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arXiv · 1012.3640

Long-term stellar activity variations of stars from the HARPS M-dwarf sample: Comparison between activity indices

J. Gomes da Silva·N. C. Santos·X. Bonfils
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Abstract

We used four known chromospheric activity indicators to measure long-term activity variations in a sample of 23 M-dwarf stars from the HARPS planet search program. We compared the indices using weighted Pearson correlation coefficients and found that in general (i) the correlation between $S_{CaII}$ and \ion{Na}{i} is very strong and does not depend on the activity level of the stars, (ii) the correlation between our $S_{CaII}$ and H$\alpha$ seems to depend on the activity level of the stars, and (iii) there is no strong correlation between $S_{CaII}$ and \ion{He}{i} for these type of stars.

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J. Gomes da Silva, N. C. Santos, X. Bonfils. 2010-12-16. Long-term stellar activity variations of stars from the HARPS M-dwarf sample: Comparison between activity indices. https://arxiv.org/abs/1012.3640

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