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
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Bright Points in the Quiet Sun as Observed in the Visible and Near-UV by the Balloon-borne Observatory SUNRISE
Bright points (BPs) are manifestations of small magnetic elements in the solar photosphere. Their brightness contrast not only gives insight into the thermal state of the photosphere (and chromosphere) in magnetic elements, but also plays an important role in modulating the solar total and spectral irradiance. Here, we report on simultaneous high
Riethmüller, T. L. et al.Fecha de publicación:
112010 -
Variation in sunspot properties between 1999 and 2011 as observed with the Tenerife Infrared Polarimeter
Aims: We study the variation in the magnetic field strength and the umbral intensity of sunspots during the declining phase of the solar cycle No. 23 and in the beginning of cycle No. 24. Methods: We analyze a sample of 183 sunspots observed from 1999 until 2011 with the Tenerife Infrared Polarimeter (TIP) at the German Vacuum Tower Telescope (VTT)
Rezaei, R. et al.Fecha de publicación:
52012 -
Two-dimensional solar spectropolarimetry with the KIS/IAA Visible Imaging Polarimeter
Context. Spectropolarimetry at high spatial and spectral resolution is a basic tool to characterize the magnetic properties of the solar atmosphere. Aims: We introduce the KIS/IAA Visible Imaging Polarimeter (VIP), a new post-focus instrument that upgrades the TESOS spectrometer at the German Vacuum Tower Telescope (VTT) into a full vector
Beck, C. et al.Fecha de publicación:
92010 -
The signature of chromospheric heating in Ca II H spectra
Context: The heating process that balances the solar chromospheric energy losses has not yet been determined. Conflicting views exist on the source of the energy and the influence of photospheric magnetic fields on chromospheric heating. Aims: We analyze a 1-h time series of cospatial Ca II H intensity spectra and photospheric polarimetric spectra
Beck, C. et al.Fecha de publicación:
22008 -
The magnetic flux of the quiet Sun internetwork as observed with the Tenerife infrared polarimeter
Context: Observations made with the spectropolarimeter onboard the HINODE satellite have detected abundant horizontal magnetic fields in the internetwork quiet Sun. Aims: We compare the results for the horizontal fields obtained at 630 nm with ground-based observations at 1.56 μm, where the sensitivity to magnetic fields is higher than in the
Beck, C. et al.Fecha de publicación:
82009 -
The energy of waves in the photosphere and lower chromosphere. II. Intensity statistics
Context. The energy source powering the solar chromosphere is still undetermined, but leaves its traces in observed intensities. Aims: We investigate the statistics of the intensity distributions as a function of the wavelength for Ca ii H and the Ca ii IR line at 854.2 nm to estimate the energy content in the observed intensity fluctuations
Beck, C. et al.Fecha de publicación:
82012 -
The energy of waves in the photosphere and lower chromosphere. I. Velocity statistics
Context: Acoustic waves are one of the primary suspects besides magnetic fields for the chromospheric heating process to temperatures above radiative equilibrium (RE). Aims: We derived the mechanical wave energy as seen in line-core velocities on disc centre to obtain a measure of mechanical energy flux with height for a comparison with the energy
Beck, C. et al.Fecha de publicación:
112009 -
The Chromospheric Telescope
Aims: We introduce the Chromospheric Telescope (ChroTel) at the Observatorio del Teide in Izaña on Tenerife as a new multi-wavelength imaging telescope for full-disk synoptic observations of the solar chromosphere. We describe the design of the instrument and summarize its performance during the first one and a half years of operation. We present a
Bethge, C. et al.Fecha de publicación:
102011 -
Stray-light contamination and spatial deconvolution of slit-spectrograph observations
Context. Stray light caused by scattering on optical surfaces and in the Earth's atmosphere degrades the spatial resolution of observations. Whereas post-facto reconstruction techniques are common for 2D imaging and spectroscopy, similar options for slit-spectrograph data are rarely applied. Aims: We study the contribution of stray light to the two
Beck, C. et al.Fecha de publicación:
112011 -
Spectroscopy at the solar limb. I. Average off-limb profiles and Doppler shifts of Ca II H
Aims: We present constraints on the thermodynamical structure of the chromosphere from ground-based observations of the Ca ii H line profile near and off the solar limb. Methods: We obtained a slit-spectrograph data set of the Ca ii H line with a high signal-to-noise ratio in a field of view extending 20'' across the limb. We analyzed the spectra
