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

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

Solar and Stellar Astrophysics 2010-12-17 v1 Earth and Planetary Astrophysics

Authors: J. Gomes da Silva , N. C. Santos , X. Bonfils

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.

Keywords

stellar activity M-dwarf chromospheric activity indicator HARPS correlation analysis

Cite

@article{arxiv.1012.3640,
  title  = {Long-term stellar activity variations of stars from the HARPS M-dwarf sample: Comparison between activity indices},
  author = {J. Gomes da Silva and N. C. Santos and X. Bonfils},
  journal= {arXiv preprint arXiv:1012.3640},
  year   = {2010}
}

Comments

6 pages, 3 figures, 1 table, Proceedings of the 16th Workshop on Cool Stars, Stellar Systems, and the Sun (Seattle, WA, Aug 29 - Sep 2, 2010)

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