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.
Luca (given name) the Balkans with the name sharing the same origin. Luca is also a Hungarian and Croatian female given name, but pronounced differently as "LOO-tsah" the equivalent of the English name Lucy. Luca (given name) Luca (also spelt Louca, Luka, Louka, Lucca) is a given name used predominantly for males, mainly in Latin America, Italy, Spain, Portugal, Romania, Russia, Serbia, Slovenia, Croatia, Bulgaria, Greece, Georgia and Armenia. It is derived from the Latin name Lucas, which itself is derived from the Latin word "lux" (light). It may also come from the Latin word "lucus" meaning "sacred wood" (a cognate of lucere).