AAS 204th Meeting, June 2004
Session 3 Stellar-Solar Connection
SPD Poster, Monday, May 31, 2004, 9:20am-6:30pm, Ballroom

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[3.02] The Distribution and Variability of Chromospheric Activity in a Large Sample of Solar Analogs

J. C. Hall, G. W. Lockwood (Lowell Observatory)

We present the results of approximately 9,000 spectroscopic observations of the chromospheric Ca II H&K emission in a magnitude-limited sample of solar analog stars, as well as nearly 1,000 identical observations of the Sun, taken between 1994 and 2003. We discuss the behavior of Ca variations in the nearest solar analogs relative to the contemporaneous solar record, reconcile our flux measurements with Ca K indices from the NSO as well as Mt. Wilson S, and examine the general activity level in cycling versus non-cycling stars.

Although approximately one third of the stars in the sample show little or no long-term cyclic variability, we find that a lack of such variability does not imply very low levels of magnetic activity. Non-cycling stars exhibit a variety of baseline activity levels, from near-zero magnetic activity to levels comparable to that of the active Sun. We do not find significant evidence for transitions to or from a Maunder minimum state in our current stellar sample, or that such transitions are accompanied by a significant change in a star's overall activity level.

This work has been supported by the National Science Foundation.

The author(s) of this abstract have provided an email address for comments about the abstract: jch@lowell.edu

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