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

    • An active region filament studied simultaneously in the chromosphere and photosphere. I. Magnetic structure

      Aims: A thorough multiwavelength, multiheight study of the vector magnetic field in a compact active region filament (NOAA 10781) on 2005 July 3 and 5 is presented. We suggest an evolutionary scenario for this filament. Methods: Two different inversion codes were used to analyze the full Stokes vectors acquired with the Tenerife Infrared

      Kuckein, C. et al.

      Fecha de publicación:

      3
      2012
      Número de citas
      88
    • Venus transit 2004: Illustrating the capability of exoplanet transmission spectroscopy

      The transit of Venus in 2004 offered the rare possibility to remotely sense a well-known planetary atmosphere using ground-based absorption spectroscopy. Transmission spectra of Venus' atmosphere were obtained in the near infrared using the Vacuum Tower Telescope (VTT) in Tenerife. Since the instrument was designed to measure the very bright

      Hedelt, P. et al.

      Fecha de publicación:

      9
      2011
      Número de citas
      19
    • Twist, Writhe, and Helicity in the Inner Penumbra of a Sunspot

      The aim of this work is the determination of the twist, writhe, and self-magnetic helicity of penumbral filaments located in an inner sunspot penumbra. For this purpose, we inverted data taken with the spectropolarimeter on board Hinode with the SIR (Stokes Inversion based on Response function) code. For the construction of a three-dimensional

      Ruiz-Cobo, B. et al.

      Fecha de publicación:

      2
      2012
      Número de citas
      8
    • Theoretical Modeling of Propagation of Magnetoacoustic Waves in Magnetic Regions Below Sunspots

      We use two-dimensional numerical simulations and eikonal approximation to study properties of magnetohydrodynamic (MHD) waves traveling below the solar surface through the magnetic structure of sunspots. We consider a series of magnetostatic models of sunspots of different magnetic field strengths, from 10 Mm below the photosphere to the low

      Khomenko, E. et al.

      Fecha de publicación:

      3
      2009
      Número de citas
      43
    • The Electrical Current Density Vector in the Inner Penumbra of a Sunspot

      We determine the entire electrical current density vector in a geometrical three-dimensional volume of the inner penumbra of a sunspot from an inversion of spectropolarimetric data obtained with Hinode/SP. Significant currents are seen to wrap around the hotter, more elevated regions with lower and more horizontal magnetic fields that harbor strong

      Puschmann, K. G. et al.

      Fecha de publicación:

      9
      2010
      Número de citas
      21
    • Supersonic Continuation of the Evershed Flow Outside a Sunspot as Observed with Hinode

      We report on the discovery of mostly horizontal field channels just outside sunspot penumbrae (in the so-called "moat" region) that are seen to sustain supersonic flows (line-of-sight component of 6 km s-1). The spectral signature of these supersonic flows corresponds to circular polarization profiles with an additional, satellite, third lobe of

      Martínez Pillet, V. et al.

      Fecha de publicación:

      8
      2009
      Número de citas
      15
    • Sunspot seismic halos generated by fast MHD wave refraction

      Aims: We suggest an explanation for the high-frequency power excess surrounding active regions known as seismic halos. Methods: We use numerical simulations of magneto-acoustic wave propagation in a magnetostatic sunspot model. Results: We propose that seismic halos can be caused by the additional energy injected by high-frequency fast mode waves

      Khomenko, E. et al.

      Fecha de publicación:

      11
      2009
      Número de citas
      41
    • Preliminary results on the contribution of the convection motions to the Doppler velocity signal

      This investigation aims to study the correlation of the solar background with atmosphere. We used high resolution observations of the NaDl spectral line. In fact the large span in formation heights of this spectral line allowed us to infer the signal from photosphere to chromosphere. We analyzed the data by applying the SIR code (Stokes Inversion

      Simoniello, R. et al.

      Fecha de publicación:

      10
      2008
      Número de citas
      0
    • Nonlinear Numerical Simulations of Magneto-Acoustic Wave Propagation in Small-Scale Flux Tubes

      We present results of nonlinear, two-dimensional, numerical simulations of magneto-acoustic wave propagation in the photosphere and chromosphere of small-scale flux tubes with internal structure. Waves with realistic periods of three to five minutes are studied, after horizontal and vertical oscillatory perturbations are applied to the equilibrium

      Khomenko, E. et al.

      Fecha de publicación:

      9
      2008
      Número de citas
      89
    • Magnetohydrostatic Sunspot Models from Deep Subphotospheric to Chromospheric Layers

      In order to understand the influence of magnetic fields on the propagation properties of waves, as derived from different local helioseismology techniques, forward modeling of waves is required. Such calculations need a model in magnetohydrostatic equilibrium as an initial atmosphere through which to propagate oscillations. We provide a method to

      Khomenko, E. et al.

