Polarity relevance in flux rope deflections triggered by coronal holes

Many observations show that coronal holes (CHs) deviate coronal mass ejections (CMEs) away from them. However, there are some peculiar events reported where the opposite occurs. To contribute to a space weather forecast efforts, in relation to the prediction of CME trajectories, we study the interaction between flux ropes (FRs) and CHs through numerical simulations. We perform 2.5D numerical simulations where FRs and CHs interact with different relative polarity configurations. We also reconstruct the trajectory and magnetic environment of a peculiar event occurred on 30 April 2012. The numerical simulations indicate that at low coronal levels, depending on the relative magnetic field polarity between the FR and the CH, the deflection will be attractive, i.e. the FR moves towards the CH (for anti-aligned polarities) or repulsive, i.e. the FR moves away to the CH (for aligned polarities). This is likely due to the formation of vanishing magnetic field regions or null points, located between the FR and the CH or, at the other side of the FR, respectively. The analysed observational event shows a double-deflection, first departing from the radial direction by approaching the CH and then moving away from it suggesting that the trajectory could result from a magnetic configuration with an anti-aligned polarity. We numerically reproduce the double deflection of the observed event, providing support to this conjecture

Three Dimensional Configuration and Evolution of Coronal Mass Ejections

Coronal mass ejections (CMEs) represent fundamental powerful processes in which energy is transferred from the Sun into interplanetary space. Their origin, 3D structure, and internal magnetic field configuration are to date not well understood. Unprecedented data provided by the instruments onboard the Solar and Heliospheric Observatory (SOHO) allow for the first time the resolution of fine structures within CMEs, which can help to deduce their 3D configuration. A set of ”structured” CMEs was identified from the full set of SOHO/LASCO observations, while their solar source regions were inferred from complementary analyses of SOHO/EIT, SOHO/MDI, and ground-based H-alpha measurements. From the characteristic distribution of the CMEs source regions, a generic scheme of 3D configuration is deduced, according to which the projected white-light topology of a CME depends primarily on the heliographic position and orientation of the source region’s underlying neutral line. The cylindrical geometry found in the structured CMEs implies that they are organized along an axial direction. Furthermore, the typical dimensions of structured CMEs exhibiting extreme projections (viewed along their axis or perpendicular to it) were investigated. The measured dimensions indicate that these CMEs would be better approximated by elliptic cones, rather than by the classical cone of circular cross section. The dimensions of halo CMEs originating near Sun center are expected to agree with those obtained for the structured events. In order to understand the CME topology better, an elliptical cone model was developed as an improvement to the existing circular cone model, in an effort to fit and reproduce a set of halo CMEs from LASCO.Koronale Massenauswürfe (Coronal Mass Ejections; CMEs) stellen neben der elektromagnetischen Strahlung und dem Sonnenwind einen weiteren fundamentalen Prozess dar, durch den Energie in den interplanetaren Raum freigesetzt wird. Die Entstehung von CMEs, ihre drei-dimensionale Struktur und Magnetfeldkonfiguration sind bis heute nicht wissenschaftlich geklärt. Zur Zeit ermöglichen Daten, aufgenommen von Instrumenten auf der Raumsonde SOHO (Solar and Heliospheric Observatory), erstmals die Auflösung feiner Strukturen innerhalb von CMEs, die zum Verständnis ihrer internen Magnetfeldstruktur und Entstehung beitragen können. Für diese Studie wurden solche „strukturierten” CMEs aus dem vollständigen Satz von SOHO/LASCO-Beobachtungen ausgewählt und deren Quellregionen mit Hilfe von komplementären Messungen der SOHO-Instrumente EIT, MDI und zusätzlichen bodengebundene H-alpha-Messungen untersucht. Basierend auf dieser Analyse konnte ein fundamentales Schema abgeleitet werden, das die drei-dimensionale Konfiguration von CMEs erklären kann. Die drei-dimensionale Struktur eines CMEs, die in den Koronagraphenaufnahmen sichtbar wird, hängt danach hauptsächlich von der heliographischen Lage und Orientierung der magnetischen Neutrallinie der CME-Quellregion ab. Die in den untersuchten CMEs gefundene zylindrische Geometrie lässt darauf schließen, dass CMEs in axialer Richtung entlang der Neutrallinie räumlich strukturiert werden und, dass diese CMEs von SOHO in extremer Projektion, d.h. entweder parallel zu ihrer Achse oder senkrecht zu ihr beobachtet wurden. Die bestimmten Dimensionen zeigen ferner, dass solche CMEs besser durch elliptische Kegelschnitte beschrieben werden, als durch kreisförmige Kegelschnitte welche in den bisherigen CME-Modellen Verwendung finden. Um die räumliche Struktur sogenannter halo CMEs zu untersuchen wurde daher ein elliptisches Kegelmodell entwickelt und an einer Reihe solcher CMEs getestet

