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? What is a Masterpiece? What is a Masterpiece? is a 1979 non-fiction book by British historian Kenneth Clark. It is a transcribed version of the Walter Neurath memorial lectures given by Clark. The work, initially released on 1 January 1979, received a Thames & Hudson republication on 1 May 1992. Kenneth Clark had already achieved fame with a series of popular books while also serving as, from 1969 on, the writer, producer and presenter of the BBC programme, "Civilisation", a pioneering television documentary series. The prestigious series earned a Peabody Award as well as general commercial success. In the work,