The Structure and Dynamics of the Upper Chromosphere and Lower Transition Region as Revealed by the Subarcsecond VAULT Observations

Abstract

The Very high Angular resolution ULtraviolet Telescope (VAULT) is a sounding rocket payload built to study the crucial interface between the solar chromosphere and the corona by observing the strongest line in the solar spectrum, the Ly α line at 1216 Å. In two flights, VAULT succeeded in obtaining the first ever subarcsecond ( 0.5\hbox{$^''$} ) images of this region with high sensitivity and cadence. Detailed analyses of those observations contributed significantly to new ideas about the nature of the transition region. Here, we present a broad overview of the Ly α atmosphere as revealed by the VAULT observations and bring together past results and new analyses from the second VAULT flight to create a synthesis of our current knowledge of the high-resolution Ly α Sun. We hope that this work will serve as a good reference for the design of upcoming Ly α telescopes and observing plans.