Dynamic fibrils in H-alpha and C IV

TL;DR

This study investigates the relationship between chromospheric fibrils observed in H-alpha and transition-region jets seen in C IV, revealing that some fibrils are heated to transition-region temperatures, indicating a connection between chromospheric and transition-region dynamics.

Contribution

It provides the first detailed alignment and comparison of dynamic fibrils in H-alpha with transition-region jets in C IV, demonstrating their physical connection and heating processes.

Findings

Dynamic fibrils appear as absorption features in H-alpha moving from blue to red wing.

Some fibrils also appear as bright features in C IV at their apex.

Fibrils in H-alpha often precede C IV brightening by about half a minute.

Abstract

Aim: To study the interaction of the solar chromosphere with the transition region, in particular active-region jets in the transition region and their relation to chromospheric fibrils. Methods: We carefully align image sequences taken simultaneously in C IV with the Transition Region and Coronal Explorer and in H-alpha with the Swedish 1-m Solar Telescope. We examine the temporal evolution of "dynamic fibrils", i.e., individual short-lived active-region chromospheric jet-like features in H-alpha. Results: All dynamic fibrils appear as absorption features in H-alpha that progress from the blue to the red wing through the line, and often show recurrent behavior. Some of them, but not all, appear also as bright features in C IV which develop at or just beyond the apex of the H-alpha darkening. They tend to best resemble the H-alpha fibril at +700 mA half a minute earlier. Conclusions: Dynamic chromospheric fibrils observed in H-alpha regularly correspond to transition-region jets observed in the ultraviolet. This correspondence suggests that some plasma associated with dynamic fibrils is heated to transition-region temperatures.