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

3D numerical model of the Omega Nebula (M17): simulated thermal X-ray emission

We present 3D hydrodynamical simulations of the superbubble M17, also known as the Omega nebula, carried out with the adaptive grid code yguazu'-a, which includes radiative cooling. The superbubble is modelled considering the winds of 11 individual stars from the open cluster inside the nebula (NGC 6618), for which there are estimates of the mass loss rates and terminal velocities based on their spectral types. These stars are located inside a dense interstellar medium, and they are bounded by two dense molecular clouds. We carried out three numerical models of this scenario, considering different line of sight positions of the stars (the position in the plane of the sky is known, thus fixed). Synthetic thermal X-ray emission maps are calculated from the numerical models and compared with ROSAT observations of this astrophysical object. Our models reproduce successfully both the observed X-ray morphology and the total X-ray luminosity, without taking into account thermal conduction effects.Comment: 8 pages, 6 figures, accepted for publication in MNRA

Testing bias adjustment methods for regional climate change applications under observational uncertainty and resolution mismatch

Systematic biases in climate models hamper their direct use in impact studies and, as a consequence, many statistical bias adjustment methods have been developed to calibrate model outputs against observations. The application of these methods in a climate change context is problematic since there is no clear understanding on how these methods may affect key magnitudes, for example, the climate change signal or trend, under different sources of uncertainty. Two relevant sources of uncertainty, often overlooked, are the sensitivity to the observational reference used to calibrate the method and the effect of the resolution mismatch between model and observations (downscaling effect). In the present work, we assess the impact of these factors on the climate change signal of temperature and precipitation considering marginal, temporal and extreme aspects. We use eight standard and state-of-the-art bias adjustment methods (spanning a variety of methods regarding their nature—empirical or parametric—, fitted parameters and trend-preservation) for a case study in the Iberian Peninsula. The quantile trend-preserving methods (namely quantile delta mapping (QDM), scaled distribution mapping (SDM) and the method from the third phase of ISIMIP-ISIMIP3) preserve better the raw signals for the different indices and variables considered (not all preserved by construction). However, they rely largely on the reference dataset used for calibration, thus presenting a larger sensitivity to the observations, especially for precipitation intensity, spells and extreme indices. Thus, high-quality observational datasets are essential for comprehensive analyses in larger (continental) domains. Similar conclusions hold for experiments carried out at high (approximately 20 km) and low (approximately 120 km) spatial resolutions. © 2020 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society

Assessing multidomain overlaps and grand nnsemble generation in CORDEX regional projections

ABSTRACT: The Coordinated Regional Climate Downscaling Experiment (CORDEX) initiative has made available an enormous amount of regional climate projections in different domains worldwide. This information is crucial for the development of adaptation strategies and policy-making. A relevant open issue in this context is assessing the potential multidomain conflicts that may result in overlapping regions and developing appropriate ensemble methods trying to make the most of all available information. This work addresses this timely topic by focusing on precipitation over the Mediterranean region, a first illustrative case study that is encompassed by both the Euro- and Africa-CORDEX domains. We focus on several mean, extreme, and temporal indices and use variance decomposition to assess the separate contribution of the domain and models to the climate change signal, concluding that the contribution of the domain alone is nearly negligible (below urn:x-wiley:grl:media:grl60267:grl60267-math-0001 in all cases). Nevertheless, for some cases, the combined model/domain effect triggers up to urn:x-wiley:grl:media:grl60267:grl60267-math-0002 of the total variance.This work has been funded by the Spanish R+D Program of the Ministry of Economy and Competitiveness, through projects MULTI-SDM (CGL2015-66583-R) and INSIGNIA (CGL2016-79210-R), cofunded by the European Regional Development Fund (ERDF/FEDER)

X-ray emission and dynamics from large diameter superbubbles: The case of N 70 superbubble

The morphology, dynamics and thermal X-ray emission of the superbubble N70 is studied by means of 3D hydrodynamical simulations, carried out with the {\sc{yguaz\'u-a}} code. We have considered different scenarios: the superbubble being the product of a single supernova remnant, of the stellar winds from an OB association, or the result of the joint action of stellar winds and a supernova event. Our results show that, in spite that all scenarios produce bubbles with the observed physical size, only those where the bubble is driven by stellar winds and a SN event are successful to explain the general morphology, dynamics and the X-ray luminosity of N70. Our models predict temperatures in excess of $10^8 \mathrm{K}$ at the interior of the superbubble, however the density is too low and the emission in thermal X-ray above $2 \mathrm{keV}$ is too faint to be detected.Comment: 9 pages, 11 figures, ApJ accepte

Aplicación de biología molecular en veterinaria: Pcr como método de diagnóstico para investigar presencia de Escherichia Coli productora de Verotoxina (Vtec) en caninos de zonas rurales y periurbanas. Su implicancia en salud pública

El síndrome urémico hemolítico (SUH) se caracteriza por anemia hemolítica microangiopática, plaquetopenia y daño renal. Constituye la primera causa de insuficiencia renal aguda en la edad pediátrica y la segunda de insuficiencia renal crónica. Escherichia coli productor de verotoxina es el primer agente etiológico de SUH. Los objetivos del presente trabajo son determinar si los perros pueden constituir un riesgo para la salud pública como portadores de VTEC y poner a punto la técnica de la reacción en cadena de la polimerasa (PCR). Hasta la fecha se han tomado 26 muestras de zonas peri urbanas y de caninos de la Sociedad Mendocina Protectora de Animales (SMPA). Las muestras fueron obtenidas mediante hisopado rectal de caninos y fueron sembradas en el medio de cultivo selectivo Agar Mac Conkey Sorbitol y Agar Levine e incubadas 24 horas a 37°C