Distorted-Toroidal Flux Rope model for Heliospheric Flux Ropes

The three-dimensional characterization of magnetic flux-ropes observed in the heliosphere has been a challenging task for decades. This is mainly due to the limitation to infer the 3D global topology and the physical properties from the 1D time series from any spacecraft. To advance our understanding of magnetic flux-ropes whose configuration departs from the typical stiff geometries, here we present the analytical solution for a 3D flux-rope model with an arbitrary cross-section and a toroidal global shape. This constitutes the next level of complexity following the elliptic-cylindrical (EC) geometry. The mathematical framework was established by Nieves-Chinchilla et al. (2018) ApJ, with the EC flux-rope model that describes the magnetic topology with elliptical cross-section as a first approach to changes in the cross-section. In the distorted-toroidal flux rope model, the cross-section is described by a general function. The model is completely described by a non-orthogonal geometry and the Maxwell equations can be consistently solved to obtain the magnetic field and relevant physical quantities. As a proof of concept, this model is generalized in terms of the radial dependence of current density components. The last part of this paper is dedicated to a specific function, $F(\varphi)=\delta(1-\lambda\cos\varphi)$, to illustrate possibilities of the model. This model paves the way to investigate complex distortions of the magnetic structures in the solar wind. Future investigations will in-depth explore these distortions by analyzing specific events, the implications in the physical quantities, such as magnetic fluxes, heliciy or energy, and evaluating the force balance with the ambient solar wind that allows such distortions.Comment: 19 pages, 8 figure

Estimating the mass of CMEs from the analysis of EUV dimmings

Context. Reliable estimates of the mass of coronal mass ejections (CMEs) are required to quantify their energy and predict how they affect space weather. When a CME propagates near the observer's line of sight, these tasks involve considerable errors, which motivated us to develop alternative means for estimating the CME mass. Aims. We aim at further developing and testing a method that allows estimating the mass of CMEs that propagate approximately along the observer's line of sight. Methods. We analyzed the temporal evolution of the mass of 32 white-light CMEs propagating across heliocentric heights of 2.5-15 R, in combination with that of the mass evacuated from the associated low coronal dimming regions. The mass of the white-light CMEs was determined through existing methods, while the mass evacuated by each CME in the low corona was estimated using a recently developed technique that analyzes the dimming in extreme-UV (EUV) images. The combined white-light and EUV analyses allow the quantification of an empirical function that describes the evolution of CME mass with height. Results. The analysis of 32 events yielded reliable estimates of the masses of front-side CMEs. We quantified the success of the method by calculating the relative error with respect to the mass of CMEs determined from white-light STEREO data, where the CMEs propagate close to the plane of sky. The median for the relative error in absolute values is ≈30%; 75% of the events in our sample have an absolute relative error smaller than 51%. The sources of uncertainty include the lack of knowledge of piled-up material, subsequent additional mass supply from the dimming region, and limitations in the mass-loss estimation from EUV data. The proposed method does not rely on assumptions of CME size or distance to the observer's plane of sky and is solely based on the determination of the mass that is evacuated in the low corona. It therefore represents a valuable tool for estimating the mass of Earth-directed events.Fil: López, F. M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Cremades Fernandez, Maria Hebe. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Balmaceda, Laura Antonia. George Mason University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Nuevo, Federico Alberto. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Vásquez, A. M.. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Universidad Nacional de Tres de Febrero; Argentin

