Shell star variables. Pleione and Gamma Cassiopeiae itself are both variable stars that have intermittent shell episodes where strong shell features appear in the spectrum and the brightness increases or decreases significantly. At other times the shell is not detectable in the spectrum, and even the emission lines may disappear. Shell star A shell star is a star having a spectrum that shows extremely broad absorption lines, plus some very narrow absorption lines. They typically also show some emission lines, usually from the Balmer series but occasionally of other lines. The broad absorption lines are due to rapid rotation of the photosphere,
What is a Masterpiece? confluence of memories and emotions forming a single idea", that it has "a power of recreating traditional forms so that they become expressive of an artist's own epoch and yet keep a relationship to the past". The highest masterpieces are said to be "illustrations of great themes." Clark also implicitly excluded the erotic from considerations of what constituted a masterpiece, based on his perspective that a necessary condition is the balance between sense and form (works that are too sensual are, therefore, unbalanced and not to be categorised at masterpiece level). What is a Masterpiece? What is a Masterpiece? is