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S. M. Díaz Castillo

Publications and source records attributed to S. M. Díaz Castillo.

2 recordsLinked to original sources

Wave excitation by a collapsing granule: insights from IFU observations and high-resolution RMHD simulations

Context. Granular collapse is an ubiquitous process of granular evolution on the solar surface, but it is hard to analyze in sufficient spatial, temporal, and spectral detail. Aims. We analyze the change in physical conditions in the photosphere during a specific granular collapse event and the subsequent atmospheric response. Methods. We contrast a high-resolution radiative magneto-hydrodynamic simulation of a granular collapse performed using the CO5BOLD code with the recent integral field unit observations carried out using the MiHI instrument at the Swedish 1-m Solar Telescope. Results. Our analysis shows that the observed and simulated granular collapse show remarkable similarity. Specifically, they both exhibit the signature of a wave pulse excited in the deep photosphere and visible up to the temperature minimum. This wave is detectable through a blue-wing emission in the observed and synthetic Na i D1 line. We also estimate the acoustic energy flux carried by the wave and analyze its initiation. Conclusions. Combining high-resolution IFU spectropolarimetry and state-of-the-art simulations of the solar lower atmosphere, this study showcases our current capabilities in identifying specific physical processes taking place during the granular collapse and their impact on the atmosphere above.

astro-ph.SR↗

Morphological variations of solar granules in the presence of magnetic fields

Solar granulation consists of dynamic convective plasma cells that rise from the solar interior to the surface. The interaction between these plasma cells and the Sun's magnetic field provides valuable insights into plasma dynamics near the solar surface and how they evolve in the presence of magnetic fields. This study analyses the morphological characteristics of solar convective cells, investigating the relationship between magnetic field properties and granule dynamics - specifically how granule area, shape, and brightness vary under different magnetic field conditions. Observations of the active region NOAA 11768 were taken with the Swedish 1-m Solar Telescope (SST). A segmentation algorithm was applied to continuum intensity images to identify individual granules and determine their sizes, shapes, and mean brightness. The magnetic field vector and line-of-sight velocity were derived from CRISP spectropolarimetric data to investigate their role in shaping granule properties. We find that granular area decreases systematically with increasing magnetic field strength, with the largest granules occurring in non-magnetic regions and a mean granule area of approximately 1.58 arcsec$^2$ (effective diameter of 1.42 arcseconds). Both mean continuum intensity and granule size decrease with stronger fields, confirming the suppression of convective energy transport in magnetised regions. No correlation was found between mean granule brightness and mean up-flow velocity. Highly elongated granules appear in both magnetic and non-magnetic regions, while near-circular granules are exclusive to non-magnetic areas. An alignment between granule major axes and magnetic field azimuth is observed where the horizontal field component is strong, confirming that granules are highly sensitive to magnetic fields, which inhibit the lateral expansion of convective cells.

astro-ph.SR↗