Slow magnetoacoustic gravity waves in an equilibrium stratified solar atmosphere: Cut-offperiods through the transition region

Assuming the thin flux tube approximation, we introduce an analytical model that contemplates the presence of a non-isothermal temperature, a varying magnetic field, and a non-uniform stratified medium in hydrostatic equilibrium due to a constant gravity acceleration. This allows the study of slow magnetoacoustic cut-offperiods across the solar transition region, from the base of the solar chromosphere to the lower corona. The used temperature profile approaches the solar atmospheric model of G18. The periods obtained are consistent with observations. Similar to the acoustic cut-offperiods, the resulting magnetoacoustic gravity ones follow the sharp temperature profile, but shifted towards larger heights; in other words, at a given height the magnetoacoustic cut-offperiod is significantly lower than the corresponding acoustic one. Along a given longitude of an inclined thin magnetic tube, the greater its inclination the softer the temperature gradient it crosses. Changes in the magnetic field intensity do not significantly modify the periods at the coronal level but modulate the values below the transition region within periods between ~[2-6] min. Within the limitations of our model, we show that monochromatic oscillations of the solar atmosphere are the atmospheric response at its natural frequency to random or impulsive perturbations, and not a consequence of the forcing from the photosphere.Fil: Costa, 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: Schneiter, Ernesto Matías. 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: Zurbriggen, Ernesto. 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; Argentin

3D MHD simulation of flare supra-arcade downflows in a turbulent current sheet medium

Supra-arcade downflows (SADs) are sunward, generally dark, plasma density depletions originated above posteruption flare arcades. In this paper, using 3D MHD simulations we investigate whether the SAD cavities can be produced by a direct combination of the tearing mode and Kelvin-Helmholtz instabilities leading to a turbulent current sheet (CS) medium or if the current sheet is merely the background where SADs are produced, triggered by an impulsive deposition of energy. We find that to give an account of the observational dark lane structures an addition of local energy, provided by a reconnection event, is required. We suggest that there may be a closed relation between characteristic SAD sizes and CS widths that must be satisfied to obtain an observable SAD.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: Zurbriggen, Ernesto. 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: Costa, Andrea. Universidad Nacional de Córdoba; Argentina. 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: Schneiter, Ernesto Matías. 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; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentin

Obtención de compuesto de titanio con gradiente de porosidad mediante técnica pulvimetalúrgica

Within the study of biomaterials for implantological use titanium is among the most widely employed metals due to its excellent corrosion and mechanical resistance. In spite of the advances made, there are some issues remaining with the value of the elastic moduli of the titanium (110GPa) in comparison with the elastic moduli of the cortical bone (20-30 GPa) and the trabecular bone (1-5GPa). This difference is one of the main reasons a bone prosthesis fails once implanted, producing what is known as Stress shielding. One of the techniques employed to diminish the elastic moduli of titanium consists in incorporating pores to the material. This is done through powder metallurgy techniques, allowing the fabrications of porous composites, sintering a mix of powders of metallic hydrides and spacers that are eliminated during the heat treatment. Taking into account the structural characteristics of the bone, it makes sense to think on the possibility of fabricating a prosthesis with pore gradients. Another problem encountered when employing titanium, is its inability to promote the osteointegration. There are different techniques to tackle this problem, and one of them is to incorporate hydroxyapatite which has the problem that it decomposes in the presence of titanium when sintered at high temperatures. The current study shows the results obtained during the fabrication of samples of titanium with pore gradients. We studied different fabrication techniques, analyzing each stage during the powder metallurgy. process. The obtained material was characterized mechanically through compression tests, determining the elastic moduli of the composite, which was found to be between 16.4 and 20 GPa. Also, different physical characterization methods where employed to analyse the pore content which was found to be 18%. The obtained data was employed for the estimation of elastic moduli of the compound, and compared to the empirical results obtained with the mechanical tests.Fil: Grinschpun, Luciano. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; ArgentinaFil: Oldani, Carlos Rodolfo. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; ArgentinaFil: Schneiter, Ernesto Matías. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; Argentina. 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: Valdemarin, Matías. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; ArgentinaFil: Pereyra, Juan. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; Argentin

