The height of H? flare emitting region

Abstract

Direct and clear observational evidence which can determine the height of an Hα flare emitting region is demonstrated. There have been many attempts to study the vertical structure of the flare with observations of the so-called limb flare. In many cases, however, they can be identified as either flare-associated active prominences, surges or post flare loops. In this paper we show that the top of an Hα flare emitting region is much lower than that of the normal Hα chromosphere, and that Hα flares on the solar limb can not be correctly observed in Hα line center.