190 research outputs found
Jupiter as an exoplanet: UV to NIR transmission spectrum reveals hazes, a Na layer and possibly stratospheric H2O-ice clouds
Currently, the analysis of transmission spectra is the most successful
technique to probe the chemical composition of exoplanet atmospheres. But the
accuracy of these measurements is constrained by observational limitations and
the diversity of possible atmospheric compositions. Here we show the UV-VIS-IR
transmission spectrum of Jupiter, as if it were a transiting exoplanet,
obtained by observing one of its satellites, Ganymede, while passing through
Jupiter's shadow i.e., during a solar eclipse from Ganymede. The spectrum shows
strong extinction due to the presence of clouds (aerosols) and haze in the
atmosphere, and strong absorption features from CH4. More interestingly, the
comparison with radiative transfer models reveals a spectral signature, which
we attribute here to a Jupiter stratospheric layer of crystalline H2O ice. The
atomic transitions of Na are also present. These results are relevant for the
modeling and interpretation of giant transiting exoplanets. They also open a
new technique to explore the atmospheric composition of the upper layers of
Jupiter's atmosphere.Comment: Accepted for publication in ApJ Letter
Fear of Falling in Older Adults Treated at a Geriatric Day Hospital: Results from a Cross-Sectional Study
(1) Background: The fear of falling (FOF) is a geriatric syndrome that causes a decrease in daily activities and personal autonomy. Its prevalence is highly variable as are the methodologies used to assess it. This study aimed at estimating the prevalence and describing the main determinants of FOF in older adults attending a geriatric day hospital. (2) Methods: Descriptive, cross-sectional study of individuals aged >= 70 years, who attended an ambulatory functional rehabilitation group in the metropolitan area of Barcelona. FOF was assessed using the Activities-Specific Balance Confidence (ABC) scale. Other recorded outcomes were: sex, age, marital status, living alone, level of education, degree of autonomy, pain, previous falls, visual acuity, and signs of depression. Prevalence was estimated overall and according to the possible determinants. (3) Results: The study included 62 individuals (66.1% women), with a prevalence of fear of falling of 38.7% (95% CI 26.2-51.2%). The identified determinants were pain (OR = 7.4, 95% CI 1.4-39.7), a history of falls (OR = 25.3, 95% CI 2.1-303.4), poor visual acuity (OR = 5.6, 95% CI 1.0-29.8), and signs of depression (OR = 19.3, 95% CI 1.4-264.3). (4) Conclusions: The prevalence and determinants of fear of falling in older adults attending geriatric day hospitals were similar to those described in those dwelling in the community
Novena y vida del glorioso peregrino San Amaro
Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Contiene: Novena al peregrino San Amaro / escrita por D. E. Melendo. Vida del peregrino San Amaro / según la escribió el P. M. Flórez en su obra España sagrada, tomo XXVI
A complex storm system in Saturn’s north polar atmosphere in 2018
Producción CientíficaSaturn’s convective storms usually fall in two categories. One consists of mid-sized storms ∼2,000 km wide, appearing as irregular bright cloud systems that evolve rapidly, on scales of a few days. The other includes the Great White Spots, planetary-scale giant storms ten times larger than the mid-sized ones, which disturb a full latitude band, enduring several months, and have been observed only seven times since 1876. Here we report a new intermediate type, observed in 2018 in the north polar region. Four large storms with east–west lengths ∼4,000–8,000 km (the first one lasting longer than 200 days) formed sequentially in close latitudes, experiencing mutual encounters and leading to zonal disturbances affecting a full latitude band ∼8,000 km wide, during at least eight months. Dynamical simulations indicate that each storm required energies around ten times larger than mid-sized storms but ∼100 times smaller than those necessary for a Great White Spot. This event occurred at about the same latitude and season as the Great White Spot in 1960, in close correspondence with the cycle of approximately 60 years hypothesized for equatorial Great White Spots.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AYA2015-65041-P)Gobierno Vasco (project IT-366-19
Radio Observations of HD 80606 Near Planetary Periastron
This paper reports Very Large Array observations at 325 and 1425 MHz (90cm
and 20cm) during and near the periastron passage of HD 80606b on 2007 November
20. We obtain flux density limits (3-sigma) of 1.7 mJy and 48 microJy at 325
and 1425 MHz, respectively, equivalent to planetary luminosity limits of 2.3 x
10^{24} erg/s and 2.7 x 10^{23} erg/s. These are well above the Jovian value
(at 40 MHz) of 2 x 10^{18} erg/s. The motivation for these observations was
that the planetary magnetospheric emission is driven by a stellar
wind-planetary magnetosphere interaction so that the planetary luminosity would
be elevated. Near periastron, HD 80606b might be as much as 3000 times more
luminous than Jupiter. Recent transit observations of HD 80606b provide
stringent constraints on the planetary mass and radius, and, because of the
planet's highly eccentric orbit, its rotation period is likely to be
"pseudo-synchronized" to its orbital period, allowing a robust estimate of the
former. We are able to make robust estimates of the emission frequency of the
planetary magnetospheric emission and find it to be around 60--90 MHz. We
compare HD 80606b to other high-eccentricity systems and assess the detection
possibilities for both near-term and more distant future systems. Of the known
high eccentricity planets, only HD 80606b is likely to be detectable, as HD
20782B b and HD 4113b are both likely to have weaker magnetic field strengths.