Understanding shock dynamics in the inner heliosphere with modeling and type II radio data: A statistical study

We study two methods of predicting interplanetary shock location and strength in the inner heliosphere: (1) the ENLIL simulation and (2) the kilometric type II (kmTII) prediction. To evaluate differences in the performance of the first method, we apply two sets of coronal mass ejections (CME) parameters from the cone-model fitting and flux-rope (FR) model fitting as input to the ENLIL model for 16 halo CMEs. The results show that the ENLIL model using the actual CME speeds from FR-fit provided an improved shock arrival time (SAT) prediction. The mean prediction errors for the FR and cone-model inputs are 4.90±5.92 h and 5.48±6.11 h, respectively. A deviation of 100 km s−1 from the actual CME speed has resulted in a SAT error of 3.46 h on average. The simulations show that the shock dynamics in the inner heliosphere agrees with the drag-based model. The shock acceleration can be divided as two phases: a faster deceleration phase within 50 Rs and a slower deceleration phase at distances beyond 50 Rs. The linear-fit deceleration in phase 1 is about 1 order of magnitude larger than that in phase 2. When applying the kmTII method to 14 DH-km CMEs, we found that combining the kmTII method with the ENLIL outputs improved the kmTII prediction. Due to a better modeling of plasma density upstream of shocks and the kmTII location, we are able to provide a more accurate shock time-distance and speed profiles. The mean kmTII prediction error using the ENLIL model density is 6.7±6.4 h; it is 8.4±10.4 h when the average solar wind plasma density is used. Applying the ENLIL density has reduced the mean kmTII prediction error by ∼2 h and the standard deviation by 4.0 h. Especially when we applied the combined approach to two interacting events, the kmTII prediction error was drastically reduced from 29.6 h to −4.9 h in one case and 10.6 h to 4.2 h in the other. Furthermore, the results derived from the kmTII method and the ENLIL simulation, together with white-light data, provide a valuable validation of shock formation location and strength. Such information has important implications for solar energetic particle acceleration.Fil: Xie, H.. NASA. Goddard Space Flight Center; Estados Unidos. Department of Physics. Catholic University of America; Estados UnidosFil: St. Cyr, O.C.. NASA. Goddard Space Flight Center; Estados UnidosFil: Gopalswamy, N.. NASA. Goddard Space Flight Center; Estados UnidosFil: Odstrcil, D.. George Mason University. Department of Computational and Data Sciences; Estados UnidosFil: Cremades Fernandez, Maria Hebe. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; Argentin

Analysis of a long-duration AR throughout five solar rotations: Magnetic properties and ejective events

