Magnestismo Solar y Estelar

    General
    Descripción

    Los campos magnéticos son uno de los ingredientes fundamentales en la formación de estrellas y su evolución. En el nacimiento de una estrella, los campos magnéticos llegan a frenar su rotación durante el colapso de la nube molecular, y en el fin de la vida de una estrella, el magnetismo puede ser clave en la forma en la que se pierden las capas externas de forma dramática. En la vida adulta, el magnetismo da lugar a la actividad de las estrellas. Nuestro Sol tiene campos magnéticos que dan lugar a una actividad tan espectacular que es capaz de tener un impacto en la Tierra. Pero en otras estrellas, la actividad magnética es, en algunos casos, órdenes de magnitud más intensa que la solar, influenciando drásticamente el transporte de especies químicas y de momento angular, así como afectando posibles sistemas planetarios alrededor de éstas.

    La finalidad de este Proyecto es estudiar diversas manifestaciones del campo magnético que se pueden observar en la atmosfera solar y en otras estrellas. Estas incluyen estructuras tan diversas como las manchas solares, los campos débiles presentes en el sol en calma o estructuras cromosféricas y coronales como los filamentos y las protuberancias. Así, se han ido abordando gradualmente los siguientes temas de investigación:

     

    Magnetismo solar

    1. Estructura y evolución del campo magnético en manchas solares.
    2. Estructura y evolución del campo magnético en el Sol en calma.
    3. Estructura y evolución del campo magnético en la cromosfera y en estructuras cromosféricas (protuberancias, espículas,...)
    4. Estructura y evolución del campo magnético en bucles coronales.
    5. Estructura y evolución del campo magnético global del Sol. Estudios del ciclo de actividad magnética.
    6. Estudio empírico de la propagación de ondas magnetohidrodinámicas en el seno de estructuras magnéticas.
    7. Estudio empírico de mecanismos relacionados con el calentamiento de las capas externas del Sol.
    8. Estudio empírico de la influencia de la ionización parcial en la dinamica de la atmosfera solar.
    9. Implicación en el proyecto del Telescopio Solar Europeo.

    Magnetismo estelar

    1. Desarrollo de métodos numéricos para el diagnóstico del campo magnético estelar, tanto en la superficie como en la cromosfera.
    2. Estudio del magnetismo en protuberancias estelares.
    3. Impacto del campo magnético en las últimas fases de la evolución estelar.
    Investigador principal
    Personal del proyecto
    1. Ondas espirales en manchas solares: Se han interpretado como ondas magnetoacústicas que se propagan desde el interior hasta capas atmosféricas siguiendo la dirección del campo magnético. Se ha caracterizado la topología del campo magnético de la mancha, descartando que la forma espiral sea consecuencia del retorcimiento de las líneas de campo (Felipe et al. 2019).
    2. Respuesta magnética a umbral flashes: Observaciones espectropolarimétricas simultáneas de las líneas cromosféricas He I 10830 y Ca II 8542 fueron usadas para estimar las fluctuaciones del campo magnético asociado a ondas de choque. Los choques provocan la expansión de las líneas de campo (Houston et al. 2018, incluye a A. Asensio Ramos).

    Publicaciones relacionadas

    • Fast-to-Alfvén Mode Conversion Mediated by the Hall Current. I. Cold Plasma Model
      The photospheric temperature minimum in the Sun and solar-like stars is very weakly ionized, with an ionization fraction f as low as 10‑4. In galactic star-forming regions, f can be 10‑10 or lower. Under these circumstances, the Hall current can couple low-frequency Alfvén and magnetoacoustic waves via the dimensionless Hall parameter ε =ω /{{{Ω }}
      Cally, P. S. et al.

      Fecha de publicación:

      12
      2015
      Número de citas
      29
    • Damped transverse oscillations of interacting coronal loops
      Damped transverse oscillations of magnetic loops are routinely observed in the solar corona. This phenomenon is interpreted as standing kink magnetohydrodynamic waves, which are damped by resonant absorption owing to plasma inhomogeneity across the magnetic field. The periods and damping times of these oscillations can be used to probe the physical
      Soler, R. et al.

