[en] Despite the existence of many short-period hot Jupiters, there is not one hot Neptune with an orbital period less than 2.5 days. Here, we discuss a cluster analysis of the currently known 106 transiting exoplanets to investigate a possible explanation for this observation. We find two distinct clusters in the mass-density space, one with hot Jupiters with a wide range of orbital periods (0.8-114 days) and a narrow range of planet radii (1.2 ± 0.2 R_J ) and another one with a mixture of super-Earths, hot Neptunes, and hot Jupiters, exhibiting a surprisingly narrow period distribution (3.7 ± 0.8 days). These two clusters follow strikingly different distributions in the period-radius parameter plane. The branch of sub-Jupiter mass exoplanets is censored by the orbital period at the large-radius end: no planets with mass between 0.02 and 0.8 M_J or with radius between 0.25 and 1.0 R_J are known with P_orb < 2.5 days. This clustering is not predicted by current theories of planet formation and evolution, which we also review briefly.

[en] We investigate the formation of double-peaked asymmetric line profiles of CO in the fundamental band spectra emitted by young (1-5 Myr) protoplanetary disks hosted by a 0.5-2 M _☉ star. Distortions of the line profiles can be caused by the gravitational perturbation of an embedded giant planet with q = 4.7 × 10^–3 stellar-to-planet mass ratio. Locally isothermal, two-dimensional hydrodynamic simulations show that the disk becomes globally eccentric inside the planetary orbit with stationary ∼0.2-0.25 average eccentricity after ∼2000 orbital periods. For orbital distances 1-10 AU, the disk eccentricity is peaked inside the region where the fundamental band of CO is thermally excited. Hence, these lines become sensitive indicators of the embedded planet via their asymmetries (both in flux and wavelength). We find that the line shape distortions (e.g., distance, central dip, asymmetry, and positions of peaks) of a given transition depend on the excitation energy (i.e., on the rotational quantum number J). The magnitude of line asymmetry is increasing/decreasing with J if the planet orbits inside/outside the CO excitation zone (R _CO ≤ 3, 5, and 7 AU for a 0.5, 1, and 2 M _☉ star, respectively), thus one can constrain the orbital distance of a giant planet by determining the slope of the peak asymmetry-J profile. We conclude that the presented spectroscopic phenomenon can be used to test the predictions of planet formation theories by pushing the age limits for detecting the youngest planetary systems

[en] KOI-13.01, a planet-sized companion in an optical double star, was announced as one of the 1235 Kepler planet candidates in 2011 February. The transit curves show significant distortion that was stable over the ∼130 days time span of the data. Here we investigate the phenomenon via detailed analyses of the two components of the double star and a re-reduction of the Kepler data with pixel-level photometry. Our results indicate that KOI-13 is a common proper motion binary, with two rapidly rotating components (vsin i ∼ 65-70 km s^-1). We identify the host star of KOI-13.01 and conclude that the transit curve asymmetry is consistent with a companion orbiting a rapidly rotating, possibly elongated star on an oblique orbit. The radius of the transiter is 2.2 R_J , implying an irradiated late-type dwarf, probably a hot brown dwarf rather than a planet. KOI-13 is the first example for detecting orbital obliquity for a substellar companion without measuring the Rossiter-McLaughlin effect with spectroscopy.

[en] Unlike NASA’s original Kepler Discovery Mission, the renewed K2 Mission will target the plane of the Ecliptic, observing each field for approximately 75 days. This will bring new opportunities and challenges, in particular the presence of a large number of main-belt asteroids that will contaminate the photometry. The large pixel size makes K2 data susceptible to the effects of apparent minor planet encounters. Here, we investigate the effects of asteroid encounters on photometric precision using a subsample of the K2 engineering data taken in 2014 February. We show examples of asteroid contamination to facilitate their recognition and distinguish these events from other error sources. We conclude that main-belt asteroids will have considerable effects on K2 photometry of a large number of photometric targets during the Mission that will have to be taken into account. These results will be readily applicable for future space photometric missions applying large-format CCDs, such as TESS and PLATO

[en] In this paper, we present visible-range light curves of the irregular Uranian satellites Sycorax, Caliban, Prospero, Ferdinand, and Setebos taken with the Kepler Space Telescope over the course of the K2 mission. Thermal emission measurements obtained with the Herschel /PACS and Spitzer /MIPS instruments of Sycorax and Caliban were also analyzed and used to determine size, albedo, and surface characteristics of these bodies. We compare these properties with the rotational and surface characteristics of irregular satellites in other giant planet systems and also with those of main belt and Trojan asteroids and trans-Neptunian objects. Our results indicate that the Uranian irregular satellite system likely went through a more intense collisional evolution than the irregular satellites of Jupiter and Saturn. Surface characteristics of Uranian irregular satellites seem to resemble the Centaurs and trans-Neptunian objects more than irregular satellites around other giant planets, suggesting the existence of a compositional discontinuity in the young solar system inside the orbit of Uranus.

[en] Remote investigations of ancient matter in the solar system have traditionally been carried out through observations of long-period (LP) comets, which are less affected by solar irradiation than their short-period counterparts orbiting much closer to the Sun. Here we summarize the results of our decade-long survey of the distant activity of LP comets. We found that the most important separation in the data set is based on the dynamical nature of the objects. Dynamically new comets are characterized by a higher level of activity on average: the most active new comets in our sample can be characterized by Afρ values >3–4, higher than those for our most active returning comets. New comets develop more symmetric comae, suggesting a generally isotropic outflow. In contrast to this, the comae of recurrent comets can be less symmetrical, ocassionally exhibiting negative slope parameters, which suggest sudden variations in matter production. The morphological appearance of the observed comets is rather diverse. A surprisingly large fraction of the comets have long, tenuous tails, but the presence of impressive tails does not show a clear correlation with the brightness of the comets.