Magnetized winds and their influence in the escaping upper atmosphere of HD 209458b

Lyman a observations during an exoplanet transit have proved to be very useful to study the interaction between the stellar wind and the planetary atmosphere. They have been extensively used to constrain planetary system parameters that are not directly observed, such as the planetary mass-loss rate. In this way, Ly α observations can be a powerful tool to infer the existence of a planetarymagnetic field, since it is expected that the latterwill affect the escaping planetary material. To explore the effect that magnetic fields have on the Ly α absorption of HD 209458b, we run a set of 3D MHD simulations including dipolar magnetic fields for the planet and the star. We assume values for the surface magnetic field at the poles of the planet in the range of [0-5] G, and from 1 to 5 G at the poles of the star. Our models also include collisional and photo-ionization, radiative recombination, and an approximation for the radiation pressure. Our results show that the magnetic field of the planet and the star change the shape of the Ly α absorption profile, since it controls the extent of the planetary magnetosphere and the amount of neutralmaterial inside it. Themodel that best reproduces the absorption observed in HD 209458b (with canonical values for the stellar wind parameters) corresponds to a dipole planetary field of ≲ 1 G at the poles.Fil: Villarreal D'angelo, Carolina Susana. University of St. Andrews; Reino UnidoFil: Esquivel Salazar, José Alejandro. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; MéxicoFil: Schneiter, Ernesto Matías. 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: Sgró, Mario Agustín. 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; Argentin

3D hydrodynamic numerical models for nebulae around runaway Wolf-Rayet stars

We present 3D hydrodynamical simulations of the circumstellar bubble from a Wolf-Rayet runaway star. In the models two properties were taken into account: (a) the proper motion of the central star through the interstellar medium (ISM) and (b) the evolution of the stellar wind from the red supergiant (RSG) stage to the Wolf-Rayet (WR) stage. From the hydrodynamic results synthetic X-ray maps in the [0.3 − 1.2] keV energy range were computed. These maps show that the bubble morphology is affected by the stellar motion, producing a bow shock in the RSG stage that can explain the limb-brightened morphology observed. Additionally, these synthetic maps show filamentary and clumpy appearance produced by instabilities triggered from the interaction between the WR wind and the RSG shell. It was found that these types of collisions can explain the origin of the X-ray emission observed in the nebulae of Wolf- Rayet stars.Fil: Reyes Iturbide, J.. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; México. Tecnológico de Estudios Superiores de Tianguistenco; MéxicoFil: Velázquez, Pablo F.. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; MéxicoFil: Rosado, M.. Universidad Nacional Autónoma de México. Instituto de Astronomía; MéxicoFil: Schneiter, Ernesto Matías. 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: Ramírez Ballinas, I.. Universidad Nacional Autónoma de México. Instituto de Astronomía; Méxic

Hydrodynamical interaction of stellar and planetary winds: Effects of charge exchange and radiation pressure on the observed Ly α absorption

Lyman α observations of the transiting exoplanet HD 209458b enable the study of exoplanet exospheres exposed to stellar extreme ultraviolet (EUV) fluxes, as well as the interacting stellar wind properties. In this study we present 3D hydrodynamical models for the stellar-planetary wind interaction including radiation pressure and charge exchange, together with photoionization, recombination, and collisional ionization processes. Our models explore the contribution of the radiation pressure and charge exchange to the Ly α absorption profile in a hydrodynamical framework, and for a single set of stellar wind parameters appropriate for HD 209458. We find that most of the absorption is produced by the material from the planet, with a secondary contribution of neutralized stellar ions by charge exchange. At the same time, the hydrodynamic shock heats up the planetary material, resulting in a broad thermal profile. Meanwhile, the radiation pressure yields a small velocity shift of the absorbing material. While neither charge exchange nor radiation pressure provides enough neutrals at the velocity needed to explain the observations at -100 km s-1 individually, we find that the two effects combined with the broad thermal profile are able to explain the observations.Fil: Esquivel, A.. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; México. 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: Schneiter, Ernesto Matías. 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; Argentina. Stockholms Universitet; SueciaFil: Villarreal D'angelo, Carolina Susana. 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: Sgró, Mario Agustín. 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: Krapp, Leonardo Javier. Stockholms Universitet; Suecia. 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; Argentin

