A Be star is a B-type star with prominent emission lines in its spectrum. Other observational characteristics include optical linear polarization and often infrared radiation that is much stronger than in ordinary B-class stars. In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... This article treats polarization in electrodynamics. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ...

All the observational characteristics are explained with a strong, asymmetric stellar wind from the star. Often the wind forms a circumstellar disk. The strong emission lines and infrared radiation come from the wind, and scattering of the stellar light from the disk produces the polarization. A solar wind is a stream of particles (mostly high-energy protons ~ 500 keV) which are ejected from the upper atmosphere of a star (in the case of a star other than the Earths Sun, it may be called a stellar wind instead). ... In particle physics, scattering is a class of phenomena by which particles are deflected by collisions with other particles. ...