Planetas en el universo

Presentamos de forma comparativa las características generales y las propiedades fundamentales de nuestro Sistema Solar, así como las teorías en curso sobre el origen de los planetas y satélites. Los recientes descubrimientos de planetas extrasolares en otras estrellas y las especulaciones sobre la vida en el Universo, son asimismo objeto de análisis en este artículo.Gure eguzki-sistemaren oinarrizko ezaugarriak eta propietate orokorrak modu konparatiboan aurkezten ditugu, eta, honetaz gain, planeten eta sateliteen jatorriari buruzko teoria berrienak ere. Azken aldian beste izarretan aurkitu berri diren planeta extrasolarrak eta Unibertsoko biziari buruzko espekulazioak ere aztertzen dira artikulu honetan.Nous présentons d'une manière comparative les principales caractéristiques et les propriétés fondamentales de notre Sytème Solaire, ainsi que les théories sur l'origine des planètes et satellites. Les récentes découvertes des planètes extrasolaires dans d'autres étoiles et les spéculations sur la vie dans l'Univers sont aussi analysées dans ce travail.We introduce a comparison of the main characteristics and fundamental properties of our Solar System, and the theories on the origin of planets and satellites. The recent discovery of extrasolar planets in other stars and the speculations about life in the Universe are also analysed in this paper

Glory revealed in disk-integrated photometry of Venus

Context. Reflected light from a spatially unresolved planet yields unique insight into the overall optical properties of the planet cover. Glories are optical phenomena caused by light that is backscattered within spherical droplets following a narrow distribution of sizes; they are well known on Earth as localised features above liquid clouds. Aims. Here we report the first evidence for a glory in the disk-integrated photometry of Venus and, in turn, of any planet. Methods. We used previously published phase curves of the planet that were reproduced over the full range of phase angles with model predictions based on a realistic description of the Venus atmosphere. We assumed that the optical properties of the planet as a whole can be described by a uniform and stable cloud cover, an assumption that agrees well with observational evidence. Results. We specifically show that the measured phase curves mimic the scattering properties of the Venus upper-cloud micron-sized aerosols, also at the small phase angles at which the glory occurs, and that the glory contrast is consistent with what is expected after multiple scattering of photons. In the optical, the planet appears to be brighter at phase angles of 11-13 deg than at full illumination; it undergoes a maximum dimming of up to 10 percent at phases in between. Conclusions. Glories might potentially indicate spherical droplets and, thus, extant liquid clouds in the atmospheres of exoplanets. A prospective detection will require exquisite photometry at the small planet-star separations of the glory phase angles.Comment: In press. Astronomy & Astrophysics. Letter to the Editor; 201

The Impact of Hot Jupiters on the Spin-down of their Host Stars

We present a numerical Magnetohydrodynamic (MHD) study of the dependence of stellar mass and angular momentum- loss rates on the orbital distance to close-in giant planets. We find that the mass loss rate drops by a factor of $\approx$1.5-2, while the angular momentum loss rate drops by a factor of $\approx$4 as the distance decreases past the Alfv\'en surface. This reduction in angular momentum loss is due to the interaction between the stellar and planetary Alfv\'en surfaces, which modifies the global structure of the stellar corona and stellar wind on the hemisphere facing the planet, as well as the opposite hemisphere. The simulation also shows that the magnitude of change in angular momentum loss rate depends mostly on the strength of the planetary magnetic field and not on its polarity. The interaction however, begins at greater separation if the overall field topology of the star and the planet are of anti-aligned. Our results are consistent with evidence for excess angular momentum in stars harboring close-in giant planets, and show that the reduction in wind-driven angular momentum loss can compete with, and perhaps dominate, spin-up due to tidal interaction.Comment: 6 pages, 3 figure

Temporal and spatial variations of the absolute reflectivity of Jupiter and Saturn from 0.38 to 1.7 μ\mum with PlanetCam-UPV/EHU

We provide measurements of the absolute reflectivity of Jupiter and Saturn along their central meridians in filters covering a wide range of visible and near-infrared wavelengths (from 0.38 to 1.7 $\mu$m) that are not often presented in the literature. We also give measurements of the geometric albedo of both planets and discuss the limb-darkening behavior and temporal variability of their reflectivity values for a period of four years (2012-2016). This work is based on observations with the PlanetCam-UPV/EHU instrument at the 1.23 m and 2.2 m telescopes in Calar Alto Observatory (Spain). The instrument simultaneously observes in two channels: visible (VIS; 0.38-1.0 $\mu$m) and short-wave infrared (SWIR; 1.0--1.7 $\mu$m). We obtained high-resolution observations via the lucky-imaging method. We show that our calibration is consistent with previous independent determinations of reflectivity values of these planets and, for future reference, provide new data extended in the wavelength range and in the time. Our results have an uncertainty in absolute calibration of 10--20\%. We show that under the hypothesis of constant geometric albedo, we are able to detect absolute reflectivity changes related to planetary temporal evolution of about 5-10\%.Comment: 13 pages, 18 figures, (in press

Hazes and clouds in a singular triple vortex in Saturn's atmosphere from HST/WFC3 multispectral imaging

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Multilayer hazes over Saturn’s hexagon from Cassini ISS limb images

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Gamified Digital Game-Based Learning as a Pedagogical Strategy: Student Academic Performance and Motivation

Digital game-based learning (DGBL) and Gamification are emerging methodological strategies in education. This research aims to analyze the effects on academic performance and motivation after an experience combining DGBL and Gamification in university students. The sample comprises 126 students, of whom 38 were in the experimental group. Three measurement instruments have been used: an evaluative test to measure academic performance, the Questionnaire on Motivation for Cooperative Playful Learning Strategies (CMELAC) and a questionnaire with three open-ended questions, which complement the measurement of motivation. This analysis is conducted using independent sample t-tests. We undertook a Bonferroni adjustment to the alpha level (new p = 0.017). The results show significant differences in academic performance between the control and experimental groups. Motivation shows high values among all participants. No significant differences were found between the two experimental subgroups when the competition was added to the dynamics. In conclusion, the results of the present study support the gamified DGBL method as an exciting teaching tool that corresponds to students’ active learning and provide valuable immediate feedback on students’ attempts, improvements in academic performance and a high level of motivation

Limb imaging of the Venus O2 visible nightglow with the Venus Monitoring Camera

We investigated the Venus O2 visible nightglow with imagery from the Venus Monitoring Camera on Venus Express. Drawing from data collected between April 2007 and January 2011, we study the global distribution of this emission, discovered in the late 70s by the Venera 9 and 10 missions. The inferred limb-viewing intensities are on the order of 150 kiloRayleighs at the lower latitudes and seem to drop somewhat towards the poles. The emission is generally stable, although there are episodes when the intensities rise up to 500 kR. We compare a set of Venus Monitoring Camera observations with coincident measurements of the O2 nightglow at 1.27 {\mu}m made with the Visible and Infrared Thermal Imaging Spectrometer, also on Venus Express. From the evidence gathered in this and past works, we suggest a direct correlation between the instantaneous emissions from the two O2 nightglow systems. Possible implications regarding the uncertain origin of the atomic oxygen green line at 557.7 nm are noted.Comment: 7 pages, 3 figure