New Red Jewels in Coma Berenices

Ryan C. Terrien, Suvrath Mahadevan, Rohit Deshpande, Chad F. Bender, Phillip A. Cargile, Frederick R. Hearty, Michiel Cottaar, Carlos Allende Prieto, Scott W. Fleming, Peter M. Frinchaboy, Kelly M. Jackson, Jennifer A. Johnson, Steven R. Majewski, David L. Nidever, Joshua Pepper, Joseph E. Rodriguez, Donald P. Schneider, Robert J. Siverd, Keivan G. Stassun, Benjamin A. Weaver, John C. Wilson

Published 2014-01-06Version 1

We have used Sloan Digital Sky Survey-III (SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) radial velocity observations in the near-infrared $H$-band to explore the membership of the nearby ($86.7 \pm 0.9$ pc) open cluster Coma Berenices (Melotte 111), concentrating on the poorly-populated low-mass end of the main sequence. Using SDSS-III APOGEE radial velocity measurements, we confirm the membership of eight K/M dwarf members, providing the first confirmed low-mass members of the Coma Berenices cluster. Using $R\sim2000$ spectra from IRTF-SpeX, we confirm the independently luminosity classes of these targets, and find their metallicities to be consistent with the known solar mean metallicity of Coma Berenices and of M dwarfs in the Solar neighborhood. In addition, the APOGEE spectra have enabled measurement of $v\sin i$ for each target and detection for the first time of the low-mass secondary components of the known binary systems Melotte 111 102 and Melotte 111 120, as well as identification of the previously unknown binary system 2MASS J12214070+2707510. Finally, we use Kilodegree Extremely Little Telescope (KELT) photometry to measure photometric variability and rotation periods for a subset of the Coma Berenices members.