Herbig AE/BE stars

Definition

Herbig AE/BE stars are a class of young, pre-main sequence stars that possess spectral types A and B, indicating they are more massive than typical T Tauri stars. These stars are still in the process of forming and exhibit significant infrared excess due to the surrounding circumstellar material, which plays a crucial role in the study of protostellar evolution and the characteristics of young stellar objects.

5 Must Know Facts For Your Next Test

1. Herbig AE/BE stars typically have masses ranging from 2 to 8 solar masses and are found in star-forming regions.
2. These stars often exhibit strong emission lines in their spectra, indicating active accretion of material from their surrounding environment.
3. The infrared excess observed in Herbig AE/BE stars is a result of heated dust in their circumstellar disks, which provides insights into the star formation process.
4. Herbig AE/BE stars can display phenomena such as jets and outflows, similar to those seen in T Tauri stars, further showcasing their youth and ongoing development.
5. Due to their relative brightness and proximity, Herbig AE/BE stars are ideal candidates for studying the early stages of stellar evolution and the dynamics of circumstellar material.

Review Questions

• How do Herbig AE/BE stars differ from T Tauri stars in terms of mass and evolutionary stage?
  • Herbig AE/BE stars differ from T Tauri stars primarily in their mass and spectral classification. While T Tauri stars have lower masses (typically less than 2 solar masses), Herbig AE/BE stars range from about 2 to 8 solar masses. This difference indicates that Herbig AE/BE stars are at a more advanced evolutionary stage, as they are larger and more luminous, being classified as pre-main sequence stars still forming within their circumstellar environments.
• Discuss the significance of infrared excess in understanding the characteristics of Herbig AE/BE stars.
  • The infrared excess in Herbig AE/BE stars is significant because it reveals the presence of heated dust in their surrounding circumstellar disks. This excess allows astronomers to understand the physical conditions around these young stars, including the density and temperature of the material being accreted. By studying this infrared radiation, researchers can gain insights into how these stars are forming, the processes involved in accretion, and the potential for planet formation in their disks.
• Evaluate the role of Herbig AE/BE stars in advancing our knowledge of stellar evolution and formation processes.
  • Herbig AE/BE stars play a crucial role in advancing our understanding of stellar evolution and formation processes due to their unique characteristics as young, massive pre-main sequence stars. Their significant infrared excess allows scientists to study the dynamics of circumstellar disks and accretion phenomena, providing a clearer picture of how more massive stars evolve compared to lower-mass counterparts like T Tauri stars. Additionally, examining jets and outflows associated with these stars enhances our knowledge of angular momentum transfer during star formation, helping us understand the complex interplay between star growth and the surrounding material.

Related terms

T Tauri stars: A group of young stars that are less massive than Herbig AE/BE stars and are characterized by variability and strong solar-like activity.

Circumstellar disk: A rotating disk of dense gas and dust surrounding a young star, which is critical for star formation and planet formation processes.

Stellar formation: The process by which dense regions within molecular clouds collapse under their own gravity to form stars, involving various phases including protostars, pre-main sequence stars, and main sequence stars.