The plasma contributing to emission from the Sun between cool chromosphere ($\le 10^4$K) and hot corona ($\ge 10^6$K) has been subjected many different interpretations. Here we look at magnetic structure of this transition region (TR) plasma, based upon implications CLASP2 data an active recently published by Ishikawa et al., earlier IRIS SDO quiet regions. al. found that large areas sunspot pl...

We investigate the structure of a pure photoionization layer in the solar chromosphere on the basis of a one dimensional model in which an incident flux of EUV photons from above ionizes neutral hydrogen assumed to be flowing up with steady subsonic speeds from below. It is useful to analyze the structure equation in the phase plane of the hydrogen density (or velocity) and the ionizing photon ...

Brazilian Solar Spectroscope (BSS), operating in the frequency range of (1000 − 2500) MHz with high time and frequency resolutions, has observed various fine structures showing intensity variations as functions of time and frequency. Here we are reporting radio bursts observed by BSS, from August to October/2001, exhibiting fine structures with total duration of the order of 300 ms, covering a ...

Abstract Acoustic wave heating is believed to contribute significantly the missing energy input required maintain solar chromosphere in its observed state. We studied propagation of waves above acoustic cutoff upper photosphere into with ultraviolet and optical spectral observations interpreted through comparison 3D radiative magnetohydrodynamic Bifrost models constrain contribution from atmosp...

The flare activity of the Sun has been studied for decades, using both space- and ground-based telescopes. former have mainly focused on corona, while latter mostly used to investigate conditions in chromosphere photosphere. Interface Region Imaging Spectrograph (IRIS) instrument served as a gateway between these two cases, given its capability observe quasi-simultaneously transition region, di...

Spectropolarimetric time series data of the primary spot of active region NOAA 9448 were obtained in the Si i 10827 Å line and the He i 10830 Å multiplet with the Tenerife Infrared Polarimeter. Throughout the time series the spectrograph slit was fixed over a region covering umbra, a light bridge, penumbra, and quiet sun. We present speeds of running penumbral waves in the chromosphere, their r...

The solar chromosphere is occupied with a wealth of fine structures referred to by diverse nomenclature. Recent identification of slow-mode magnetoacoustic shocks, excited by p-modes of photospheric oscillations, as plausible drivers of dynamic fibrils and spicules was followed by a surge of observational studies and numerical simulations attempting to reveal the role of chromospheric fine stru...

We present an analytical model for the damping of Alfvén waves in the partially ionized chromosphere. The damping is due to collisions between ions and neutrals. The ionneutral collision frequency in this environment is such that the ion and neutral populations are almost perfectly collisionally coupled, leading the Alfvén wave to behave as if it acts on the whole plasma (i.e. including neutral...