The Astrophysical Journal, 694:1085–1098, 2009 April 1 doi:10.1088/0004-637X/694/2/1085 C 2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A. DIRECTLY DETERMINED LINEAR RADII AND EFFECTIVE TEMPERATURES OF EXOPLANET HOST STARS Gerard T. van Belle1 and Kaspar von Braun2 1 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany;
[email protected] 2 NASA Exoplanet Science Institute, California Institute of Technology, MC 100-22, Pasadena, CA 91125, USA;
[email protected] Received 2008 October 15; accepted 2008 December 31; published 2009 March 23 ABSTRACT We present interferometric angular sizes for 12 stars with known planetary companions, for comparison with 28 additional main-sequence stars not known to host planets. For all objects we estimate bolometric fluxes and red- denings through spectral-energy distribution (SED) fits, and in conjunction with the angular sizes, measurements of effective temperature. The angular sizes of these stars are sufficiently small that the fundamental resolution limits of our primary instrument, the Palomar Testbed Interferometer, are investigated at the sub-milliarcsecond level and empirically established based upon known performance limits. We demonstrate that the effective tem- perature scale as a function of dereddened (V − K)0 color is statistically identical for stars with and without planets. A useful byproduct of this investigation is a direct calibration of the TEFF scale for solarlike stars, as − ∆ − = a function of both spectral type and (V K)0 color, with an precision of T (V K)0 138 K over the range (V − K)0 = 0.0–4.0 and ∆T SpType = 105 K for the range F6V–G5V.