17 research outputs found
Tidal Forcing on the Sun and the 11-year Solar Activity Cycle
The hypothesis that tidal forces on the Sun are related to the modulations of
the solar-activity cycle has gained increasing attention. The works proposing
physical mechanisms of planetary action via tidal forcing have in common that
quasi-alignments between Venus, Earth, and Jupiter (V-E-J configurations) would
provide a basic periodicity of years able to synchronize the
operation of solar dynamo with these planetary configurations. Nevertheless,
the evidence behind this particular tidal forcing is still controversial. In
this context we develop, for the first time, the complete Sun's tide-generating
potential (STGP) in terms of a harmonic series, where the effects of different
planets on the STGP are clearly separated and identified. We use a modification
of the spectral analysis method devised by Kudryavtsev (J. Geodesy. 77, 829,
2004; Astron. Astrophys. 471, 1069, 2007b) that permits to expand any function
of planetary coordinates to a harmonic series over long time intervals. We
build a catalog of 713 harmonic terms able to represent the STGP with a high
degree of precision. We look for tidal forcings related to V-E-J configurations
and specifically the existence of periodicities around years.
Although the obtained tidal periods range from 1000 years to 1
week, we do not find any 11.0 years period. The V-E-J configurations
do not produce any significant tidal term at this or other periods. The Venus
tidal interaction is absent in the 11-year spectral band, which is dominated by
Jupiter's orbital motion. The planet that contributes the most to the STGP in
three planets configurations, along with Venus and Earth, is Saturn. An
years tidal period with a direct physical relevance on the
11-year-like solar-activity cycle is highly improbable.Comment: (May 2023) Published in Solar Physic
Intraseasonal characterization of tropospheric O3 in the North of the Buenos Aires Province: determining four months cycle and teleconnection evidence
Tropospheric ozone (O3T) is a secondary pollutant whose formation involved
primarily solar radiation, NOx and volatile organic compounds. The North of the
Buenos Aires Province has great agricultural-industrial activity; therefore,
O3T study is an important issue in the area. In this paper, we present the
first results tend to estimate and characterize O3T in San Nicol\'as de los
Arroyos, North of Buenos Aires. Due to a lack of in situ data, we analyse the
observations of the instrument OMI (Ozone Monitoring Instrument) of land remote
sensing satellite AURA (GSFC/NASA). The data cover the years 2004-2013.
Applying the multitaper technique (MTM), very suitable for short and noisy data
series, spectral analysis is performed on a grid corresponding 1{\deg} in
latitude by 1.5{\deg} in longitude, centred South of the Province of Santa Fe.
The most remarkable result is the emergence of a significant peak (95%) of four
months cycle. To test the validity of this signal in San Nicol\'as, daily solar
radiation data (Q) were analysed in the area. The application of MTM to the
daily values of Q, yields a spectral peak of 120 days. It is concluded that
atmospheric opacity on the site has four months variations that modify the
solar radiation at the troposphere, and consequently, the production rate of
O3T. Evidence that these variations are due to teleconnection process
originated in the Maritime Continent are presented.Comment: Conference paper presented at AFA (Asociaci\'on F\'isica Argentina),
Bariloche, Argentina, September 2013; as a part of bigger paper to be
submitted to an Earth Sciences Journa
Particulate matter dynamics
A substantial fraction of the particulate matter released into the atmosphere
by industrial or natural processes corresponds to particles whose aerodynamic
diameters are greater than 50 mm. It has been shown that, for these particles,
the classical description of Gaussian plume diffusion processes, is inadequate
to describe the transport and deposition. In this paper we present new results
concerning the dispersion of coarse particulate matter. The simulations are
done with our own code that uses the Bulirsch Stoer numerical integrator to
calculate threedimensional trajectories of particles released into the
environment under very general conditions. Turbulent processes are simulated by
the Langevin equation and weather conditions are modeled after stable
(Monin-Obukhov length L> 0) and unstable conditions (L <0). We present several
case studies based on Monte Carlo simulations and discusses the effect of
weather on the final deposition of these particles.Comment: In spanish. 11 pages, 4 figs. Conference paper: Proyecto Integrador
para la Mitigaci\'on de la Contaminaci\'on Atmosf\'erica Proyecto Integrador
para la Determinaci\'on de la Calidad del Agua Tercera Reuni\'on Anual
PROIMCA Primera Reuni\'on Anual PRODECA, Agosto, 201
How the astronomical aspects of climate science were settled? On the Milankovitch and Bacsák anniversaries, with lessons for today