      Fecha de publicación:

      10
      2015
      Número de citas
      7
    • Model Comparison for the Density Structure across Solar Coronal Waveguides
      The spatial variation of physical quantities, such as the mass density, across solar atmospheric waveguides governs the timescales and spatial scales for wave damping and energy dissipation. The direct measurement of the spatial distribution of density, however, is difficult, and indirect seismology inversion methods have been suggested as an
      Arregui, I. et al.

      Fecha de publicación:

      10
      2015
      Número de citas
      24
    • On the Source of Propagating Slow Magnetoacoustic Waves in Sunspots
      Recent high-resolution observations of sunspot oscillations using simultaneously operated ground- and space-based telescopes reveal the intrinsic connection between different layers of the solar atmosphere. However, it is not clear whether these oscillations are externally driven or generated in situ. We address this question by using observations
      Krishna Prasad, S. et al.

      Fecha de publicación:

      10
      2015
      Número de citas
      47
    • The WEBT campaign on the BL Lac object PG 1553+113 in 2013. An analysis of the enigmatic synchrotron emission
      A multifrequency campaign on the BL Lac object PG 1553+113 was organized by the Whole Earth Blazar Telescope (WEBT) in 2013 April-August, involving 19 optical, two near-IR, and three radio telescopes. The aim was to study the source behaviour at low energies during and around the high-energy observations by the Major Atmospheric Gamma-ray Imaging
      Raiteri, C. M. et al.

      Fecha de publicación:

      11
      2015
      Número de citas
      37
    • On the nature of transverse coronal waves revealed by wavefront dislocations
      Context. Coronal waves are an important aspect of the dynamics of the plasma in the corona. Wavefront dislocations are topological features of most waves in nature and also of magnetohydrodynamic waves. Are there dislocations in coronal waves? Aims: The finding and explanation of dislocations may shed light on the nature and characteristics of the
      López Ariste, A. et al.

      Fecha de publicación:

      7
      2015
      Número de citas
      5
    • Are Tornado-like Magnetic Structures Able to Support Solar Prominence Plasma?
      Recent high-resolution and high-cadence observations have surprisingly suggested that prominence barbs exhibit apparent rotating motions suggestive of a tornado-like structure. Additional evidence has been provided by Doppler measurements. The observations reveal opposite velocities for both hot and cool plasma on the two sides of a prominence barb
      Luna, M. et al.

      Fecha de publicación:

      7
      2015
      Número de citas
      22
    • Where are the solar magnetic poles?
      Regardless of the physical origin of stellar magnetic fields - fossil or dynamo induced - an inclination angle between the magnetic and rotation axes is very often observed. Absence of observational evidence in this direction in the solar case has led to generally assume that its global magnetic field and rotation axes are well aligned. We present
      Collados, M. et al.

      Fecha de publicación:

      10
      2015
      Número de citas
      11
    • Equation of state for solar near-surface convection
      Numerical 3-D radiative hydrodynamical simulations are the main tool for the analysis of the interface between the solar convection zone and the photosphere. The equation of state is one of the necessary ingredients of these simulations. We compare two equations of state that are commonly used, one ideal and one nonideal, and quantify their
      Khomenko, E. et al.

      Fecha de publicación:

      6
      2015
      Número de citas
      4
    • Spatial deconvolution of spectropolarimetric data: an application to quiet Sun magnetic elements
      Context. One of the difficulties in extracting reliable information about the thermodynamical and magnetic properties of solar plasmas from spectropolarimetric observations is the presence of light dispersed inside the instruments, known as stray light. Aims: We aim to analyze quiet Sun observations after the spatial deconvolution of the data. We
      Quintero Noda, C. et al.

      Fecha de publicación:

      7
      2015
      Número de citas
      30
    • Model comparison for the density structure along solar prominence threads
      Context. Quiescent solar prominence fine structures are typically modelled as density enhancements, called threads, which occupy a fraction of a longer magnetic flux tube. This is justified from the spatial distribution of the imaged plasma emission or absorption of prominences at small spatial scales. The profile of the mass density along the
      Arregui, I. et al.

      Fecha de publicación:

      6
      2015
      Número de citas
      11
    • Beyond MHD: modeling and observation of partially ionized solar plasma processes
      The temperature and density conditions in the magnetized photosphere and chromosphere of the Sun lead to a very small degree of atomic ionization. At particular heights, the magnetic field may be strong enough to give rise to a cyclotron frequency larger than the collisional frequency for some species. These circumstances influence the collective
      Khomenko, E.

