Ministerio de Economía y Competitividad Gobierno de Canarias Universidad de La Laguna CSIC Centro de Excelencia Severo Ochoa

Astrophysics Research Projects

The Sun and Solar System

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Numerical Simulation of Astrophysical Processes (P/300313)

M LUNA BENNASAR

Fernando Moreno Insertis, Daniel E. Nóbrega Siverio, Ángel de Vicente Garrido, Tobias Felipe García, Pedro A. González Morales, Beatrice Popescu Brailenau, Nikolas Vitas, Javier Trujillo Bueno, Andrés Asensio Ramos, Héctor Socas Navarro, Elena Khomenko, Iñigo Arregui Uribe-Echevarria

K. Galsgaard (Niels Bohr Institute/Univ. Copenhague), J. Martínez Sykora (Lockheed Martin Solar and Astrophysical Laboratory), V. Hansteen (Univ. Oslo); E. Priest (Univ St Andrews), N. Shchukina (Obs. Kiev); J. Stepan (Astronomical Institute ASCR, Ondrejov), M. Madjarska (Max Planck Institute for Solar System Research, Gottingen), L. Belluzzi (Obs Locarno), T. del Pino (HAO), V. Olshevsky (Katholic Univ. Leuven); P. Cally, S. Shelyag (Monash Univ. Melbourne); M. Stangalini (Univ. Tor Vergata, Roma), I. Calvo Santamaria (Katholieke Univ. Leuven), J. Klimchuk (NASA Goddard); T. Kucera, K. Muglach, H. Gilbert, J. Karpen (NASA Goddard Space Flight Center), B. Schmieder (LESIA, Paris), Dr. Ramesh Chandra (Kumaun University, Nainita).

Introduction

The general aim of this project is the investigation of astrophysical processes through the use of state-of-the-art numerical codes on massively parallel computers. More specifically, the research in many astrophysical fields requires understanding of gas dynamical, magnetic, radiative transfer and gravitational phenomena not accessible to purely theoretical analysis. In the framework of this project calculations aimed at understanding the multidimensional structure and evolution of magnetic fields in stellar atmospheres and interiors are carried out, including magnetohydrodynamical aspects, radiative transfer and spectral line polarization. Special emphasis is placed on the comparison of the theoretical/numerical results with observational data.

Milestones

The first numerical model in three dimensions of the solar coronal bright points has been obtained. The coronal bright points are, like the bright loops and the coronal holes, a basic structure of the hot (1 million degree) atmosphere above photosphere and chromosphere. Coronal bright points have been systematically observed to appear all over the solar disk by the large solar satellite missions like Yohkoy, SOHO, SDO, HInode, Stereo, in the Extreme Ultraviolet and X-Ray ranges. There was so far no encompassing explanation of those phenomena on the basis of a full solution of the magnetohydrodynamic equations, including magnetic field line reconnection episodes, stratification of the plasma andits time evolution in interaction with the magnetic field. An important difficulty is that the reconnection processes change their nature when taking place in three-dimensional structures, leading to complicated magnetic connectivity changes. On the other hand, the observational advances of the past years clearly indicated that to understand the bright point phenomenon an in-depth study of three-dimensional reconnection in coronal structures overlying bipolar regions in the supergranular network was necessary. In our study we show how the stressing of a magnetic null-point structure in the corona caused by the motion of its photospheric footpoints leads to reconnection, magnetic energy release in the form of ohmic heating, and creation of coronal structures that can explain the appearance of bright points in the EUV and X-Ray observations.

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