Subvenciones relacionadas:
General
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
- Estructura y evolución del campo magnético en manchas solares.
- Estructura y evolución del campo magnético en el Sol en calma.
- Estructura y evolución del campo magnético en la cromosfera y en estructuras cromosféricas (protuberancias, espículas,...)
- Estructura y evolución del campo magnético en bucles coronales.
- Estructura y evolución del campo magnético global del Sol. Estudios del ciclo de actividad magnética.
- Estudio empírico de la propagación de ondas magnetohidrodinámicas en el seno de estructuras magnéticas.
- Estudio empírico de mecanismos relacionados con el calentamiento de las capas externas del Sol.
- Estudio empírico de la influencia de la ionización parcial en la dinamica de la atmosfera solar.
- Implicación en el proyecto del Telescopio Solar Europeo.
Magnetismo estelar
- Desarrollo de métodos numéricos para el diagnóstico del campo magnético estelar, tanto en la superficie como en la cromosfera.
- Estudio del magnetismo en protuberancias estelares.
- Impacto del campo magnético en las últimas fases de la evolución estelar.
Miembros
Resultados
- 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).
- 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).
Actividad científica
Publicaciones relacionadas
-
Learning to do multiframe wavefront sensing unsupervised: Applications to blind deconvolutionContext. Observations from ground-based telescopes are severely perturbed by the presence of the Earth's atmosphere. The use of adaptive optics techniques has allowed us to partly overcome this limitation. However, image-selection or post-facto image-reconstruction methods applied to bursts of short-exposure images are routinely needed to reach theAsensio Ramos, A. et al.
Fecha de publicación:
22021 -
Two-fluid simulations of Rayleigh-Taylor instability in a magnetized solar prominence thread. I. Effects of prominence magnetization and mass loadingSolar prominences are formed by partially ionized plasma with inter-particle collision frequencies, which generally warrant magnetohydrodynamic treatment. In this work, we explore the dynamical impacts and observable signatures of two-fluid effects in the parameter regimes when ion-neutral collisions do not fully couple the neutral and chargedPopescu Braileanu, B. et al.
Fecha de publicación:
22021 -
Planet cartography with neural learned regularizationAims: Finding potential life harboring exo-Earths with future telescopes is one of the aims of exoplanetary science. Detecting signatures of life in exoplanets will likely first be accomplished by determining the bulk composition of the planetary atmosphere via reflected or transmitted spectroscopy. However, a complete understanding of theAsensio Ramos, A. et al.
Fecha de publicación:
22021 -
Downflowing umbral flashes as evidence of standing waves in sunspot umbraeContext. Umbral flashes are sudden brightenings commonly visible in the core of some chromospheric lines. Theoretical and numerical modeling suggests that they are produced by the propagation of shock waves. According to these models and early observations, umbral flashes are associated with upflows. However, recent studies have reported umbralFelipe, T. et al.
Fecha de publicación:
12021 -
Signatures of sunspot oscillations and the case for chromospheric resonancesSunspots host a large variety of oscillatory phenomena, whose properties depend on the nature of the wave modes and the magnetic and thermodynamic structure of the spot. Umbral chromospheric oscillations exhibit significant differences compared to their photospheric counterparts. They show an enhanced power and a shorter dominant period, from wavesFelipe, Tobías
Fecha de publicación:
02021 -
Accurately constraining velocity information from spectral imaging observations using machine learning techniquesDetermining accurate plasma Doppler (line-of-sight) velocities from spectroscopic measurements is a challenging endeavour, especially when weak chromospheric absorption lines are often rapidly evolving and, hence, contain multiple spectral components in their constituent line profiles. Here, we present a novel method that employs machine learningMacBride, Conor D. et al.
Fecha de publicación:
22021 -
Coronal Heating by MHD WavesThe heating of the solar chromosphere and corona to the observed high temperatures, imply the presence of ongoing heating that balances the strong radiative and thermal conduction losses expected in the solar atmosphere. It has been theorized for decades that the required heating mechanisms of the chromospheric and coronal parts of the activeVan Doorsselaere, Tom et al.
Fecha de publicación:
122020 -
Spatially resolved measurements of the solar photospheric oxygen abundanceAims: We report the results of a novel determination of the solar oxygen abundance using spatially resolved observations and inversions. We seek to derive the photospheric solar oxygen abundance with a method that is robust against uncertainties in the model atmosphere. Methods: We use observations with spatial resolution obtained at the VacuumCubas Armas, M. et al.
Fecha de publicación:
112020 -
Joint action of Hall and ambipolar effects in 3D magneto-convection simulations of the quiet Sun. I. Dissipation and generation of wavesThe partial ionization of the solar plasma causes several nonideal effects such as the ambipolar diffusion, the Hall effect, and the Biermann battery effect. Here we report on the first three-dimensional realistic simulations of solar local dynamo where all three effects were taken into account. The simulations started with a snapshot of alreadyGonzález-Morales, P. A. et al.
