We present six new transits of the exoplanet OGLE-TR-111b observed with the Magellan Telescopes in Chile between 2008 April and 2009 March. We combine these new transits with five previously published transit epochs for this planet between 2005 and 2006 to extend the analysis of transit timing variations (TTVs) reported for this system. We derive a new planetary radius value of 1.019+/-0.026R_J_, which is intermediate to the previously reported radii of 1.067+/-0.054R_J_ and 0.922+/-0.057R_J_. We also examine the TTV and duration change claims of Diaz et al. (2008ApJ...682L..49D). Our analysis of all 11 transit epochs does not reveal any points with deviations larger than 2{sigma}, and most points are well within 1{sigma}. Although the transit duration nominally decreases over the four year span of the data, systematic errors in the photometry can account for this result. Therefore, there is no compelling evidence for either a timing or a duration variation in this system. Numerical integrations place an upper limit of about 1M_{earth}_ on the mass of a potential second planet in a 2:1 mean-motion resonance with OGLE-TR-111b.
We report the results of the first transit timing variation analysis of the very hot Jupiter OGLE-TR-132b, using 10 transits collected over a seven-year period. Our analysis combines three previously published transit light curves with seven new transits, which were observed between 2008 February and 2009 May with the new MagIC-e2V instrument on the Magellan Telescopes in Chile. We provide a revised planetary radius of R_p_=1.23+/-0.07R_J_, which is slightly larger, but consistent within the errors, than that given by previously published results. Analysis of the planet-to-star radius ratio, orbital separation, inclination, and transit duration reveals no apparent variation in any of those parameters during the time span observed. We also find no sign of transit timing variations larger than -108+/-49s, with most residuals very close to zero. This allows us to place an upper limit of 5-10M_{earth}_ for a coplanar, low-eccentricity perturber in either the 2:1 or 3:2 mean-motion resonance with OGLE-TR-132b. We similarly find that the data are entirely consistent with a constant orbital period and there is no evidence for orbital decay within the limits of precision of our data.
We report the discovery of one newly confirmed planet (P=66.06 days, R_P_=2.68+/-0.17 R_{Earth}_) and mass determinations of two previously validated Kepler planets, Kepler-289 b (P=34.55 days, R_P_=2.15+/-0.10 R_{Earth}_) and Kepler-289-c (P=125.85 days, R_P_=11.59+/-0.10 R_{Earth}_), through their transit timing variations (TTVs). We also exclude the possibility that these three planets reside in a 1:2:4 Laplace resonance. The outer planet has very deep (~1.3%), high signal-to-noise transits, which puts extremely tight constraints on its host star's stellar properties via Kepler's Third Law. The star PH3 is a young (~1 Gyr as determined by isochrones and gyrochronology), Sun-like star with M_*_=1.08+/-0.02 M_{sun}_, R_*_=1.00+/-0.02 R_{sun}_, and T_eff_=5990+/-38 K. The middle planet's large TTV amplitude (~5 hr) resulted either in non-detections or inaccurate detections in previous searches. A strong chopping signal, a shorter period sinusoid in the TTVs, allows us to break the mass-eccentricity degeneracy and uniquely determine the masses of the inner, middle, and outer planets to be M=7.3+/-6.8 M_{oplus}_, 4.0+/-0.9M_{oplus}_, and M=132+/-17 M_{oplus}_, which we designate PH3 b, c, and d, respectively. Furthermore, the middle planet, PH3 c, has a relatively low density, {rho}=1.2+/-0.3 g/cm3 for a planet of its mass, requiring a substantial H/He atmosphere of 2.1_-0.3_^+0.8^% by mass, and joins a growing population of low-mass, low-density planets.
We present new photometry of HD 149026 spanning five transits of its "super-Neptune" planet. In combination with previous data, we improve on the determination of the planet-to-star radius ratio: Rp/R_*_=0.0491^+0.0018^_-0.0005_. We find the planetary radius to be 0.71+/-0.05R_{Jup}_, in accordance with previous theoretical models invoking a high metal abundance for the planet. The limiting error is the uncertainty in the stellar radius. Although we find agreement among four different ways of estimating the stellar radius, the uncertainty remains at 7%. We also present a refined transit ephemeris and a constraint on the orbital eccentricity and argument of pericenter, ecos{omega}=-0.0014+/-0.0012 , based on the measured interval between primary and secondary transits.
We present transit photometry of three exoplanets, TrES-4b, HAT-P-3b, and WASP-12b, allowing for refined estimates of the systems' parameters. TrES-4b and WASP-12b were confirmed to be "bloated" planets, with radii of 1.706+/-0.056R_Jup_ and 1.736+/-0.092R_Jup_, respectively. These planets are too large to be explained with standard models of gas giant planets. In contrast, HAT-P-3b has a radius of 0.827+/-0.055R_Jup_, smaller than a pure hydrogen-helium planet and indicative of a highly metal-enriched composition. Analyses of the transit timings revealed no significant departures from strict periodicity. For TrES-4, our relatively recent observations allow for improvement in the orbital ephemerides, which is useful for planning future observations.
