NOAO >   Observing Info >   Approved Programs >   2003B-0342

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Proposal Information for 2003B-0342


PI: Gaitee A.J. Hussain, Harvard Smithsonian CfA, ghussain@cfa.harvard.edu
Address: SSP Division, 60 Garden St, MS-16, Cambridge, MA 02138, USA

CoI: Steven H. Saar, Harvard Smithsonian CfA

Title: Looking for photospheric saturation in the (alpha) Per cluster

Abstract: A key tracer of magnetic activity in cool stars, X-ray emission, can be used to gauge how active a star is. Generally speaking, rapidly rotating stars emit the most in X-rays and so are deemed to be the most magnetically active stars. However, surveys of young open clusters have revealed that the most rapidly rotating cool stars actually show a decline in X-ray emission, a phenomenon known as super-saturation. We want to learn whether these \em super-saturated stars actually are less magnetically active or whether some other process is responsible for this effect. We will look at how surface magnetic activity depends on rotation rate and spectral type. We will measure spot coverage in rapid rotators in the young (alpha) Per cluster using molecular bands that only form at cool spot temperatures. These spot measurements will be used as surface magnetic activity tracers and enable us to learn how surface activity depends on different stellar parameters. This will enable us to distinguish between conflicting theories of X-ray activity in cool stars.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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