the rapidly-rotating K1-dwarf LQ Hya using high-resolution H-alpha spectra recorded during April-May 2000. Chromospheric parameters were computed from the H-alpha profile as a function of rotational phase. We find that all these parameters vary in phase, with a higher chromospheric electron density coinciding with the maximum H-alpha emission. We find a clear rotational modulation of the H-alpha emission that is better emphasized by subtracting a reference photospheric template built up with a spectrum of a non-active star of the same spectral type. A geometrical plage model applied to the H-alpha variation curve allows us to derive the location of the active regions that come out to be close in longitude to the most pronounced photospheric spots found with Doppler imaging applied to the photospheric lines in the same spectra. Our analysis suggests that the H-alpha features observed in LQ Hya in 2000 are a scaled-up version of the solar plages as regards dimensions and/or flux contrast. No clear indication of chromospheric mass motions emerges.

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