Beck, C. et al.Fecha de publicación:
72011 -
Siphon flow in a cool magnetic loop
Context. Siphon flows that are driven by a gas pressure difference between two photospheric footpoints of different magnetic field strength connected by magnetic field lines are a well-studied phenomenon in theory, but observational evidence is scarce. Aims. We investigate the properties of a structure in the solar chromosphere in an active region
Bethge, C. et al.Fecha de publicación:
12012 -
Reversal-free Ca II H profiles: a challenge for solar chromosphere modeling in quiet inter-network
Aims: We study chromospheric emission to understand the temperature stratification in the solar chromosphere. Methods: We observed the intensity profile of the Ca II H line in a quiet Sun region close to the disk center at the German Vacuum Tower Telescope. We analyze over 105 line profiles from inter-network regions. For comparison with the
Rezaei, R. et al.Fecha de publicación:
62008 -
Multiline Zeeman signatures through line addition
Context: To obtain a significant Zeeman signature in the polarised spectra of a magnetic star, we usually “add” the contributions of numerous spectral lines; the ultimate goal is to recover the spectropolarimetric prints of the magnetic field in these line additions. Aims: Here we want to clarify the meaning of these techniques of line addition; in
Semel, M. et al.Fecha de publicación:
92009 -
Multiline Spectropolarimetry of the Quiet Sun at 5250 and 6302 Å
The reliability of quiet-Sun magnetic field diagnostics based on the Fe I lines at 6302 Å has been questioned by recent work. Here we present the results of a thorough study of high-resolution multiline observations taken with the new spectropolarimeter SPINOR, comprising the 5250 and 6302 Å spectral domains. The observations were analyzed using
Socas-Navarro, H. et al.Fecha de publicación:
22008 -
Multi-layer Study of Wave Propagation in Sunspots
We analyze the propagation of waves in sunspots from the photosphere to the chromosphere using time series of co-spatial Ca II H intensity spectra (including its line blends) and polarimetric spectra of Si I λ10,827 and the He I λ10,830 multiplet. From the Doppler shifts of these lines we retrieve the variation of the velocity along the line of
Felipe, T. et al.Fecha de publicación:
102010 -
Magneto-acoustic waves in sunspots from observations and numerical simulations
We study the propagation of waves from the photosphere to the chromosphere of sunspots. From time series of cospatial Ca II H (including its line blends) intensity spectra and polarimetric spectra of Si I λ 1082.7 nm and He I λ 1083.0 nm we retrieve the line-of-sight velocity at several heights. The analysis of the phase difference and
Felipe, T. et al.Fecha de publicación:
12011 -
Magnetic loop emergence within a granule
Aims: We investigate the temporal evolution of magnetic flux emerging within a granule in the quiet-Sun internetwork at disk center. Methods: We combined IR spectropolarimetry of high angular resolution performed in two Fe i lines at 1565 nm with speckle-reconstructed G-band imaging. We determined the magnetic field parameters by a LTE inversion of
Gömöry, P. et al.Fecha de publicación:
22010 -
Linear wavelength correlation matrices of photospheric and chromospheric spectral lines. I. Observations vs. modeling
Context. The process that heats the solar chromosphere is a difficult target for observational studies because the assumption of local thermal equilibrium (LTE) is not valid in the upper solar atmosphere, which complicates the analysis of spectra. Aims: We investigate the linear correlation coefficient between the intensities at different
Beck, C. A. R. et al.Fecha de publicación:
22010 -
Internetwork magnetic field distribution from simultaneous 1.56 μm and 630 nm observations
Aims:We study the contradictory magnetic field strength distributions retrieved from independent analyses of spectropolarimetric observations in the near-infrared (1.56 μm) and in the visible (630 nm) spectral ranges in internetwork regions. Methods: To solve this apparent controversy, we present simultaneous and co-spatial 1.56 μm and 630 nm
Martínez González, M. J. et al.Fecha de publicación:
12008 -
Error propagation in polarimetric demodulation
The polarization analysis of light is typically carried out using modulation schemes. The light of an unknown polarization state is passed through a set of known modulation optics, and a detector is used to measure the total intensity passing the system. The modulation optics is modified several times, and, with the aid of several such measurements
Asensio Ramos, A. et al.Fecha de publicación:
52008
