Solar magnetic fields are essential ingredients for the energetics and dynamics of the lower solar atmosphere. After emergence, they continually interact with convective flows and with each other. The resulting field line braiding is believed to trigger magnetic reconnection in the chromosphere and above, generating a wide variety of features and contributing to atmospheric heating, both...
In this talk I will look at the scales at which photospheric motions generate waves and changes in the magnetic field topology. I will then discuss how these scales change throughout the solar atmosphere.
Recent observational studies on abundances reveal the need to expand models by considering different fluids and/or species to be constrained with these observations and interpret them. Similarly, radiative MHD models fail to reproduce observations of the coldest parts of the chromosphere and some properties of the Mg II profiles. Mg II is formed where interactions between multiple ionized and...
Solar chromosphere has been at the focus of solar physics studies for decades, but its heating mechanisms are still unknown. Chromospheric plasma is strongly stratified, weakly ionized and not completely collision coupled. In this talk I will overview our recent results of the modeling of solar chromosphere, comparing a more standard single-fluid approach and a more novel multi-fluid approach....
Our understanding of magnetic reconnection (MR) under chromospheric conditions remains limited. Recent observations have demonstrated the important role of ion-neutral interactions in the dynamics of the chromosphere. Furthermore, the comparison between spectral profiles and synthetic observations of reconnections suggest that single-fluid MHD approaches appear to be inconsistent with...
Recent observations performed by space missions (SDO, Hinode) prove the existence of mini-filament eruptions within the solar chromosphere that could be connected to the formation of chromospheric jets and spicules. The growth of the helical kink instability within these structures is responsible of the onset of magnetic reconnection and lead to explosive events occurring ubiquitously in the...
The chromospheric heating terms cannot be inferred directly from observational datasets. Furthermore, even estimating the thermodynamical state of the plasma usually involves complex NLTE inversion calculations. Therefore, it has been very difficult to quantify in which proportion different heating mechanisms could be operating at different locations of the chromosphere.
One of the most...
The MURaM radiation-magnetohydrodynamics code has long been applied to simulate near-surface magnetoconvection, ranging from quiet sun conditions to complex active regions. The code includes the physics required to treat the convection zone, and the solar atmosphere from the photosphere to the corona. Until now, these simulations have been limited to a local-thermodynamic equilibrium treatment...
This study presents a comparison of the high frequency wave power found in
3D numerical MHD models of the solar atmosphere (Bifrost and MURaM)
with real observations of chromospheric lines. We
also discuss the systematics originating from using different
models to calculate the acoustic wave flux in the solar chromosphere.
In particular, we synthesize from the MHD models spectral lines...
The chromosphere is a very dynamic part of the solar atmosphere. With short time scales and small spatial scales at which fundamental physical processes are taking place, it is a challenge to get a clear observational view of the chromosphere. The CRISP and CHROMIS tunable filter instruments at the Swedish 1-m Solar Telescope (SST) on La Palma are capable of fast wavelength sampling while...
Recent magnetohydrodynamic models show that many of the chromospheric features and their dynamics can be reproduced to some degree. The models demonstrate that the overall appearance of synthetic chromosphere depends mostly on the field configuration and the treatment of the small-scale dynamics. In this talk, the properties of these models are presented, as well as their comparison to...
Nowadays, solar spectra are routinely analyzed to understand the physical mechanisms that trigger different physical phenomena. These spectral lines are modeled using approaches of increasing complexity, ranging from a simple Gaussian model to complex non-LTE radiative transfer calculations. In practice, these data are also affected by telescope degradation, may include some instrumental...
Recent observations revealed loop-like structures at very small scales visible in observables that sample transition region (TR) and coronal temperatures. Their formation remains unclear.
We study an example of a bipolar system in realistic magnetohydrodynamic simulations and forward synthesis of spectral lines to investigate how these features occur.
Computations are done using the...
The solar corona is continuously studied through observations and numerical modelling due to its extreme temperatures. One of the prime candidates in understanding these temperatures is nanoflares, which are small-scale events associated with magnetic reconnection in the solar atmosphere. Observations of small-scale events with nanoflare energies are rare because signatures from non-thermal...
