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Paper: The Effects of Close Companions on the Magnetic Activity of M Dwarfs
Volume: 448, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun
Page: 1195
Authors: Morgan, D. P.; West, A. A.; Silvestri, N. M.
Abstract: We present a study of close white dwarf and M dwarf (WD+dM) binary systems that examines the effects that close companions have on magnetic field generation in M dwarfs. We used a base sample of 1602 white dwarf — main seqeuence (WDMS) binaries from Rebassa-Mansergas et al. to determine a set of color cuts in u, g, r, i, and z. Then using the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) we constructed a sample of 2292 WD+dM pairs. We separated the dM and WD from each combined spectrum using an iterative technique that compared the WD and dM components to best-fit templates. Using the absolute height above the Galactic Plane as a proxy for age, and the Hα emission line as an indicator for magnetic activity, we investigated the age-activity relation for our sample; spectral types ≤M5. Our results show that early-type M dwarfs in close binary systems have increased magnetic activity in both magnitude and duration compared to their field counterparts. However, we begin to see a transition at spectral type M5 (just past the onset of full convection in M dwarfs), where the magnitude and duration in close WD+dM binary systems become more comparable to that of the field M dwarfs.
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