We report the discovery of photometric oscillations in the host star of the exoplanet WASP-33b (HD 15082). The data were obtained in the R band in both transit and out-of-transit phases from the 0.3-m telescope and the Montcabrer Observatory and the 0.8-m telescope at the Montsec Astronomical Observatory. Proper fitting and subsequent removal of the transit signal reveals stellar photometric variations with a semi-amplitude of about 1mmag. The detailed analysis of the periodogram yields a structure of significant signals around a frequency of 21 cyc per day, which is typical of delta Scuti-type variable stars. An accurate study of the power spectrum reveals a possible commensurability with the planet orbital motion with a factor of 26, but this remains to be confirmed with additional time-series data that will permit the identification of the significant frequencies. These findings make WASP-33 the first transiting exoplanet host star with delta Scutt variability and a very interesting candidate to search for star-planet interactions.
We present new ground-based, multi-colour, broad-band photometric measurements of the physical parameters, transmission and emission spectra of the transiting extrasolar planet WASP-19b. The measurements are based on observations of eight transits and four occultations through a Gunn i filter using the 1.54-m Danish Telescope, 14 transits through an Rc filter at the Perth Exoplanet Survey Telescope (PEST) observatory and one transit observed simultaneously through four optical (Sloan g', r', i', z') and three near-infrared (J, H, K) filters, using the Gamma Ray Burst Optical and Near-Infrared Detector (GROND) instrument on the MPG/ESO 2.2-m telescope. The GROND optical light curves have a point-to-point scatter around the best-fitting model between 0.52 and 0.65 mmag rms. We use these new data to measure refined physical parameters for the system. We find the planet to be more bloated (R_b_=1.410+/-0.017R_Jup_; M_b_=1.139+/-0.030M_Jup_) and the system to be twice as old as initially thought. We also used published and archived data sets to study the transit timings, which do not depart from a linear ephemeris. We detected an anomaly in the GROND transit light curve which is compatible with a spot on the photosphere of the parent star. The starspot position, size, spot contrast and temperature were established. Using our new and published measurements, we assembled the planet's transmission spectrum over the 370-2350nm wavelength range and its emission spectrum over the 750-8000nm range. By comparing these data to theoretical models we investigated the theoretically predicted variation of the apparent radius of WASP-19b as a function of wavelength and studied the composition and thermal structure of its atmosphere. We conclude that: (i) there is no evidence for strong optical absorbers at low pressure, supporting the common idea that the planet's atmosphere lacks a dayside inversion; (ii) the temperature of the planet is not homogenized, because the high warming of its dayside causes the planet to be more efficient in re-radiating than redistributing energy to the night side; (iii) the planet seems to be outside of any current classification scheme.
We present the discovery of WASP-39b, a highly inflated transiting Saturn-mass planet orbiting a late G-type dwarf star with a period of 4.055259-days, Transit Epoch 2455342.9688+/-0.0002 (HJD), of duration 0.1168d.
We report the discovery of WASP-38b, a long period transiting planet in an eccentric 6.871815 day orbit. The transit epoch is 2455335.92050+/-0.00074 (HJD) and the transit duration is 4.663 hours.
We report the discovery of one super-Earth- (TOI-1749b) and two sub-Neptune-sized planets (TOI-1749c and TOI-1749d) transiting an early M dwarf at a distance of 100pc, which were first identified as planetary candidates using data from the TESS photometric survey. We have followed up this system from the ground by means of multiband transit photometry, adaptive optics imaging, and low-resolution spectroscopy, from which we have validated the planetary nature of the candidates. We find that TOI-1749b, c, and d have orbital periods of 2.39, 4.49, and 9.05days, and radii of 1.4, 2.1, and 2.5R{Earth}, respectively. We also place 95% confidence upper limits on the masses of 57, 14, and 15M{Earth} for TOI-1749b, c, and d, respectively, from transit timing variations. The periods, sizes, and tentative masses of these planets are in line with a scenario in which all three planets initially had a hydrogen envelope on top of a rocky core, and only the envelope of the innermost planet has been stripped away by photoevaporation and/or core-powered mass-loss mechanisms. These planets are similar to other planetary trios found around M dwarfs, such as TOI-175b,c,d and TOI-270b,c,d, in the sense that the outer pair has a period ratio within 1% of 2. Such a characteristic orbital configuration, in which an additional planet is located interior to a near 2:1 period-ratio pair, is relatively rare around FGK dwarfs.
