NOAO >   Observing Info >   Approved Programs >   2002B-0259

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Proposal Information for 2002B-0259


PI: Soeren Meibom, University of Wisconsin - Madison, meibom@astro.wisc.edu
Address: 475 N. Charter Street, Madison, WI 53706, USA

CoI: Robert Mathieu, University of Wisconsin

Title: The effect of binarity on stellar angular momentum evolution in solar- type stars

Abstract: Angular momentum is a fundamental property of a star that influences its internal structure, distribution of chemical composition, and energy transport. While studies of angular momentum gain and loss in solar- type stars are extensive, few have confronted the role of binary companions, despite the fact that most stars are binaries. In fact, the rotational evolution of a star in a binary can be vastly different from that of a single star. We propose a thesis study on the impact of binary companions on angular momentum evolution of solar-type stars. We will observationally study: 1) rate and evolution of tidal synchronization and pseudo-synchronization; 2) rate and evolution of tidal circularization; and 3) the effect of gaps cleared by companions on magnetic disk locking. We will accomplish this by determining comprehensive photometric rotation period distributions and spectroscopic binary populations in the open clusters NGC2264 (3Myr), M35 (170Myr), and M34 (250Myr). This choice of clusters provides binaries with a sequence of ages during the most active period of tidal angular momentum evolution. A comprehensive photometric time-series study to define the distribution of stellar rotation periods exists for NGC2264 (Makidon et al., in prep.), and are underway for M34 (Barnes & James, in prep) and M35 (Meibom, in prep). We propose to acquire high precision radial velocities and thereby identify binaries and determine orbital solutions for these same stellar samples. These combined datasets will be unique in their ability to address the rich interplay of orbital and rotational angular momentum evolution. Thus this work open a new and rich dimension in the study of angular momentum evolution in solar-type stars.


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