361 research outputs found
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
1.5-2, while the angular momentum loss rate drops by a factor of
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 m 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 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 m) and short-wave infrared (SWIR; 1.0--1.7 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
Ver abstrac
Multilayer hazes over Saturn’s hexagon from Cassini ISS limb images
Producción CientíficaVer abstract
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
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