PI: Robert Mathieu, University of Wisconsin - Madison, email@example.com
Address: Department of Astronomy, 475 North Charter Street, Madison, WI 53706, USA
CoI: Aaron Geller, University of Wisconsin - Madison
CoI: Natalie Gosnell, University of Wisconsin - Madison
CoI: Andrew Szentgyorgyi, Harvard-Smithsonian Center for Astrophysics
Title: The Formation and Evolution of Blue Stragglers in Open Clusters
Abstract: The dynamical dances that take place during binary encounters in open star clusters lead to stellar exchanges, binary orbit evolution, close stellar passages, mass transfer, mergers, and stellar collisions, resulting in a rich array of ”anomalous” stars such as blue stragglers and sub-subgiants. In order to better understand these new evolutionary paths, we propose observations seeking to detect magnetic fields, secondary stars, and rapid rotation in blue stragglers and other stars of the old open clusters NGC 188, NGC 6819 and NGC 7789. Specifically we propose to use the MMT/Hectochelle at Ca H and K to search for magnetic activity as a proxy for the presence of magnetic fields. These results will reflect directly on the angular momentum evolution of blue stragglers. We also propose to obtain high S/N spectra at the Ca triplet in order to search for main-sequence secondary stars within blue straggler binaries, a critical test of the formation of blue stragglers from triple systems. Finally, we will search for rapidly rotating stars on the main sequences that may be blue straggler analogues resulting from stellar collisions.
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