Fecha de publicación:
102020 -
Ubiquitous hundred-Gauss magnetic fields in solar spiculesAims: We aim to study the magnetic field in solar spicules using high-resolution spectropolarimetric observations in the Ca II 8542 Å line obtained with the Swedish 1-m Solar Telescope. Methods: The equations that result from the application of the weak field approximation (WFA) to the radiative transfer equations were used to infer the line-ofKriginsky, M. et al.
Fecha de publicación:
102020 -
The Polarimetric and Helioseismic Imager on Solar OrbiterAims: This paper describes the Polarimetric and Helioseismic Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and helioseismology instrument to observe the Sun from outside the Sun-Earth line. It is the key instrument meant to address the top-level science question: How does the solar dynamo work and drive connections betweenSolanki, S. K. et al.
Fecha de publicación:
102020 -
Resonant absorption: Transformation of compressive motions into vortical motionsThis paper investigates the changes in spatial properties when magnetohydrodynamic (MHD) waves undergo resonant damping in the Alfvén continuum. The analysis is carried out for a 1D cylindrical pressure-less plasma with a straight magnetic field. The effect of the damping on the spatial wave variables is determined by using complex frequencies thatGoossens, M. et al.
Fecha de publicación:
92020 -
Chromospheric Resonances above Sunspots and Potential Seismological ApplicationsOscillations in sunspot umbrae exhibit remarkable differences between the photosphere and chromosphere. We evaluate two competing scenarios proposed for explaining those observations: a chromospheric resonant cavity and waves traveling from the photosphere to upper atmospheric layers. We have employed numerical simulations to analyze theFelipe, Tobias et al.
Fecha de publicación:
92020 -
A chromospheric resonance cavity in a sunspot mapped with seismologySunspots are intense collections of magnetic fields that pierce through the Sun's photosphere, with their signatures extending upwards into the outermost extremities of the solar corona 1. Cutting-edge observations and simulations are providing insights into the underlying wave generation 2, configuration 3,4 and damping 5 mechanisms found inJess, David B. et al.
Fecha de publicación:
12020 -
Quantifying the evidence for resonant damping of coronal waves with foot-point wave power asymmetryWe use Coronal Multi-channel Polarimeter (CoMP) observations of propagating waves in the solar corona together with Bayesian analysis to assess the evidence of models with resonant damping and foot-point wave power asymmetries. We considered two nested models: a reduced and a larger model. The reduced model considers resonant damping as the soleMontes-Solís, M. et al.
Fecha de publicación:
82020 -
Determining the dynamics and magnetic fields in He I 10830 Å during a solar filament eruptionAims: We investigate the dynamics and magnetic properties of the plasma, including the line-of-sight velocity (LOS) and optical depth, as well as the vertical and horizontal magnetic fields, belonging to an erupted solar filament. Methods: The filament eruption was observed with the GREGOR Infrared Spectrograph at the 1.5-meter GREGOR telescope onKuckein, C. et al.
Fecha de publicación:
82020 -
Numerical determination of the cutoff frequency in solar modelsContext. In stratified atmospheres, acoustic waves can only propagate if their frequency is higher than the cutoff value. The determination of the cutoff frequency is fundamental for several topics in solar physics, such as evaluating the contribution of the acoustic waves to the chromospheric heating or the application of seismic techniquesFelipe, T. et al.
Fecha de publicación:
82020 -
Chromospheric Magnetic Field: A Comparison of He I 10830 Å Observations with Nonlinear Force-free Field ExtrapolationThe nonlinear force-free field (NLFFF) modeling has been extensively used to infer the three-dimensional magnetic field in the solar corona. One of the assumptions in the NLFFF extrapolation is that the plasma beta is low, but this condition is considered to be incorrect in the photosphere. We examine direct measurements of the chromosphericKawabata, Yusuke et al.
Fecha de publicación:
72020 -
On the Magnetic Nature of an Exploding Granule as Revealed by Sunrise/IMaXWe study the photospheric evolution of an exploding granule observed in the quiet Sun at high spatial (∼0"3) and temporal (31.5 s) resolution by the imaging magnetograph Sunrise/IMaX in 2009 June. These observations show that the exploding granule is cospatial to a magnetic flux emergence event occurring at mesogranular scale (up to ∼12 Mm 2 area)Guglielmino, Salvo L. et al.
Fecha de publicación:
62020 -
Numerical simulations of large-amplitude oscillations in flux rope solar prominencesContext. Large-amplitude oscillations (LAOs) of solar prominences are a very spectacular, but poorly understood, phenomena. These motions have amplitudes larger than 10 km s -1 and can be triggered by the external perturbations such as Moreton or EIT waves. Aims: Our aim is to analyze the properties of LAOs using realistic prominence models and theLiakh, V. et al.
Fecha de publicación:
52020