noun
red flame; crimson blaze
Literary or poetic term for a vividly red flame. Not an everyday word for fire.
紅炎が夜空を焦がすように燃え上がった。
A crimson blaze shot up as if scorching the night sky.
noun
solar prominence
Astronomy term for a large, bright feature extending outward from the Sun's surface.
皆既日食のとき、太陽の縁に紅炎が観測された。
During the total solar eclipse, solar prominences were observed at the Sun's edge.
Compound of 紅 (crimson, deep red) and 炎 (flame, blaze). The astronomical sense is a calque from English 'solar prominence', using the same kanji to evoke a reddish flame-like structure on the Sun.