Computer Science
Scientific paper
Aug 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005noao.prop...84g&link_type=abstract
NOAO Proposal ID #2005B-0084
Computer Science
Scientific paper
The calibration of the empirical relation between Ca II chromospheric strength and stellar age between 0.6 Gyr (Hyades) and 4.0 - 5 Gyr (M67 and the Sun) relies on the uncertain determination of ages for individual field stars in the solar neighborhood. We therefore propose to obtain WIYN/Hydra spectra of ~ 100 solar-type dwarf stars in the 1.8 Gyr old open cluster, NGC 752. This cluster contains a sample of solar-type dwarfs that is homogeneous in age and chemical composition. Furthermore, NGC 752 is the nearest-and hence brightest- cluster at an age ~ 2 Gyr. The results will yield an improved calibration of the age-activity relation at intermediate ages. In addition, we will determine if the chromospheric Ca II strengths for the solar-type stars in NGC 752 lie in the so-called "Vaughan-Preston Gap''- an apparent discontinuity in the Ca II H& K strength-(B-V) diagram found for field stars in the solar neighborhood. Our data will yield insight on the two proposed origins for the gap, namely, that it is a result of two different modes of dynamo action or that it is actually an artifact of a discontinuity in the local star formation rate. This is a resubmission of a previously approved proposal that was allocated two nights in 2004 November. The time was lost to instrument problems (Hydra gripper malfunctions) and weather. No usable data were obtained.
Deliyannis Constantine
Giampapa Mark
Sherry William
Stauffer John
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