Both the forthcoming "EVLA low band" system and the Low Frequency Array may be
able to improve upon our limits for HD 80606b, and do so at a more optimum
frequency. If the low-frequency component of the Square Kilometre Array
(SKA-lo) and a future lunar radio array are able to approach their thermal
noise limits, they should be able to detect an HD 80606b-like planet, unless
the planet's luminosity increases by substantially less than a factor of 3000.Comment: 9 pages; accepted for publication in A
Detection of a transit by the planetary companion of HD 80606
We report the detection of a transit egress by the ~ 3.9-Jupiter-mass planet
HD 80606b, an object in a highly-eccentric orbit (e ~ 0.93) about its parent
star of approximately solar type. The astrophysical reality of the signal of
variability in HD 80606 is confirmed by observation with two independent
telescope systems, and checks against several reference stars in the field.
Differential photometry with respect to the nearby comparison star HD 80607
provides a precise light curve. Modelling of the light curve with a full
eccentric-orbit model indicates a planet/star-radius ratio of 0.1057 +/-
0.0018, corresponding to a planet radius of 1.029 R_J for a solar-radius parent
star; and a precise orbital inclination of 89.285 +/- 0.023 degrees, giving a
total transit duration of 12.1 +/- 0.4 hours. The planet hence joins HD 17156b
in a class of highly eccentric transiting planets, in which HD 80606b has both
the longest period and most eccentric orbit. The recently reported discovery of
a secondary eclipse of HD 80606b by the Spitzer Space Observatory permits a
combined analysis with the mid-time of primary transit in which the orbital
parameters of the system can be tightly constrained. We derive a transit
ephemeris of T_tr = HJD (2454876.344 +/- 0.011) + (111.4277 +/- 0.0032) E.Comment: Accepted for publication in MNRAS Letter
The impact of a large object with Jupiter in July 2009
On 2009 July 19, we observed a single, large impact on Jupiter at a
planetocentric latitude of 55^{\circ}S. This and the Shoemaker-Levy 9 (SL9)
impacts on Jupiter in 1994 are the only planetary-scale impacts ever observed.
The 2009 impact had an entry trajectory opposite and with a lower incidence
angle than that of SL9. Comparison of the initial aerosol cloud debris
properties, spanning 4,800 km east-west and 2,500 km north-south, with those
produced by the SL9 fragments, and dynamical calculations of pre-impact orbit,
indicate that the impactor was most probably an icy body with a size of 0.5-1
km. The collision rate of events of this magnitude may be five to ten times
more frequent than previously thought. The search for unpredicted impacts, such
as the current one, could be best performed in 890-nm and K (2.03-2.36 {\mu}m)
filters in strong gaseous absorption, where the high-altitude aerosols are more
reflective than Jupiter's primary cloud.Comment: 15 pages, 5 figure
The EBLM project. II. A very hot, low-mass M dwarf in an eccentric and long period eclipsing binary system from SuperWASP
In this paper, we derive the fundamental properties of
1SWASPJ011351.29+314909.7 (J0113+31), a metal-poor (-0.40 +/- 0.04 dex),
eclipsing binary in an eccentric orbit (~0.3) with an orbital period of ~14.277
d. Eclipsing M dwarfs orbiting solar-type stars (EBLMs), like J0113+31, have
been identified from WASP light curves and follow-up spectroscopy in the course
of the transiting planet search. We present the first binary of the EBLM sample
to be fully analysed, and thus, define here the methodology. The primary
component with a mass of 0.945 +/- 0.045 Msun has a large radius (1.378 +/-
0.058 Rsun) indicating that the system is quite old, ~9.5 Gyr. The M-dwarf
secondary mass of 0.186 +/- 0.010 Msun and radius of 0.209 +/- 0.011 Rsun are
fully consistent with stellar evolutionary models. However, from the
near-infrared secondary eclipse light curve, the M dwarf is found to have an
effective temperature of 3922 +/- 42 K, which is ~600 K hotter than predicted
by theoretical models. We discuss different scenarios to explain this
temperature discrepancy. The case of J0113+31 for which we can measure mass,
radius, temperature and metallicity, highlights the importance of deriving
mass, radius and temperature as a function of metallicity for M dwarfs to
better understand the lowest mass stars. The EBLM Project will define the
relationship between mass, radius, temperature and metallicity for M dwarfs
providing important empirical constraints at the bottom of the main sequence.Comment: 13 pages, 7 figures. Accepted for publication in A&
An ingress and a complete transit of HD 80606 b
We have used four telescopes at different longitudes to obtain
near-continuous lightcurve coverage of the star HD 80606 as it was transited by
its \sim 4-MJup planet. The observations were performed during the predicted
transit windows around the 25th of October 2008 and the 14th of February 2009.
Our data set is unique in that it simultaneously constrains the duration of the
transit and the planet's period. Our Markov-Chain Monte Carlo analysis of the
light curves, combined with constraints from radial-velocity data, yields
system parameters consistent with previously reported values. We find a
planet-to-star radius ratio marginally smaller than previously reported,
corresponding to a planet radius of Rp = 0.921 \pm 0.036RJup .Comment: 6 pages, 2 figures, MNRAS accepte
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