Espuma ultraliviana de Mg a partir de viruta reciclada

Hundreds of people worldwide die or are severely maimed in collisions during traffic accidents, due to the energy transmitted to the passengers on impact. A dissipation of said energy is necessary to minimize it's effects, which can be achieved through absorbers. In recent years, metallic foams have started to be considered as energy absorbers. Metallic foams are relatively unknown structural materials, but with huge potential for applications where low weight but high rigidity are of primary interest. The use of ultralight magnesium (Mg) or magnesium alloy foams has two main advantages: less weight (more vehicle efficiency and less pollution) and impact energy absorption (less harm to passengers on board the vehicle). The machining of gearboxes made out of AZ91D magnesium alloy, generates large amounts of oilcontaminated metallic shavings. In this work, powder metallurgy is used as a recycling method of the AZ91 alloy. There were studied the conditions needed for obtaining metallic foam from recycled shavings of AZ91 and spacer (ammonium bicarbonate). The final product was characterized physically by determination of the foam's density. Also, compression tests were done to obtain values of absorbed energy, and specific absorbed energy, which characterize a metallic foam. Different metallography methods were used to characterize the structure of the sintered material. Different porosities were tested (50 and 70%). The foam's absorbed energy by unit mass [J/g] of the 50 % of porosity foam was over double compared to that of the magnesium sintered without spacer.Fil: Oldani, Carlos Rodolfo. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; ArgentinaFil: Grinschpun, Luciano. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; ArgentinaFil: Schneiter, Ernesto Matías. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; Argentina. 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: Milne, Rodrigo. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Daniel Acciarri. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; ArgentinaFil: Noam Abadi. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Materiales y Tecnología; Argentin

Machine learning on difference image analysis: A comparison of methods for transient detection

We present a comparison of several Difference Image Analysis (DIA) techniques, in combination with Machine Learning (ML) algorithms, applied to the identification of optical transients associated to gravitational wave events. Each technique is assessed based on the scoring metrics of Precision, Recall, and their harmonic mean F1, measured on the DIA results as standalone techniques, and also in the results after the application of ML algorithms, on transient source injections over simulated and real data. These simulations cover a wide range of instrumental configurations, as well as a variety of scenarios of observation conditions, by exploring a multi dimensional set of relevant parameters, allowing us to extract general conclusions related to the identification of transient astrophysical events. The newest subtraction techniques, and particularly the methodology published in Zackay et al., (2016) are implemented on an Open Source Python package, named properimage, suitable for many other astronomical image analyses. This together, with the ML libraries we describe, provides an effective transient detection software pipeline. Here we study the effects of the different ML techniques, and the relative feature importances for classification of transient candidates, and propose an optimal combined strategy. This constitutes the basic elements of pipelines that could be applied in searches of electromagnetic counterparts to GW sources.Fil: Sánchez, Bruno Orlando. 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; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Dominguez Romero, Mariano Javier de Leon. 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; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Lares Harbin Latorre, Marcelo. 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; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Beroiz, Martin Isidro Ramon. University of Texas; Estados UnidosFil: Cabral, Juan Bautista. 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; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Gurovich, Sebastian. 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: Quiñones, Cecilia. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Artola, Rodolfo Alfredo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Colazo, Carlos 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: Schneiter, Ernesto Matías. 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: Girardini, Carla. 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: Tornatore, Marina. 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: Nilo Castellón, José Luis. Universidad de La Serena; ChileFil: Garcia Lambas, Diego Rodolfo. 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; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Díaz, Mario Coma. University of Texas At Brownsville. Center for Gravitational Wave Astronomy; Estados Unido

Refined physical parameters for Chariklo's body and rings from stellar occultations observed between 2013 and 2020

