Shell star 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, the emission lines from an equatorial disk, and the narrow absorption lines are produced when the disc is seen nearly edge-on. Shell stars have spectral types O7.5 to F5, with rotation velocities of 200–300 km/s, not far from the point when the rotational acceleration would disrupt the star.
Craig (given name) Craig (given name) Craig is a Scottish, Irish & Welsh masculine given name, all variations derive from the same Celtic branch. The name has two origins. In some cases it can originate from a nickname, derived from the Scottish Gaelic word "creag", meaning "rock," similar to Peter. In other cases, the given name originates from the Scottish surname "Craig", which is also derived from the same Scottish Gaelic word. Cognate forms of "creag" include the Irish "creig", Manx "creg", and Welsh "craig". The English word "crag" also shares an origin with these Celtic words. The given name "Craig" is popular