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.
Alan (given name) century, where it was about even with "Simon", and more numerous than "Henry". Early occurrences of the name in British records include: "Alanus" in 1066 (in the "Domesday Book"); and "Alain" in 1183. The name became popular in Scotland in part through the Stewarts. This family descends from Alan fitz Flaad, an Anglo-Breton knight, who possessed lands in what is modern day Shropshire, England. Alan (given name) Alan is a masculine given name in the English language. There are numerous differing etymologies attributed to the name. The name was first introduced into England by Bretons who took part in the