A Herbig Ae/Be star (HABe) is a pre-main-sequence star – a young (<10Myr) star of spectral types A or B. These stars are still embedded in gas-dust envelopes and are sometimes accompanied by circumstellar disks. Hydrogen and calcium emission lines are observed in their spectra. They are 2-8 Solar mass  objects, still existing in the star formation (gravitational contraction) stage and approaching the main sequence (i.e. they are not burning hydrogen in their center). In the Hertzsprung–Russell diagram these stars are located to the right of the main sequence. They are named after the American astronomer George Herbig, who first distinguished them from other stars in 1960. The original Herbig criteria were:

• Spectral type earlier than F0 (in order to exclude T Tauri stars),
• Balmer emission lines in the stellar spectrum (in order to be similar to T Tauri stars),
• Projected location within the boundaries of a dark interstellar cloud (in order to select really young stars near their birthplaces),
• Illumination of a nearby bright reflection nebula (in order to guarantee physical link with star formation region).