Coronal mass ejections (CMEs), which are among the most magnificent solar eruptions, are a major driver of space weather and can thus affect diverse human technologies. Different processes have been proposed to explain the initiation and release of CMEs from solar active regions (ARs), without reaching consensus on which is the predominant scenario, and thus rendering impossible to accurately predict when a CME is going to erupt from a given AR. To investigate AR magnetic properties that favor CMEs production, we employ multi-spacecraft data to analyze a long duration AR (NOAA 11089, 11100, 11106, 11112 and 11121) throughout its complete lifetime, spanning five Carrington rotations from July to November 2010. We use data from the Solar Dynamics Observatory to study the evolution of the AR magnetic properties during the five near-side passages, and a proxy to follow the magnetic flux changes when no magnetograms are available, i.e. during far-side transits. The ejectivity is studied by characterizing the angular widths, speeds and masses of 108 CMEs that we associated to the AR, when examining a 124-day period. Such an ejectivity tracking was possible thanks to the multi-viewpoint images provided by the Solar-Terrestrial Relations Observatory and Solar and Heliospheric Observatory in a quasi-quadrature configuration. We also inspected the X-ray flares registered by the GOES satellite and found 162 to be associated to the AR under study. Given the substantial number of ejections studied, we use a statistical approach instead of a single-event analysis. We found three well defined periods of very high CMEs activity and two periods with no mass ejections that are preceded or accompanied by characteristic changes in the AR magnetic flux, free magnetic energy and/or presence of electric currents. Our large sample of CMEs and long term study of a single AR, provide further evidence relating AR magnetic activity to CME and Flare production.Fil: Iglesias, Francisco Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Cremades Fernandez, Maria Hebe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Merenda, Luciano A.. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Lopez Fuentes, Marcelo Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Lopez Fuentes, Marcelo Claudio. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Ugarte Urra, Ignacio. Spece Sciences División. Naval Research Laboratory; Estados Unido

Ondas de radio kilométricas de tipo II generadas por ECMs: relación con estructuras interplanetarias y grado de geoefectividad

Se analizaron espectros dinámicos del receptor WAVES/TNR (Thermal Noise Receiver) a bordo de la misión espacial Wind entre el 01/01/2000 y el 31/12/2012, en búsqueda de eventos de radio de tipo II kilométricos (kmTII). Se construyó una base de datos que interrelaciona las características de emisiones de radio de baja frecuencia con estructuras interplanetarias detectadas in situ potencialmente asociadas a dichas emisiones de radio. Se encontraron un total de 105 eventos, de los cuales 32 no se encuentran catalogados en la lista de eventos de tipo II de Wind/WAVES . Además, 46 eventos se asociaron con detecciones in situ de eyecciones coronales de masa interplanetarias (ECMIs), con 36 de éstos presentando características de nube magnética (NM). Para 74 eventos se obtuvieron los valores del índice Dst (Disturbance Storm Time, por sus siglas en inglés) correspondiente, a fin de estudiar la geoefectividad de eventos con una ECMI o NM asociada. Para este grupo de estructuras interplanetarias asociadas a kmTII, se encontró que aquellos responsables de las tormentas geomagnéticas más intensas ocurrieron cerca del máximo de actividad solar. Por otro lado, se encontró que las mayores tormentas pueden ser atribuidas a ECMIs con características de NM. Mientras que los eventos de sólo ondas de choque, y ECMIs sin características de NM, se asociaron a tormentas de menor intensidad.Fil: Manini Gomez, Franco Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Cremades Fernandez, Maria Hebe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: López, Fernando Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; Argentina. Universidade Presbiteriana Mackenzie; Brasil62a Reunión de la Asociación Argentina de AstronomíaRosarioArgentinaAsociación Argentina de Astronomí

Daytime Sky Quality at El Leoncito, Argentina

We characterize the daytime sky quality in terms of brightness, cloud coverage, and main weather variables at the Carlos Ulrico Cesco station of the Felix Aguilar Astronomical Observatory (OAFA), located in El Leoncito National Park, San Juan, Argentina. We have collected more than 15 years of daily observations from the auxiliary sky brightness detectors of the Mirror Coronagraph for Argentina (MICA, in operations from 1997 to 2012), including daily observing reports. We additionally present data from two meteorological stations operated at the site from 2000 to 2020. We determine the main statistical properties and seasonal variability of daytime sky brightness, clear sky time fraction (CSTF), precipitable water vapor (WV), temperature, humidity, and wind speed, which are relevant for solar, particularly coronal observations. Our results confirm that El Leoncito is an excellent place to perform daytime astronomical observations. We measure a median sky brightness of 15.8 ppm, estimated at 526.0 ± 1.0 nm and 6 solar radii from the solar disk center; a median CSTF of 0.7; and a median WV below 6 mm. These values, and those of other relevant weather variables, are comparable to the levels found among the best astronomical observing sites in the world. Due to the extended period of time analyzed and high sampling frequency, the novel data and results presented in this report contribute to the analysis and interpretation of historical sky brightness data and are of great value for the future planning of daytime astronomical instrumentation at El Leoncito.Fil: Iglesias, F. A.. Universidad de Mendoza. Facultad de Ingenieria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Francile, Carlos Natale. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Informática. Observatorio Astronómico Félix Aguilar; ArgentinaFil: Lazarte Gelmetti, J.. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Balmaceda, L. A.. George Mason University. School Of Physics. Astronomy And Computational Sciences; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Cremades Fernandez, Maria Hebe. Universidad de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cisterna, F.. Universidad de Mendoza. Facultad de Ingenieria; Argentin

