Be star

The infrared excess and the polarization result from the scattering of stellar light in the disk, while the line emission is formed by re-processing stellar ultraviolet light in the gaseous disc.

[2] Some Be stars exhibit spectral features that are interpreted as a detached "shell" of gas surrounding the star, or more accurately a disc or ring.

These shell features are thought to be caused when the disc of gas that is present around many Be stars is aligned edge on to us so that it creates very narrow absorption lines in the spectrum.

Be stars that show variability without clear indication of the mechanism are listed simply as BE in the General Catalogue of Variable Stars.

Some of these are thought to be pulsating stars and are sometimes called Lambda Eridani variables.