A Model for the "filaments" in the Cygnus Loop

Abstract

Further spectrophotometric observations have been made of four "filaments," and in particular detail of one "filament," in the Cygnus Loop. The Balmer decrement for all of the "filaments" studied is 2.65, or radiative for case B The temperatures obtained from the line ratios for [0 iii] and [N ii] indicate that there is a stratification within individual "filaments" Collisional ionization may well be important in the high-temperature portions of the "filaments," but high-temperature thermal radiation produces the ionization of the cooler parts of the "filaments "The so-called "filaments" are probably not filaments but irregular sheets produced by the collision of the advancing shock front with the clouds of the interstellar medium, seen edge on.