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Paper: Applied Doppler Imaging: Can Magnetic Activity of IM Pegasi Affect the Gravity Probe B Mission?
Volume: 358, Solar Polarization 4
Page: 385
Authors: Berdyugina, S.V.; Marsden, S.C.
Abstract: IM Peg is a single-lined, spectroscopic RS CVn binary, with a rapidly rotating (v sin i = 27 km/s), early K-type, giant primary. Magnetic activity of the primary is indicated by dark spots covering >15% of the surface. The system is bright in both optical and radio, and was chosen as a guide star for the Gravity Probe B (GP-B) satellite mission. The goal of GP-B is to verify two predictions of Einstein's theory of general relativity (geodetic effect and “frame dragging”), based on measurements of mean gyroscopic drift with respect to the optical centroid of IM Peg. The requested precision of 0.5 × 10−3 arcsec/yr implies that even small shifts of the optical centroid of IM Peg due to surface magnetic activity must be determined. In support of the GP-B mission, we are undertaking an intensive Doppler imaging survey of the primary component of IM Peg, to determine the effect of spot features on its optical centroid. We present an overview of our work for GP-B, and report initial results from this support project, including the first magnetic maps of the IM Peg primary, created using Least-Squares Deconvolution and Zeeman Doppler Imaging.
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