Planets orbiting other stars could in principle be found through the periodic dimming of starlight as a planet moves across--or 'transits'--the line of sight between the observer and the star. Depending on the size of the planet relative to the star, the dimming could reach a few per cent of the apparent brightness of the star. Despite many searches, no transiting planet has been discovered in this way; the one known transiting planet--HD209458b--was first discovered using precise measurements of the parent star's radial velocity and only subsequently detected photometrically. Here we report radial velocity measurements of the star OGLE-TR-56, which was previously found to exhibit a 1.2-day transit-like light curve in a survey looking for gravitational microlensing events. The velocity changes that we detect correlate with the light curve, from which we conclude that they are probably induced by an object of around 0.9 Jupiter masses in an orbit only 0.023 au from its star. We estimate the planetary radius to be around 1.3 Jupiter radii and its density to be about 0.5 g x cm(-3). This object is hotter than any known planet (approximately 1,900 K), but is still stable against long-term evaporation or tidal disruption.

We report high-resolution spectroscopic follow-up observations of the faint transiting planet candidate OGLE-TR-33 (V ¼ 14:7), located in the direction of the Galactic center. Small changes in the radial velocity of the star were detected that initially suggested the presence of a large planet or brown dwarf in orbit. However, further analysis revealed spectral line asymmetries that change in phase with the 1.95 day period, casting doubt on those measurements. These asymmetries make it more likely that the transit-like events in the light curve are the result of contamination from the light of an eclipsing binary along the same line of sight (referred to as a ''blend''). We performed detailed simulations in which we generated synthetic light curves resulting from such blend scenarios and fitted them to the measured light curve. Guided by these fits and the inferred properties of the stars, we uncovered a second set of lines in our spectra that correspond to the primary of the eclipsing binary and explain the asymmetries. Using all the constraints from spectroscopy, we were then able to construct a model that satisfies all the observations and to characterize the three stars based on model isochrones. OGLE-TR-33 is fully consistent with being a hierarchical triple system composed of a slightly evolved F6 star (the brighter object) near the end of its main-sequence phase and an eclipsing binary with a K7-M0 star orbiting an F4 star. The application to OGLE-TR-33 of the formalism developed to fit light curves of transit candidates illustrates the power of such simulations for predicting additional properties of the blend and for guiding further observations that may serve to confirm that scenario, thereby ruling out a planet. Tests such as this can be very important for validating faint candidates.

We present measurements of the true masses and orbital inclinations of the two Earth-mass planets in the PSR B1257+12 system, based on the analysis of their mutual gravitational perturbations detectable as microsecond variations of the arrival times of radio pulses from the pulsar. The 6.2-millisecond pulsar, PSR B1257+12, has been regularly timed with the Arecibo telescope since late 1990. Assuming the standard pulsar mass of 1.4 M ⊙ , the derived masses of planets B and C are 4.3±0.2M ⊕ and 3.9±0.2M ⊕ , respectively. The corresponding orbital inclinations of 53 • ±4 • and 47 • ±3 • (or 127 • and 133 • ) imply that the two orbits are almost coplanar. This result, together with the known near 3:2 resonance between the orbits of the two planets, strongly supports the hypothesis of a disk origin of the PSR B1257+12 planetary system. The system's long-term stability is guaranteed by the low, Earth-like masses of planets B and C.

We report the discovery of a substellar-mass companion to the K0 giant HD 17092 with the Hobby-Eberly Telescope. In the absence of any correlation of the observed 360 day periodicity with the standard indicators of stellar activity, the observed radial velocity variations are most plausibly explained in terms of a Keplerian motion of a planetary-mass body around the star. As the estimated stellar mass is 2.3 M , the minimum mass of the planet is 4.6 M J . The planet's orbit is characterized by a mild eccentricity of e ¼ 0:17 and a semimajor axis of 1.3 AU. This is the tenth published detection of a planetary companion around a red giant star. Such discoveries add to our understanding of planet formation around intermediate-mass stars, and they provide dynamical information on the evolution of planetary systems around post-main-sequence stars. Subject headingg s: planetary systems -stars: individual ( HD 17092)

We report the independent discovery of a new extrasolar transiting planet around OGLE-TR-113, a candidate star from the Optical Gravitational Lensing Experiment. Small radial velocity variations have been detected based on observations conducted with the MIKE spectrograph on the Magellan I (Baade) telescope at the Las Campanas Observatory (Chile) during 2003. We have also carried out a light-curve analysis incorporating new photometry and realistic physical parameters for the star. OGLE-TR-113b has an orbital period of only 1.43 days, a mass of , and a radius of . Similar parameters have been obtained very recently in an (1.08 ‫ע‬ 0.28)M(1.09 ‫ע‬ 0.10)R Jup Jup independent study by Bouchy et al., from observations taken a year later. The orbital period of OGLE-TR-113b and the previously announced planet OGLE-TR-56b ( days)-the first two found photometrically-P p 1.21 orb are much shorter than the apparent cutoff of close-in giant planets at 3-4 day periods found in high-precision radial velocity surveys. Along with a third case reported by Bouchy et al. (OGLE-TR-132b, days), P p 1.69 orb these objects appear to form a new class of "very hot Jupiters" that pose very interesting questions for theoretical study.