      Fecha de publicación:

      5
      2015
      Número de citas
      1
    • Variation in sunspot properties between 1999 and 2014
      Aims: We study the variation in the magnetic field strength, area, and continuum intensity of umbrae in solar cycles 23 and 24. Methods: We analyzed a sample of 374 sunspots observed from 1999 until 2014 with the Tenerife Infrared Polarimeter at the German Vacuum Tower Telescope and the Facility InfRared Spectropolarimeter at the Dunn Solar
      Rezaei, R. et al.

      Fecha de publicación:

      6
      2015
      Número de citas
      17
    • Magnetohydrodynamic wave propagation from the subphotosphere to the corona in an arcade-shaped magnetic field with a null point
      Aims: The aim of this work is to study the energy transport by means of Magnetohydrodynamic (MHD) waves propagating in quiet-Sun magnetic topology from layers below the surface to the corona. Upwardly propagating waves find obstacles, such as the equipartition layer with plasma β = 1, the transition region, and null points, and they get transmitted
      Santamaria, I. C. et al.

      Fecha de publicación:

      5
      2015
      Número de citas
      36
    • Estimating the magnetic field strength from magnetograms
      A properly calibrated longitudinal magnetograph is an instrument that measures circular polarization and gives an estimation of the magnetic flux density in each observed resolution element. This usually constitutes a lower bound of the field strength in the resolution element, given that it can be made arbitrarily large as long as it occupies a
      Asensio Ramos, A. et al.

      Fecha de publicación:

      5
      2015
      Número de citas
      2
    • Multiwavelength behaviour of the blazar OJ 248 from radio to γ-rays
      We present an analysis of the multiwavelength behaviour of the blazar OJ 248 at z = 0.939 in the period 2006-2013. We use low-energy data (optical, near-infrared, and radio) obtained by 21 observatories participating in the Gamma-Ray Large Area Space Telescope (GLAST)-AGILE Support Program of the Whole Earth Blazar Telescope, as well as data from
      Carnerero, M. I. et al.

      Fecha de publicación:

      7
      2015
      Número de citas
      34
    • Alfvén wave coupled with flow-driven fluid instability in interpenetrating plasmas
      The Alfvén wave is analyzed in case of one quasineutral plasma propagating with some constant speed v0 through another static quasineutral plasma. A dispersion equation is derived describing the Alfvén wave coupled with the flow driven mode ω = k v 0 and solutions are discussed analytically and numerically. The usual solutions for two oppositely
      Vranjes, J.

      Fecha de publicación:

      5
      2015
      Número de citas
      4
    • Drift wave stabilized by an additional streaming ion or plasma population
      It is shown that the universally unstable kinetic drift wave in an electron-ion plasma can very effectively be suppressed by adding an extra flowing ion (or plasma) population. The effect of the flow of the added ions is essential, their response is of the type (vp h-vf 0) exp[-(vph-vf 0) 2] , where vf 0 is the flow speed and vp h is the phase
      Bashir, M. F. et al.

      Fecha de publicación:

      3
      2015
      Número de citas
      7
    • An open-source, massively parallel code for non-LTE synthesis and inversion of spectral lines and Zeeman-induced Stokes profiles
      With the advent of a new generation of solar telescopes and instrumentation, interpreting chromospheric observations (in particular, spectropolarimetry) requires new, suitable diagnostic tools. This paper describes a new code, NICOLE, that has been designed for Stokes non-LTE radiative transfer, for synthesis and inversion of spectral lines and
      Socas-Navarro, H. et al.

      Fecha de publicación:

      5
      2015
      Número de citas
      151
    • Spectro-Polarimetric Imaging Reveals Helical Magnetic Fields in Solar Prominence Feet
      Solar prominences are clouds of cool plasma levitating above the solar surface and insulated from the million-degree corona by magnetic fields. They form in regions of complex magnetic topology, characterized by non-potential fields, which can evolve abruptly, disintegrating the prominence and ejecting magnetized material into the heliosphere
      Martínez González, M. J. et al.

      Fecha de publicación:

      3
      2015
      Número de citas
      32

    Charlas relacionadas

    No se han encontrado charlas relacionadas.

    Congresos relacionados

    No se han encontrado congresos relacionados.