Covariations of chromospheric and photometric variability of the young Sun analogue HD 30495: evidence for and interpretation of mid-term periodicities
This study reports the synchronization between the chromospheric and photometric variability at time-scale of about 1.6–1.8 yr as observed for the young, rapidly rotating solar analogue HD 30495. In addition, HD 30495 may be presenting evidence of surface differential rotation at time-scales of about 11 d and 21 d, as well as the sunspot-like decadal cycles at 11–12 yr or so. We apply a new gapped wavelet method of time–frequency analysis for studying the variability in a new composite of the chromospheric S-index (1967–2018) and the longest photometric Δ(b + y)/2 index (1993–2018). We discuss and interpret our results in relation to other observed mid-term periodicities roughly of the same time-scales that had been found recently from not only chromospheric and photospheric activity indices but also from coronal X-ray emissions as observed in a considerably large set of stellar samples including those young Sun analogues from the Kepler satellite project. Thus, there is an apparent universality of such mid-term activity modulation time-scales as this solar-stellar magnetic phenomenon is well observed directly for a host of solar activity related indices covering the photopsheric, chromospheric, coronal, and even the heliospheric (utilizing the measures of incoming galactic cosmic rays as a probe of activity variations) activity records. This is why we made a further attempt to interpret the results in search of a realistic generation mechanism as well as spatio-temporal persistency of the phenomenon under a wide scenario of dynamo simulations
The Origin and Nature of Neptune-like Planets Orbiting Close to Solar Type Stars
The sample of known exoplanets is strongly biased to masses larger than the
ones of the giant gaseous planets of the solar system. Recently, the discovery
of two extrasolar planets of considerably lower masses around the nearby stars
GJ 436 and Cancri was reported. They are like our outermost icy giants,
Uranus and Neptune, but in contrast, these new planets are orbiting at only
some hundredth of the Earth-Sun distance from their host stars, raising several
new questions about their origin and constitution. Here we report numerical
simulations of planetary accretion that show, for the first time through N-body
integrations that the formation of compact systems of Neptune-like planets
close to the hosts stars could be a common by-product of planetary formation.
We found a regime of planetary accretion, in which orbital migration
accumulates protoplanets in a narrow region around the inner edge of the
nebula, where they collide each other giving rise to Neptune-like planets. Our
results suggest that, if a protoplanetary solar environment is common in the
galaxy, the discovery of a vast population of this sort of 'hot cores' should
be expected in the near future.Comment: Published by Icarus. pages:27, figs.:
Solar barycentric dynamics from a new solar-planetary ephemeris
Aims. The barycentric dynamics of the Sun has increasingly been attracting the attention of researchers from several fields, due to the idea that interactions between the Sun’s orbital motion and solar internal functioning could be possible. Existing high-precision ephemerides that have been used for that purpose do not include the effects of trans-Neptunian bodies, which cause a significant offset in the definition of the solar system’s barycentre. In addition, the majority of the dynamical parameters of the solar barycentric orbit are not routinely calculated according to these ephemerides or are not publicly available.
Methods. We developed a special version of the IAA RAS lunar–solar–planetary ephemerides, EPM2017H, to cover the whole Holocene and 1 kyr into the future. We studied the basic and derived (e.g., orbital torque) barycentric dynamical quantities of the Sun for that time span. A harmonic analysis (which involves an application of VSOP2013 and TOP2013 planetary theories) was performed on these parameters to obtain a physics-based interpretation of the main periodicities present in the solar barycentric movement.
Results. We present a high-precision solar barycentric orbit and derived dynamical parameters (using the solar system’s invariable plane as the reference plane), widely accessible for the whole Holocene and 1 kyr in the future. Several particularities and barycentric phenomena are presented and explained on dynamical bases. A comparison with the Jet Propulsion Laboratory DE431 ephemeris, whose main differences arise from the modelling of trans-Neptunian bodies, shows significant discrepancies in several parameters (i.e., not only limited to angular elements) related to the solar barycentric dynamics. In addition, we identify the main periodicities of the Sun’s barycentric movement and the main giant planets perturbations related to them