Topic: Fundamental Parameters of Cool Stars and Brown Dwarfs
Accurate placement in an HR diagram is necessary for the characterization of any stellar, or substellar, population. During the past several years we have measured trigonometric parallaxes and obtained VRI photometry for 105 nearby (d < 25 pc ) objects in the spectral type range M6V to L5. Here we extend the coverage of optical/IR color-magnitude diagrams to provide a continuous sequence for stars like the Sun through the mid L spectral sub-types. We present new trigonometric parallaxes obtained at the CTIO 0.9m telescope through the RECONS (REsearch Consortium On Nearby Stars, www.recons.org) astrometry program, and new VRI photometry obtained at the CTIO 0.9m and SOAR 4m telescopes. We produce new SED fits by combining our optical photometry with infrared photometry from 2MASS and WISE and use the fits to examine trends in temperature and radius across this population. This effort is supported by the U.S. National Science Foundation (NSF) through grant AST-0908402, via observations made possible by the SMARTS Consortium, and is based in part on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Brazilian Ministry of Science and Technology, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill, and Michigan State University.