Configuración magnética pre-eruptiva de la región NOAA 12127 mediante extrapolación no lineal del campo

Estudiamos las propiedades magnéticas de la región activa NOAA 12127 previas a una fulguración clase M1.5, acompañada de una eyección coronal de masa, el 1 de agosto de 2014. Estimamos su campo magnético coronal preeruptivo mediante una extrapolación no lineal libre de fuerza y comparamos los resultados con imágenes en Hα y 171 ˚A. El campo extrapolado logra reproducir la morfología de configuraciones magnéticas asociadas a un filamento y arcos coronales, identificados en la región.We studied the magnetic properties of active region NOAA 12127 previous to a M1.5-class flare, that was accompanied by a coronal mass ejection, on the August 1, 2014. We estimated the pre-eruptive coronal magnetic field using a non-linear, force-free extrapolation, and compared the results with images in Hα and 171 ˚A. The extrapolated field is able to reproduce the general morphology of the magnetic configurations linked to a filament and several coronal loops identified.Fil: Merenda, Luciano A.. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Iglesias, Francisco Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Cremades Fernandez, Maria Hebe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; Argentina62º Reunión Anual de la Asociación Argentina de AstronomíaRosarioArgentinaAsociación Argentina de AstronomíaUniversidad Nacional de Rosari

Large non-radial propagation of a coronal mass ejection on 2011 January 24

Understanding the deflection of coronal mass ejections (CMEs) is of great interest to the space weather community because of their implications for improving the prediction of CME. This paper aims to shed light into the effects of the coronal magnetic field environment on CME trajectories. We analyze the influence of the magnetic environment on the early development of a particular CME event. On 2011 January 24 an eruptive filament was ejected in association with a CME that suffered a large deflection from its source region and expected trajectory. We characterize the 3D evolution of the prominence material using the tie-pointing/triangulation reconstruction technique on EUV and white-light images. To estimate the coordinates in 3D space of the apex of the CME we use a forward-modeling technique that reproduces the large-scale structure of the flux rope-like CME, the Graduated Cylindrical Shell model. We found that the deflection amounts to 42° in latitude and 20° in longitude and that most of it occurs at altitudes below 4R⊙. Moreover, we found a non-negligible deflection at higher altitudes. Combining images of different wavelengths with the extrapolated magnetic field obtained from a potential field source surface model we confirm the presence of two magnetic structures near the erupting event. The magnetic field environment suggests that field lines from the southern coronal hole act as a magnetic wall that produces the large latitudinal deflection; while a nearby pseudostreamer and a northward extension of the southern coronal hole may be responsible for the eastward deflection of the CME.Fil: Cécere, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Sieyra, María Valeria. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cremades Fernandez, Maria Hebe. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mierla, M.. Institute of Geodynamics of the Romanian Academy; BélgicaFil: Sahade, Abril. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Stenborg, G.. Spece Sciences División. Naval Research Laboratory; Estados UnidosFil: Costa, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: West, M. J.. Royal Observatory Of Belgium; BélgicaFil: D'Huys, E.. Royal Observatory Of Belgium; Bélgic