The TRENDS High-Contrast Imaging Survey. II. Direct Detection of the HD   8375 Tertiary
  We present the direct imaging detection of a faint tertiary companion to the single-lined spectroscopic binary HD 8375 AB. Initially noticed as an 53 m/s/yr Doppler acceleration by Bowler et al. 2010, we have obtained high-contrast adaptive optics observations at Keck using NIRC2 that spatially resolve HD 8375 C from its host(s). Astrometric measurements demonstrate that the companion shares a common proper-motion. We detect orbital motion in a clockwise direction. Multiband relative photometry measurements are consistent with a spectral-type of M1V. Our combined Doppler and imaging observations place a lower-limit of m>0.297Msun on its dynamical mass. We also provide a refined orbit for the inner pair using recent RV measurements obtained with HIRES. HD 8375 is one of many triple-star systems that are apparently missing in the solar neighborhood. 
Justin R. Crepp, John Asher Johnson, Andrew W. Howard, Geoff W. Marcy,   Debra A. Fischer, Scott M. Yantek, Jason T. Wright,...
astro-ph.EP astro-ph.SR