The Sun is not alone in hosting a chromosphere: virtually all convective stars (Ftypes and later) possess them. Properties can vary wildly from object to object. Historically, three key systemic behaviors were recognized. First is the strong preference of chromospheres for the cool half of the H–R diagram. Second is the so-called rotation-age-activity connection (“Skumanich law”). Third is the ...

We consider propagation of waves in a stratified non-isothermal magnetic atmosphere. The situation of interest corresponds to waves in the outer solar (chromosphere and corona) and other stellar atmospheres. The waves are simulated by using a high-resolution, well-balanced finite volume based massively parallel code termed SURYA. Numerical experiments in both two and three space dimensions invo...

In this paper a novel mechanism is proposed for the generation of Hα impact polarization observed during some solar flares. Rather than being generated by the primary particle beams transporting energy from the chromosphere to the corona, we suggest that following heating, the solar chromosphere evaporates in a fragmented manner, and that impact excitations in the regions of interaction of hot ...

Recently, we correlated the inferred structure of the solar chromospheric plasma topography with solar wind velocity and composition data measured at 1 AU. We now offer a physical justification of these relationships and present initial results of a empirical prediction model based on them. While still limited by the fundamentally complex physics behind the origins of the solar wind and how its...

We provide a new interpretation of ultraviolet transition region emission line widths observed by the SUMER instrument on the Solar and Heliospheric Observatory (SOHO). This investigation is prompted by observations of the chromosphere at unprecedented spatial and temporal resolution from the Solar Optical Telescope (SOT) on Hinode revealing that all chromospheric structures above the limb disp...

Ca II H emission is a well-known indicator of magnetic activity in the Sun and other stars. It is also viewed as an important signature of chromospheric heating. However, the Ca II H line has not been used as a diagnostic of magnetic flux emergence from the solar interior. Here we report on Hinode observations of chromospheric Ca II H brightenings associated with a repeated, small-scale flux em...