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.
Hayden (given name) but down from No. 52 in 2012 and No. 43 in 2011. Hayden (given name) Hayden is a given name in the English language. The name is variant of the given name "Haydn", which is derived from the surname "Haydn" in honour of composer Joseph Haydn (1732–1809). The surname "Haydn" originated as a respelling of the nickname "Heiden", meaning "". The name is derived from the Middle High German "heiden", and from the Old High German "heidano". The form "Haydn" was generally considered a masculine given name up until the mid 20th century. The popularity of "Hayden" has been influenced