310 research outputs found
Variability in low Mars atmosphere's HO concentration stimulated by solar cycle activity
Mars' thin, CO-rich atmosphere poses a unique puzzle involving
composition, climate history, and habitability. This work explores the
intrincate relationship between Mars' atmospheric variations and dynamic solar
activity patterns. We focus on periodic oscillations in HO vapor and the
Pectinton solar flux index in the = 10.7 cm radio band, around the
characteristic 11-year solar cycle. Periodic Mars activity was studied using
data from Mars Express' SPICAM instrument spanning 2004-2018. The Lomb-Scargle
Periodogram method was applied to analyze the power spectra of both signals
around this period, calibrated using peaks associated with the seasonal Martian
cycle. This method was validated by analyzing power spectra of chemical species
abundances in Earth's atmosphere, obtained from the NRLMSISE 00 empirical model
provided by the National Oceanic and Atmospheric Administration (NOAA). Model
executions reproduced chemical abundance data for various atmospheric species
(N, O, N, H, Ar, and He) at two reference heights (upper mesosphere
and low ionosphere) over a 1961-2021 time span. Results suggest a connection
between variability in HO vapor concentration in Mars' atmosphere and
fluctuations in the Pectinton solar flux index. We propose the Lomb-Scargle
Periodogram method as a heuristic for studying oscillatory activity in
planetary atmospheres with non-uniformly sampled data. While our results
provide valuable insights, further analysis, cross-referencing with data from
different orbiters, is required to deepen our understanding of these findings
in the fields of planetary climatology and atmospheric physics.Comment: 25 pages, 24 figures. Submitted to MNRA
Location, orbit and energy of a meteoroid impacting the moon during the Lunar Eclipse of January 21, 2019
During lunar eclipse of January 21, 2019 a meteoroid impacted the Moon
producing a visible light flash. The impact was witnessed by casual observers
offering an opportunity to study the phenomenon from multiple geographical
locations. We use images and videos collected by observers in 7 countries to
estimate the location, impact parameters (speed and incoming direction) and
energy of the meteoroid. Using parallax, we achieve determining the impact
location at lat. , lon. and
geocentric distance as 356553 km. After devising and applying a photo-metric
procedure for measuring flash standard magnitudes in multiple RGB images having
different exposure times, we found that the flash, had an average G-magnitude
. We use gravitational ray tracing (GRT) to
estimate the orbital properties and likely radiant of the impactor. We find
that the meteoroid impacted the moon with a speed of km/s (70%
C.L.) and at a shallow angle, degrees. Assuming a normal error
for our estimated flash brightness, educated priors for the luminous efficiency
and object density, and using the GRT-computed probability distributions of
impact speed and incoming directions, we calculate posterior probability
distributions for the kinetic energy (median = 0.8 kton), body
mass ( = 27 kg) and diameter ( = 29 cm), and crater
size ( = 9 m). If our assumptions are correct, the crater left by
the impact could be detectable by prospecting lunar probes. These results arose
from a timely collaboration between professional and amateur astronomers which
highlight the potential importance of citizen science in astronomy.Comment: 19 pages, 11 figures, 4 tables. Data and scripts available in
https://github.com/seap-udea/MoonFlashes. Accepted for publication in MNRA
Chirping compact stars: gravitational radiation and detection degeneracy with binary systems A conceptual pathfinder for space-based gravitational-wave observatories
Compressible, Riemann S-type ellipsoids can emit gravitational waves (GWs)
with a chirp-like behavior (hereafter chirping ellipsoids, CELs). We show that
the GW frequency-amplitude evolution of CELs (mass ~M, radius
~km, polytropic equation of state with index ) is
indistinguishable from that emitted by double white dwarfs (DWDs) and by
extreme mass-ratio inspirals (EMRIs) composed of an intermediate-mass
(e.g.~) black hole and a planet-like (e.g.~)
companion, in a specific frequency interval within the detector sensitivity
band in which the GWs of all these systems are quasi-monochromatic. We estimate
that for reasonable astrophysical assumptions, the rates in the local Universe
of CELs, DWDs and EMRIs in the mass range considered here, are very similar,
posing a detection-degeneracy challenge for space-based GW detectors. The
astrophysical implications of this CEL-binary detection degeneracy by
space-based GW-detection facilities, are outlined.Comment: Submitted to Phys. Rev.
The Spin-Orbit Evolution of GJ 667C System: The Effect of Composition and Other Planet’s Perturbations
Potentially habitable planets within the habitable zone of M dwarfs are affected by tidal interaction. We studied tidal evolution in GJ 667C using a numerical code we call TIDEV. We reviewed the problem of dynamical evolution, focusing on the effects of a rheological treatment, different compositions and the inclusion of orbital perturbations on the spin-down time and the probability of becoming trapped in a low spin-orbit resonance. The composition has a noticeable effect on the spin-down time, which changes, in some cases, by almost a factor of 2 with respect to the value estimated for a reference Earth-like model. We calculated the time required to reach a low resonance value (3:2) for a configuration of six planets. Capture probabilities are affected when assuming different compositions and eccentricity variations. We chose planets b and c to evaluate the probabilities of capture in resonances below 5:2 for two compositions: Earth-like and Waterworld planets. We found that perturbations, although having a secular effect on eccentricities, have a low impact on capture probabilities and no effect on spin-down times. The implications of the eccentricity variations and actual habitability of the GJ 667C system are discussed.Facultad de Ciencias Astronómicas y Geofísica
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Coupling between annual and ENSO timescales in the malaria-climate association in Colombia.
