2008ApJ...675L..37W

We present a strong case for a transiting hot Jupiter planet identified during a single-field transit survey toward the Lupus Galactic plane. The object, Lupus-TR-3b, transits a V=17.4 K1 V host star every 3.91405 days. Spectroscopy and stellar colors indicate a host star with effective temperature 5000±150 K, with a stellar mass and radius of 0.87±0.04 M_☉ and 0.82±0.05 R_☉, respectively. Limb-darkened transit fitting yields a companion radius of 0.89±0.07 R_J and an orbital inclination of 88.3^+1.3_–0.8deg. Magellan 6.5 m MIKE radial velocity measurements reveal a 2.4 σ K = 114±25 m/s sinusoidal variation in phase with the transit ephemeris. The resulting mass is 0.81±0.18 M_J and density 1.4±0.4 g/cm3. Y-band PANIC image deconvolution reveals a V≥21 red neighbor 0.4" away which, although highly unlikely, we cannot conclusively rule out as a blended binary with current data. However, blend simulations show that only the most unusual binary system can reproduce our observations. This object is very likely a planet, detected from a highly efficient observational strategy. Lupus-TR-3b constitutes the faintest ground-based detection to date, and one of the lowest mass hot Jupiters known.