Herbig Ae/Be star

Lore & Background

George Herbig first distinguished Herbig Ae/Be stars from other stars in 1960. The original criteria for identifying them have been revised, as some isolated examples not connected with dark clouds or nebulae are now known. The most reliable current criteria reflect this. These stars often show significant brightness variability, believed to be caused by clumps such as protoplanets and planetesimals in their circumstellar disks. During the lowest brightness stage, the star's radiation becomes bluer and linearly polarized, an effect similar to the blue color of Earth's sky.

Reader's Guide

Herbig Ae/Be stars are significant as intermediate-mass pre-main-sequence objects that bridge the gap between lower-mass T Tauri stars and higher-mass stars that evolve too quickly to be observed in the pre-main-sequence stage. Their study provides insights into star formation, circumstellar disk evolution, and planet formation. The presence of planets around some Herbig Ae/Be stars, such as HD 95086 b, HD 100546 b, and AB Aurigae b, underscores their importance as laboratories for understanding planetary system development. Their variability, linked to disk clumps, offers direct observational evidence of protoplanetary and planetesimal activity. The classification criteria have evolved to account for isolated examples, reflecting ongoing refinement in stellar astronomy.

Did You Know?

• Herbig Ae/Be stars are named after American astronomer George Herbig, who first distinguished them in 1960.
• They show hydrogen and calcium emission lines in their spectra.
• Their brightness variability is believed to be due to clumps (protoplanets and planetesimals) in the circumstellar disk.
• Analogs of Herbig Ae/Be stars in the smaller mass range (<2 solar masses) are called T Tauri stars.