We present evidence that the El Niño phenomenon intensifies the annual cycle of malaria cases for Plasmodium vivax and Plasmodium falciparum in endemic areas of Colombia as a consequence of concomitant anomalies in the normal annual cycle of temperature and precipitation. We used simultaneous analyses of both variables at both timescales, as well as correlation and power spectral analyses of detailed spatial (municipal) and temporal (monthly) records. During "normal years," endemic malaria in rural Colombia exhibits a clear-cut "normal" annual cycle, which is tightly associated with prevalent climatic conditions, mainly mean temperature, precipitation, dew point, and river discharges. During historical El Niño events (interannual time scale), the timing of malaria outbreaks does not change from the annual cycle, but the number of cases intensifies. Such anomalies are associated with a consistent pattern of hydrological and climatic anomalies: increase in mean temperature, decrease in precipitation, increase in dew point, and decrease in river discharges, all of which favor malaria transmission. Such coupling explains why the effect appears stronger and more persistent during the second half of El Niño's year (0), and during the first half of the year (+1). We illustrate this finding with data for diverse localities in Buenaventura (on the Pacific coast) and Caucasia (along the Cauca river floodplain), but conclusions have been found valid for multiple localities throughout endemic regions of Colombia. The identified coupling between annual and interannual timescales in the climate-malaria system shed new light toward understanding the exact linkages between environmental, entomological, and epidemiological factors conductive to malaria outbreaks, and also imposes the coupling of those timescales in public health intervention programs
`Oumuamua as a messenger from the Local Association
7 pages, one table, two figures, accepted for publication by ApJL. © 2018. The American Astronomical Society. All rights reserved.With a hyperbolic trajectory around the Sun, 'Oumuamua is the first confirmed interstellar object. However, its origin is poorly known. By simulating the orbits of 0.23 million local stars, we find 109 encounters with periastron less than 5 pc. 'Oumuamua's low peculiar velocity is suggestive of its origin from a young stellar association with similar velocity. In particular, we find that 'Oumuamua would have had slow encounters with at least five young stars belonging to the Local Association, thus suggesting these as plausible sites for formation and ejection. In addition to an extremely elongated shape, the available observational data for 'Oumuamua indicates a red color, suggestive of a potentially organic-rich and activity-free surface. These characteristics seem consistent with formation through energetic collisions between planets and debris objects in the middle part of a young stellar system. We estimate an abundance of at least 6.0 × 10 -3 au -3 for such interstellar objects with mean diameter larger than 100 m and find that it is likely that most of them will be ejected into the Galactic halo. Our Bayesian analysis of the available light curves indicates a rotation period of 6.96 +1.45 -0.39, which is consistent with the estimation by Meech et al. and shorter than those in other literature. The codes and results are available on GitHub (https://github.com/phillippro/Oumuamua).Peer reviewe
SU(4)_L X U(1)_X three-family model for the electroweak interaction
An extension of the gauge group of the standard model
to the symmetry group (3-4-1 for short) is presented.
The model does not contain exotic electric charges and anomaly cancellation is
achieved with a family of quarks transforming differently from the other two,
thus leading to FCNC. By introducing a discrete symmetry we obtain a
consistent fermion mass spectrum, and avoid unitarity violation of the CKM
mixing matrix arising from the mixing of ordinary and exotic quarks. The
neutral currents coupled to all neutral vector bosons are studied, and by using
CERN LEP and SLAC Linear Collider data at Z-pole and atomic parity violation
data, we bound parameters of the model related to tree-level
mixing. These parameters are further constrained by using experimental input
from neutral meson mixing in the analysis of sources of FCNC present in the
model. Constraints coming from the contribution of exotic particles to the
one-loop oblique electroweak parameters , and are also briefly
discussed. Finally, a comparison is done of the predictions of different
classes of 3-4-1 models without exotic electric charges.Comment: 26 pages, 6 tables, 1 figure. Accepted for publication in Phys. Rev.
Pulsar acceleration by asymmetric emission of sterile neutrinos
A convincing explanation for the observed pulsar large peculiar velocities is
still missing. We argue that any viable particle physics solution would most
likely involve the resonant production of a non-interacting neutrino of
mass --50 keV. We propose a model where anisotropic magnetic
field configurations strongly bias the resonant spin flavour precession of tau
antineutrinos into . For internal magnetic fields B_{int} \gsim
10^{15} G a - transition magnetic moment of the order of
Bohr magnetons is required. The asymmetric emission of from
the core can produce sizeable natal kicks and account for recoil velocities of
several hundred kilometers per second.Comment: 14 pages, AASTEX, 2 figures (uses epsfig). Minor typos corrected.
Added acknowledgments to the funding institutes BID and Colciencia
Power Quality Indices Estimation Platform
En este artículo se presenta una plataforma interactiva para la estimación de índices de calidad de la potencia de sistemas eléctricos monofásicos, en conformidad con el estándar IEEE 1459-2010. La plataforma PQanalizador se desarrolló con el objetivo de apoyar actividades de docencia e investigación en calidad de la energía eléctrica. La plataforma estima los índices a partir de señales de voltaje y corriente usando tres diferentes algoritmos basados en la transformada rápida de Fourier (FFT), la transformada Wavelet Packet (WPT) y la metodología de mínimos cuadrados. Los resultados muestran que los algoritmos implementados son eficientes para la estimación de los índices de calidad de la potencia y que la plataforma puede ser usada según los objetivos propuestos.An interactive platform for estimating the quality indices in single phase electric power systems is presented. It meets the IEEE 1459-2010 standard recommendations. The platform was developed in order to support teaching and research activities in electric power quality. The platform estimates the power quality indices from voltage and current signals using three different algorithms based on fast Fourier transform (FFT), wavelet packet transform (WPT) and least squares method. The results show that the algorithms implemented are efficient for estimating the quality indices of the power and the platform can be used according to the objectives established.
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