Tracers of Chromospheric Structure I: Observations of Ca II K and H alpha in M Dwarfs

Details Tracers of Chromospheric Structure I: Observations of Ca II K and H alpha in M Dwarfs Tracers of Chromospheric Structure I: Observations of Ca II K and H alpha in M Dwarfs

2008-11-11

arxiv.org/abs/0811.1778v1

Astronomy and Astrophysics

Astrophysics

25 pages, 16 figures; accepted for publication in the Astronomical Journal

Scientific paper

10.1088/0004-6256/137/2/3297

We report on our observing program to capture simultaneous spectra of Ca II and Balmer lines in a sample of nearby M3 dwarfs. Our goal is to investigate the chromospheric temperature structure required to produce these lines at the observed levels. We find a strong positive correlation between instantaneous measurements of Ca II K and the Balmer lines in active stars, although these lines may not be positively correlated in time-resolved measurements. The relationship between H alpha and Ca II K remains ambiguous for weak and intermediate activity stars, with H alpha absorption corresponding to a range of Ca II K emission. A similar relationship is also observed between Ca II K and the higher order Balmer lines. As our sample consists of a single spectral type, correlations between these important chromospheric tracers cannot be ascribed to continuum effects, as suggested by other authors. These data confirm prior non-simultaneous observations of the H alpha line behavior with increasing activity, showing an initial increase in the H alpha absorption with increasing Ca II K emission, prior to H alpha filling in and eventually becoming a pure emission line in the most active stars. We also compare our optical measurements with archival UV and X-ray measurements, finding a positive correlation between the chromospheric and coronal emission for both high and intermediate activity stars. We compare our results with previous determinations of the active fraction of low mass stars, and discuss them in the context of surface inhomogeneity. Lastly, we discuss the application of these data as empirical constraints on new static models of quiescent M dwarf atmospheres.

Affiliated with

Also associated with

No associations

Rating

Tracers of Chromospheric Structure I: Observations of Ca II K and H alpha in M Dwarfs does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Tracers of Chromospheric Structure I: Observations of Ca II K and H alpha in M Dwarfs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tracers of Chromospheric Structure I: Observations of Ca II K and H alpha in M Dwarfs will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-100197