![\begin{figure}
\par\includegraphics[width=8.8cm,clip]{Hh223_f1.eps}\end{figure}](/articles/aa/full/2005/45/aahh223/Timg20.gif) |
Figure 1:
HARPS spectra of the Ca II H
(
)
line region for Gl 581 and three comparison
stars with similar spectral type and apparent magnitude. The stars are
displayed in order of ascending chromospheric activity, and from top to
bottom are Gl 752A, Gl 908, Gl 832 and Gl 581. The chromospheric
emission peaks look prominent against the weak blue continuum of these
M dwarfs, but they actually denote very weak chromospheric emission relative
to the bolometric luminosity. Amongst those 4 stars, Gl 581 has the
weakest chromospheric activity.
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