NOAO >   Observing Info >   Approved Programs >   2003B-0278

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Proposal Information for 2003B-0278


PI: Soren Meibom, University of Wisconsin - Madison, meibom@astro.wisc.edu
Address: Dept. of Astronomy, 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 stellar angular momentum evolution of solar-type stars. Specifically, we will observationally study: 1) the rate and evolution of tidal synchronization and pseudo-synchronization; 2) the 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 (3 Myr), M35 (150 Myr), and M34 (250 Myr). This choice of clusters provides binaries with ages during the most active period of tidal angular momentum evolution. Extensive photometric time-series observations exist with which to define the distribution of stellar rotation periods for all three clusters. We propose here to acquire high precision radial velocities and thereby identify binaries and determine their orbital parameters. These combined datasets will be unique in their ability to address the rich interplay of orbital and rotational angular momentum. Thus this work will open a new dimension in the study of angular momentum evolution in solar-type stars.


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