[en] We report the discovery of a new totally eclipsing binary (R.A. = ${06}^{\mathrm{h}}{40}^{\mathrm{m}}{29}^{\mathrm{s}}11$; decl. = +38°56′52″2; J = 2000.0; R_max = 17.2 mag) with an sdO primary and a strongly irradiated red dwarf companion. It has an orbital period of P_orb = 0.187284394(11) day and an optical eclipse depth in excess of 5 mag. We obtained 2 low-resolution classification spectra with GTC/OSIRIS and 10 medium-resolution spectra with WHT/ISIS to constrain the properties of the binary members. The spectra are dominated by H Balmer and He ii absorption lines from the sdO star, and phase-dependent emission lines from the irradiated companion. A combined spectroscopic and light curve analysis implies a hot subdwarf temperature of T_eff(spec) = 55,000 ± 3000 K, surface gravity of log g (phot) = 6.2 ± 0.04 (cgs), and a He abundance of $\mathrm{l}\mathrm{o}\mathrm{g}(n\mathrm{H}\mathrm{e}/n\mathrm{H})=-<!--\; ???\; -->2.24\pm <!--\; ??\; -->0.40$. The hot sdO star irradiates the red dwarf companion, heating its substellar point to about 22,500 K. Surface parameters for the companion are difficult to constrain from the currently available data: the most remarkable features are the strong H Balmer and C ii-iii lines in emission. Radial velocity estimates are consistent with the sdO+dM classification. The photometric data do not show any indication of sdO pulsations with amplitudes greater than 7 mmag, and Hα-filter images do not provide evidence for the presence of a planetary nebula associated with the sdO star.

[en] We report the discovery of HAT-P-27b, an exoplanet transiting the moderately bright G8 dwarf star GSC 0333-00351 (V = 12.214). The orbital period is 3.039586 ± 0.000012 days, the reference epoch of transit is 2455186.01879 ± 0.00054 (BJD), and the transit duration is 0.0705 ± 0.0019 days. The host star with its effective temperature 5300 ± 90 K is somewhat cooler than the Sun and is more metal-rich with a metallicity of +0.29 ± 0.10. Its mass is 0.94 ± 0.04 M_sun and radius is 0.90^+0.05_-0.04 R_sun. For the planetary companion we determine a mass of 0.660 ± 0.033 M_J and radius of 1.038^+0.077_-0.058 R_J. For the 30 known transiting exoplanets between 0.3 M_J and 0.8 M_J, a negative correlation between host star metallicity and planetary radius and an additional dependence of planetary radius on equilibrium temperature are confirmed at a high level of statistical significance.

[en] We report the discovery of HAT-P-31b, a transiting exoplanet orbiting the V = 11.660 dwarf star GSC 2099-00908. HAT-P-31b is the first planet discovered with the Hungarian-made Automated Telescope (HAT) without any follow-up photometry, demonstrating the feasibility of a new mode of operation for the HATNet project. The 2.17 M_J , 1.1 R_J planet has a period of P_b = 5.0054 days and maintains an unusually high eccentricity of e_b = 0.2450 ± 0.0045, determined through Keck, FIbr-fed Echelle Spectrograph, and Subaru high-precision radial velocities (RVs). Detailed modeling of the RVs indicates an additional quadratic residual trend in the data detected to very high confidence. We interpret this trend as a long-period outer companion, HAT-P-31c, of minimum mass 3.4 M_J and period ≥2.8 years. Since current RVs span less than half an orbital period, we are unable to determine the properties of HAT-P-31c to high confidence. However, dynamical simulations of two possible configurations show that orbital stability is to be expected. Further, if HAT-P-31c has non-zero eccentricity, our simulations show that the eccentricity of HAT-P-31b is actively driven by the presence of c, making HAT-P-31 a potentially intriguing dynamical laboratory.

[en] Although photometric and spectroscopic surveys with the Spitzer Space Telescope remarkably increased the number of well-studied debris disks around A-type and Sun-like stars, detailed analyses of debris disks around F-type stars remained less frequent. Using the MIPS camera and the Infrared Spectrograph (IRS) spectrograph, we searched for debris dust around 82 F-type stars with Spitzer. We found 27 stars that harbor debris disks, nine of which are new discoveries. The dust distribution around two of our stars, HD 50571 and HD 170773, was found to be marginally extended on the 70 μm MIPS images. Combining the MIPS and IRS measurements with additional infrared and submillimeter data, we achieved excellent spectral coverage for most of our debris systems. We have modeled the excess emission of 22 debris disks using a single temperature dust ring model and of five debris systems with two-temperature models. The latter systems may contain two dust rings around the star. In accordance with the expected trends, the fractional luminosity of the disks declines with time, exhibiting a decay rate consistent with the range of model predictions. We found the distribution of radial dust distances as a function of age to be consistent with the predictions of both the self-stirred and the planetary-stirred disk evolution models. A more comprehensive investigation of the evolution of debris disks around F-type stars, partly based on the presented data set, will be the subject of an upcoming paper.