A Herbig AeBe star is an A-type star or B-type star with Balmer series emission lines, excess infrared due to surrounding dust. Depending upon its spectral class, it is more specifically termed a Herbig Ae star (HAe) or Herbig Be star (HBe). Their luminosity is high for their spectral class. They were first described by George Herbig in 1960. Many are highly variable, and many have calcium emission lines. They are considered to be pre-main-sequence stars (PMSs) more massive than T-Tauri stars (TTSs), i.e., 2 solar masses or more, but a PMS above about 8 solar masses would reach the main sequence so quickly that such detection is highly unlikely.