Modelos atmosféricos de estrellas de tipo solar

VIEYTES, M. C.; MAUAS, P.J.D.

Argentina

Congreso; Boletín de la Asociación Argentina de Astronomía; 2003

Asociación Argentina de Astronomía

We compare chromospheric models of the Sun (B-V=0.65) as a star, with ten solar analogs with 0.62 < B-V < 0.68. Those stars are (in ascending activity level order) HD187923, HD172051, HD146233 (the best solar twin to date), HD 19467, HD 197076, HD 189567, HD 20766, HD 30495, HD 1835 and HD 202917, where the latest four stars conform the most active stars group. The models are constructed to fit the H and K Ca II and Hβ lines, ingincluding the asimetry of the lines due to macroscopy velocity fields. To test our models, we compare other lines (Balmer series, b Mg I lines and d Na I lines) with observations obtaining good agreement. These stars have a wide variety of magnetic activity levels, so we study differences among their atmospheric structures. We found for the less active stars that the changes with activity are in the region of the temperature minimum, while the most active stars show changes all along their atmospheric structures, mainly in the upper chromosphere. Regarding the macroscopy velocity fields, we can distinguish between the two groups. The most active group have a velocity field in the minimum-temperature region, and the other group in the chromospheric plateau. From these models we can estimate the amount of energy to support these atmospheric structures, to constrain the physical processes responsible for the chromospheric heating.