Context. The Centaur (10199) Chariklo has the first ring system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow sizes and shapes to be determined with kilometre accuracy, and provide the characteristics of the occulting object and its vicinity. Aims. Using stellar occultations observed between 2017 and 2020, our aim is to constrain the physical parameters of Chariklo and its rings. We also determine the structure of the rings, and obtain precise astrometrical positions of Chariklo. Methods. We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the datasets, from which ingress and egress times, and the ring widths and opacity values were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo's shape and ring structure. Results. We characterise Chariklo's ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirm the detection of W-shaped structures within C1R and an evident variation in radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating a ring particle size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3σ), and its width variations may indicate an eccentricity higher than ~0.005. We fit a tri-axial shape to Chariklo's detections over 11 occultations, and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8-1.5+1.4, 135.2-2.8+1.4, and 99.1-2.7+5.4 km. Ultimately, we provided seven astrometric positions at a milliarcsecond accuracy level, based on Gaia EDR3, and use it to improve Chariklo's ephemeris.Fil: Morgado, B.E.. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Sicardy, Bruno. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Braga Ribas, Felipe. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; Brasil. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia. Universidade Tecnologia Federal do Parana; BrasilFil: Desmars, Josselin. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Gomes Júnior, Altair Ramos. Universidade de Sao Paulo; BrasilFil: Bérard, D.. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Leiva, Rodrigo. Universidad de Chile; Chile. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Vieira Martins, Roberto. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Benedetti Rossi, G.. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia. Universidade Federal de Sao Paulo; BrasilFil: Santos Sanz, Pablo. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Camargo, Julio Ignacio Bueno. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Duffard, R.. Universidade Federal do Rio de Janeiro; BrasilFil: Rommel, F.L.. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Assafin, M.. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Boufleur, R.C.. Universidad Nacional de Córdoba; ArgentinaFil: Colas, F.. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Kretlow, Mike. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Beisker, W.. University of North Carolina; Estados UnidosFil: Sfair, Rafael. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Snodgrass, Colin. University of Edinburgh; Reino UnidoFil: Morales, N.. Pontificia Universidad Católica de Chile; Chile. Universidad Católica de Chile; ChileFil: Fernández Valenzuela, E.. Pontificia Universidad Católica de Chile; Chile. Universidad Católica de Chile; ChileFil: Amaral, L.S.. Massachusetts Institute of Technology; Estados UnidosFil: Amarante, A.. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Artola, R.A.. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Backes, M.. Universidad Nacional de Córdoba; ArgentinaFil: Bath, K. L.. University of North Carolina; Estados UnidosFil: Bouley, S.. University of St. Andrews; Reino UnidoFil: Garcia Lambas, Diego Rodolfo. 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: Schneiter, Ernesto Matías. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Ingeniería Económica y Legal; Argentina. 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; Argentin

MHD simulations of coronal supra-arcade downflows including anisotropic thermal conduction

Coronal supra-arcade downflows (SADs) are observed as dark trails descending toward hot turbulent-fan-shaped regions. Due to the large temperature values and gradients in these fan regions, the thermal conduction (TC) should be very efficient. While several models have been proposed to explain the triggering and the evolution of SADs, none of these scenarios address a systematic consideration of TC. Thus, we accomplish this task numerically simulating the evolution of SADs within this framework. That is, SADs are conceived as voided (subdense) cavities formed by nonlinear waves triggered by downflowing bursty localized reconnection events in a perturbed hot fan. We generate a properly turbulent fan, obtained by a stirring force that permits control of the energy and vorticity input in the medium where SADs develop. We include anisotropic TC and consider plasma properties consistent with observations. Our aim is to study whether it is possible to prevent SADs from vanishing by thermal diffusion. We find that this will be the case, depending on the turbulence parameters, in particular if the magnetic field lines are able to envelope the voided cavities, thermally isolating them from the hot environment. Velocity shear perturbations that are able to generate instabilities of the Kelvin-Helmholtz type help to produce magnetic islands, extending the lifetime of SADs.Fil: Zurbriggen, Ernesto. 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: Costa, 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: Esquivel, A.. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; MéxicoFil: Schneiter, Ernesto Matías. 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: 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; Argentin