NOAO >   Observing Info >   Approved Programs >   2013B-0294

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Proposal Information for 2013B-0294


PI: Rachael M. Roettenbacher, University of Michigan, rmroett@umich.edu
Address: Department of Astronomy, 500 Church Street, Ann Arbor, MI 48109, USA

CoI: John D. Monnier, University of Michigan
CoI: Robert O. Harmon, Ohio Wesleyan University
CoI: Heidi Kornhonen, Niels Bohr Institute

Title: Resolving the Spotted Surface of \zeta And with Simultaneous Interferometric, Doppler, and Photometric Imaging

Abstract: We propose to image directly the complicated spot structures of the magnetically active, K-giant \zeta Andromedae (\zeta And, P_\mathrmorb=17.77 days) by combining state-of-the-art infrared interferometric imaging, Doppler imaging, and light-curve inversion techniques in a coordinated effort. \zeta And is one of the brightest (V=4.04) and nearest (58 pc) RS CVn stars. With a large angular size, high v \sin i, and consistent large photometric variations indicative of the constant presence of spot structures, \zeta And lends itself well to being studied with these three methods. We will obtain interferometric images of \zeta And with the upgraded Michigan Infrared Combiner (MIRC) at the CHARA Array on Mount Wilson using all six telescopes, for which we have been awarded eighteen nights of observation. In order to verify this new method of stellar-surface imaging, it is necessary to compare this direct image with a high- fidelity surface reconstructions provided by Doppler imaging and light- curve inversion techniques. The comparison between these techniques is crucial for studying any systematic differences between the methods and paving the way for fully complementary use of these methods in studying stellar surface structures. Here, we propose to obtain high-quality, multi-filter photometry over the full rotation of \zeta And using the 1.3m CTIO telescope with ANDICAM. With a full-rotation-period light curve, we will be able to accurately reconstruct the spotted stellar surface and settle long-standing controversies, such as the nature of the cool polar spots produced in Doppler images.


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