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| Paper: |
Convective Parameters and Activity in Late-Type Giants |
| Volume: |
154, Cool Stars, Stellar Systems and the Sun: Tenth Cambridge Workshop |
| Page: |
827 |
| Authors: |
Dorado, Myriam; Montesinos, Benjamin |
| Abstract: |
In this paper we present the computation of some convective parameters, for models with masses in the range between 1.19 and 5.90 M_odot. We also study the evolution of these parameters with the stellar age, trying to establish correlations between their behaviours. We have also plotted in a HR diagram six tracks corresponding to models with masses in the above interval along with a sample of 79 late-type giants, for which the absolute luminosities have been computed making use of the parallax data from the Hipparcos mission. These stars have been selected among those showing activity, since the current study is focused towards a deeper understanding of the phenomena that give origin to stellar activity and magnetism in this kind of star. We have done an inspection of their IUE spectra, which allows us to discriminate between coronal stars and stars showing only chromosphere. Using the evolutionary tracks, we show whether the position of a given star coincides with episodes in which a convection zone has developed. To our surprise, we have found a group of stars --- all of them rapid rotators --- placed in an area of the HR diagram where the convective zone has not developed yet. If this is real, this fact contradicts the paradigm that convection and rotation are essential elements for the presence of activity. |
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