We report 13 high-precision light curves of eight transits of the exoplanet WASP-52 b, obtained by using four medium-class telescopes, through different filters, and adopting the defocussing technique. One transit was recorded simultaneously from two different observatories and another one from the same site but with two different instruments, including a multi-band camera. Anomalies were clearly detected in five light curves and modelled as star-spots occulted by the planet during the transit events. We fitted the clean light curves with the jktebop code, and those with the anomalies with the prism+gemc codes in order to simultaneously model the photometric parameters of the transits and the position, size and contrast of each star-spot. We used these new light curves and some from the literature to revise the physical properties of the WASP-52 system. Star-spots with similar characteristics were detected in four transits over a period of 43 d. In the hypothesis that we are dealing with the same starspot, periodically occulted by the transiting planet, we estimated the projected orbital obliquity of WASP-52 b to be λ = 3 • .8 ± 8 • .4. We also determined the true orbital obliquity, ψ = 20 • ± 50 • , which is, although very uncertain, the first measurement of ψ purely from star-spot crossings. We finally assembled an optical transmission spectrum of the planet and searched for variations of its radius as a function of wavelength. Our analysis suggests a flat transmission spectrum within the experimental uncertainties.

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Context. The formation and dynamical history of hot Jupiters is currently debated, with wide stellar binaries having been suggested as a potential formation pathway. Additionally, contaminating light from both binary companions and unassociated stars can significantly bias the results of planet characterisation studies, but can be corrected for if the properties of the contaminating star are known. Aim. We search for binary companions to known transiting exoplanet host stars, in order to determine the multiplicity properties of hot Jupiter host stars. We also search for and characterise unassociated stars along the line of sight, allowing photometric and spectroscopic observations of the planetary system to be corrected for contaminating light. Methods. We analyse lucky imaging observations of 97 Southern hemisphere exoplanet host stars, using the Two Colour Instrument on the Danish 1.54 m telescope. For each detected companion star, we determine flux ratios relative to the planet host star in two passbands, and measure the relative position of the companion. The probability of each companion being physically associated was determined using our two-colour photometry. Results. A catalogue of close companion stars is presented, including flux ratios, position measurements, and estimated companion star temperature. For companions that are potential binary companions, we review archival and catalogue data for further evidence. For WASP-77AB and WASP-85AB, we combine our data with historical measurements to determine the binary orbits, showing them to be moderately eccentric and inclined to the line of sight (and hence planetary orbital axis). Combining our survey with the similar Friends of Hot Jupiters survey, we conclude that known hot Jupiter host stars show a deficit of high mass stellar companions compared to the field star population; however, this may be a result of the biases in detection and target selection by ground-based surveys.

We report the detection of a cold Neptune m planet =21±2 M ⊕ orbiting a 0.38 M e M dwarf lying 2.5-3.3 kpc toward the Galactic center as part of a campaign combining ground-based and Spitzer observations to measure the Galactic distribution of planets. This is the first time that the complex real-time protocols described by Yee et al., which aim to maximize planet sensitivity while maintaining sample integrity, have been carried out in practice. Multiple survey and followup teams successfully combined their efforts within the framework of these protocols to detect this planet. This is the second planet in the Spitzer Galactic distribution sample. Both are in the neartomid-disk and are clearly not in the Galactic bulge.

We present nested-grid, high-resolution hydrodynamic simulations of gas and particle dynamics in the vicinity of Mars-to Earth-mass planetary embryos. The simulations extend from the surface of the embryos to a few vertical disk scale heights, with a spatial dynamic range of ∼ 1.4 × 10 5 . Our results confirm that "pebble"-sized particles are readily accreted, with accretion rates continuing to increase up to metre-size "boulders" for a 10% MMSN surface density model. The gas mass flux in and out of the Hill sphere is consistent with the Hill rate, ΣΩR 2 H = 4 10 −3 M ⊕ yr −1 . While smaller size particles mainly track the gas, a net accretion rate of ≈ 2 10 −5 M ⊕ yr −1 is reached for 0.3-1 cm particles, even though a significant fraction leaves the Hill sphere again. Effectively all pebble-sized particles that cross the Bondi sphere are accreted. The resolution of these simulations is sufficient to resolve accretion-driven convection. Convection driven by a nominal accretion rate of 10 −6 M ⊕ yr −1 does not significantly alter the pebble accretion rate. We find that, due to cancellation effects, accretion rates of pebble-sized particles are nearly independent of disk surface density. As a result, we can estimate accurate growth times for specified particle sizes. For 0.3-1 cm size particles, the growth time from a small seed is ∼0.15 million years for an Earth mass planet at 1 AU and ∼0.1 million years for a Mars mass planet at 1.5 AU.dicate that planet formation starts early. What remains to be answered, however, is how planets grow efficiently enough under realistic conditions to agree with the astronomical observations and meteoritic evidence.