NOAO >   Observing Info >   Approved Programs >   2002A-0225

Small NOAO Logo

Proposal Information for 2002A-0225


PI: Mihalis Mathioudakis, Queens University of Belfast, M.Mathioudakis@qub.ac.uk
Address: Belfast BT7 1NN, Northern Ireland

CoI: Damian Christian, John Hopkins University

Title: A search for supersaturation in stellar chromospheres

Abstract: The rotation-activity relations of late-type stars exhibit the effects of saturation in the chromospheric and coronal emission. Recent X-ray observations have shown that ultra fast rotators (vsini > 30 km sec^-1) show a decline in their coronal emission. This effect is called \em super-saturation. Theoretical models predict that as the increased rotational velocity decreases the apparent surface gravity, the hot coronal plasma becomes unstable and cools down to chromospheric temperatures. More cool loops emitting in chromospheric lines can exist but not in X-rays. We propose to observe the chromospheric lines of Ca II H&K and hydrogen Balmer, in a group of EUV/X-ray selected active late-type stars. The rotational periods of these objects are in excess of 10 km s^-1. The requested observations will allow us to test the model predictions.


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



NOAO >   Observing Info >   Approved Programs >   2002A-0225

noaoprop-help@noao.edu

Small NOAO Logo