      Fecha de publicación:

      12
      2008
      Número de citas
      37
    • Magnetoacoustic Wave Energy from Numerical Simulations of an Observed Sunspot Umbra

      We aim at reproducing the height dependence of sunspot wave signatures obtained from spectropolarimetric observations through three-dimensional MHD numerical simulations. A magnetostatic sunspot model based on the properties of the observed sunspot is constructed and perturbed at the photosphere, introducing the fluctuations measured with the Si I

      Felipe, T. et al.

      Fecha de publicación:

      7
      2011
      Número de citas
      33
    • Magneto-acoustic Waves in Sunspots: First Results From a New Three-dimensional Nonlinear Magnetohydrodynamic Code

      Waves observed in the photosphere and chromosphere of sunspots show complex dynamics and spatial patterns. The interpretation of high-resolution sunspot wave observations requires modeling of three-dimensional (3D) nonlinear wave propagation and mode transformation in the sunspot upper layers in realistic spot model atmospheres. Here, we present

      Felipe, T. et al.

      Fecha de publicación:

      8
      2010
      Número de citas
      102
    • Heating of the Magnetized Solar Chromosphere by Partial Ionization Effects

      In this paper, we study the heating of the magnetized solar chromosphere induced by the large fraction of neutral atoms present in this layer. The presence of neutrals, together with the decrease with height of the collisional coupling, leads to deviations from the classical magnetohydrodynamic behavior of the chromospheric plasma. A relative net

      Khomenko, E. et al.

      Fecha de publicación:

      3
      2012
      Número de citas
      136
    • Heat transfer in sunspot penumbrae. Origin of dark-cored penumbral filaments

      Context: Observations at 0.1 arcsec have revealed the existence of dark cores in the bright filaments of sunspot penumbrae. Expectations are high that such dark-cored filaments are the basic building blocks of the penumbra, but their nature remains unknown. Aims: We investigate the origin of dark cores in penumbral filaments and the surplus

      Ruiz Cobo, B. et al.

      Fecha de publicación:

      9
      2008
      Número de citas
      39
    • GREGOR solar telescope: Design and status

      The integration and verification phase of the GREGOR telescope reached an important milestone with the installation of the interim 1 m SolarLite primary mirror. This was the first time that the entire light path had seen sunlight. Since then extensive testing of the telescope and its subsystems has been carried out. The integration and verification

      Volkmer, R. et al.

      Fecha de publicación:

      6
      2010
      Número de citas
      19
    • European Solar Telescope: Progress status

      In this paper, the present status of the development of the design of the European Solar Telescope is described. The telescope is devised to have the best possible angular resolution and polarimetric performance, maximizing the throughput of the whole system. To that aim, adaptive optics and multi-conjugate adaptive optics are integrated in the

      Collados, M. et al.

      Fecha de publicación:

      6
      2010
      Número de citas
      59
    • A Geometrical Height Scale for Sunspot Penumbrae

      Inversions of spectropolarimetric observations of penumbral filaments deliver the stratification of different physical quantities in an optical depth scale. However, without establishing a geometrical height scale, their three-dimensional geometrical structure cannot be derived. This is crucial in understanding the correct spatial variation of

      Puschmann, K. G. et al.

      Fecha de publicación:

      9
      2010
      Número de citas
      42
    • Wave Propagation and Shock Formation in Different Magnetic Structures

      Velocity oscillations "measured" simultaneously at the photosphere and the chromosphere—from time series of spectropolarimetric data in the 10830 Å region—of different solar magnetic features allow us to study the properties of wave propagation as a function of the magnetic flux of the structure (i.e., two different-sized sunspots, a tiny pore, and

      Centeno, R. et al.

      Fecha de publicación:

      2
      2009
      Número de citas
      64
    • The Influence of Coronal EUV Irradiance on the Emission in the He I 10830 Å and D3 Multiplets

      Two of the most attractive spectral windows for spectropolarimetric investigations of the physical properties of the plasma structures in the solar chromosphere and corona are the ones provided by the spectral lines of the He I 10830 and 5876 Å (or D3) multiplets, whose polarization signals are sensitive to the Hanle and Zeeman effects. However, in

      Centeno, R. et al.

      Fecha de publicación:

      4
      2008
      Número de citas
      61
    • Solar magnetism eXplorer (SolmeX). Exploring the magnetic field in the upper atmosphere of our closest star

      The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona—that can also affect life on

      Peter, Hardi et al.

      Fecha de publicación:

      4
      2012
      Número de citas
      29

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