Related papers: Does a Non-Magnetic Solar Chromosphere Exist?
A proposed mechanism for solar chromospheric heating is that magnetohydrodynamic waves propagate upward along magnetic field lines and dissipate their energy in the chromosphere. In particular, compressible magneto-acoustic waves may…
We present theoretical models of chromospheric heating for 55 Cancri, an orange dwarf of relatively low activity. Self-consistent, nonlinear and time-dependent ab-initio numerical computations are pursued encompassing the generation,…
The overall structure and the fine structure of the solar photosphere outside active regions are largely understood, except possibly important roles of a turbulent near-surface dynamo at its bottom, internal gravity waves at its top, and…
Coupling between the photosphere, chromosphere and corona in the quiet Sun (QS) is governed by a complex interplay between magnetic structuring, heating, mass loading, and radiative cooling. Constraining how this balance responds to…
We investigate the thermal response of the atmosphere of a solar-type star to an electron beam injected from a hot Jupiter by performing a 1-dimensional magnetohydrodynamic numerical experiment with non-linear wave dissipation, radiative…
Atmospheric electrification is not a purely terrestrial phenomenon: all Solar System planetary atmospheres become slightly electrified by cosmic ray ionisation. There is evidence for lightning on Jupiter, Saturn, Uranus and Neptune, and it…
Solar photosphere and chromosphere are composed of weakly ionized plasma for which collisional coupling decreases with height. This implies a breakdown of some hypotheses underlying magnetohydrodynamics at low altitudes and gives rise to…
Magnetic waves are a relevant component in the dynamics of the solar atmosphere. Their significance has increased because of their potential as a remote diagnostic tool and their presumed contribution to plasma heating processes. We discuss…
The corona is a structure possessed by stars, including the sun. The abnormal heating of the solar corona and chromosphere is one of the greatest mysteries in modern astronomy. While state-of-the-art observations have identified some…
The outer solar atmosphere, the corona, contains plasma at temperatures of more than a million K, more than 100 times hotter that solar surface. How this gas is heated is a fundamental question tightly interwoven with the structure of the…
Context. The origin of the heating of the solar atmosphere is still an unsolved problem. As the photosphere and chromosphere radiate more energy than the solar corona, it is challenging but important to reveal all the mechanisms that…
Recent observational and numerical studies show a variety of thermal structures in the solar chromosphere. Given that the thermal interplay across the transition region is a key to coronal heating, it is worth investigating how different…
Using high-resolution numerical simulations we investigate the plasma heating driven by periodic two-fluid acoustic waves that originate at the bottom of the photosphere and propagate into the gravitationally stratified and partially…
The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous. To a large extent,…
I first review trends in current solar spectrometry and then concentrate on comparing various spectroscopic diagnostics of the solar chromosphere. Some are actually not at all chromospheric but just photospheric or clapotispheric and do not…
The atmosphere of the Sun is characterized by a complex interplay of competing physical processes: convection, radiation, conduction, and magnetic fields. The most obvious imprint of the solar convection and its overshooting in the low…
This paper presents an analysis of three-dimensional vector currents and temperatures observed in a sunspot from the photosphere to the chromosphere, spanning a range of heights of approximately 1500 km. With this unique dataset, based on…
Magnetohydrodynamic simulations of fully convective, rotating spheres with volume heating near the center and cooling at the surface are presented. The dynamo-generated magnetic field saturates at equipartition field strength near the…
The sun's chromosphere is a highly dynamic, partially-ionized region where spicules (hot jets of plasma) form. Here we present a two-fluid MHD model to study the chromosphere, which includes ion-neutral interaction and frictional heating.…
The relationship between observed structures in the solar atmosphere and the magnetic fields threading them is known only for the solar photosphere, even then imprecisely. We suggest that some of the fine structure in the more tenuous…