NOAO >   Observing Info >   Approved Programs >   2001B-0213

Small NOAO Logo

Proposal Information for 2001B-0213


PI: Catrina M. Hamilton, Wesleyan University, catrina@astro.wesleyan.edu
Address: Van Vleck Observatory, Middletown, CT 06459, USA

CoI: William Herbst, Wesleyan University
CoI: Katherine L. Rhode, Yale University
CoI: Robert D. Mathieu, University of Wisconsin

Title: Rotational Velocities and Radii of Pre-Main Sequence Stars in NGC 2264

Abstract: We wish to obtain high dispersion spectra for about 300 pre-main sequence (PMS) stars in NGC 2264 in order to measure v\thinspace sin(i) values. In a study conducted by Rhode et al. (2001), it was found that the average value of sin(i) for PMS stars in the Orion Nebula Cluster (ONC) is lower than the expected value of \pi/4. We wish to explore the possible causes for this discrepancy by measuring v\thinspace sin(i) values for stars in a different cluster. Our sample includes ~ 150 stars brighter than V=16 for which accurate rotation periods are known from photometric monitoring. An additional 150 stars will serve as a control sample to ascertain whether the rotational properties of stars with and without periodic spot variations are identical. By combining rotation periods with projected velocities for this large sample of stars, we will also be able to apply statistical arguments to arrive at estimates for the mean radii of the stars in NGC 2264. Stellar radii and rotational velocities are crucial fundamental parameters which constrain theoretical models describing PMS evolution. However, with the exception of three known PMS eclipsing binaries, we have no direct measurement of the sizes of PMS stars. Our method for the estimation of sin(i) and stellar radii will be that which has been successfully employed by Rhode, Herbst, and Mathieu (2001) in the ONC.


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 >   2001B-0213

noaoprop-help@noao.edu

Small NOAO Logo