Herbig Ae/Be Stars – Definition & Detailed Explanation – Astrophysics Glossary

I. What are Herbig Ae/Be Stars?

Herbig Ae/Be stars are young, intermediate-mass stars that are still in the process of forming. They belong to the larger category of pre-main-sequence stars, which are stars that have not yet reached the main sequence phase of their evolution. Herbig Ae/Be stars are named after the astronomers George Herbig and Guillermo Haro, who first identified them in the 1940s and 1950s.

These stars are typically found in regions of active star formation, such as stellar nurseries or star-forming regions within galaxies. They are characterized by their strong infrared emissions, which are produced by the surrounding dusty disks of gas and dust that are still in the process of accreting onto the star.

II. How are Herbig Ae/Be Stars formed?

Herbig Ae/Be stars are formed through the process of gravitational collapse within molecular clouds. These clouds are composed of gas and dust, and when a region of the cloud becomes dense enough, gravity begins to pull the material together. As the material collapses, it forms a protostar at the center, which eventually becomes a Herbig Ae/Be star.

During the formation process, the protostar is surrounded by a rotating disk of gas and dust, known as a protoplanetary disk. This disk is where planets and other celestial bodies are believed to form. As the protostar continues to accrete material from the disk, it grows in mass and eventually reaches the point where nuclear fusion reactions begin in its core, marking the transition to a fully-fledged star.

III. What are the characteristics of Herbig Ae/Be Stars?

Herbig Ae/Be stars are characterized by their youth and relatively high mass compared to other pre-main-sequence stars. They typically have masses between 2 and 8 times that of the Sun, and are several thousand times more luminous. These stars also have strong stellar winds and are surrounded by circumstellar disks of gas and dust.

One of the key features of Herbig Ae/Be stars is their strong infrared emissions, which are produced by the heating of the surrounding dusty disks by the star’s radiation. This makes them ideal targets for study using infrared telescopes and other instruments that can penetrate the dusty environments in which they are found.

IV. What is the significance of studying Herbig Ae/Be Stars?

Studying Herbig Ae/Be stars is important for understanding the process of star formation and the early stages of stellar evolution. These stars provide valuable insights into the conditions and mechanisms that lead to the formation of stars and planetary systems, including our own.

By studying Herbig Ae/Be stars, astronomers can learn more about the physical processes that govern the formation of stars and planets, as well as the role of circumstellar disks in shaping the evolution of young stars. This knowledge can help us better understand the origins of our own solar system and the diversity of planetary systems that exist in the universe.

V. How do Herbig Ae/Be Stars evolve?

As Herbig Ae/Be stars continue to accrete material from their surrounding disks, they eventually reach a point where the disk dissipates and the star enters the main sequence phase of its evolution. At this stage, the star begins to burn hydrogen in its core through nuclear fusion reactions, producing energy and heat that radiate out into space.

Over time, Herbig Ae/Be stars will continue to evolve on the main sequence, burning through their hydrogen fuel and eventually expanding into red giants or supernovae, depending on their mass. The fate of a Herbig Ae/Be star is determined by its initial mass and the amount of material it is able to accrete during its formation.

VI. What are some examples of Herbig Ae/Be Stars in the universe?

There are several well-known examples of Herbig Ae/Be stars in the universe, including HD 100546, HD 163296, and MWC 297. These stars are located in various star-forming regions within our galaxy and exhibit the characteristic features of Herbig Ae/Be stars, such as strong infrared emissions and circumstellar disks.

HD 100546, also known as the “Flying Saucer Star,” is a particularly interesting example of a Herbig Ae star due to its unusual disk structure and the presence of a possible giant planet orbiting the star. This star has been the subject of extensive study by astronomers seeking to understand the processes that govern the formation of planetary systems around young stars.

Overall, Herbig Ae/Be stars play a crucial role in our understanding of star formation and the early stages of stellar evolution. By studying these young, intermediate-mass stars, astronomers can gain valuable insights into the origins of stars and planets, as well as the diverse range of phenomena that shape the universe around us.