Exploring how stars expel materials that form planets and life

Susanne Höfner and her research team will develop new models of winds of cool giant and supergiant stars to explore processes that lead to dust formation and wind acceleration. The research will contribute to a better understanding of how newly formed elements travel through space. 

In early 2020, the brightness of the red supergiant Betelgeuse decreased so much that the change was visible to the naked eye. Observations using various instruments showed that the star was expelling a massive cloud of gas into space, obscuring part of the hot glowing surface. This was completely unexpected, and there was much speculation about what could be behind the phenomenon. There are still no consistent physical models to explain the observations – and Höfner and her research team want to change that. 

The formation of elements in stars is a central theme of astrophysics with many links to other fields of research. It is a well-known fact today that almost all atoms in our environment and in our own bodies have been formed by nuclear processes in different types of stars. But how do the newly formed elements leave their stars of origin and travel through space so that they can be involved in the formation of planets and the emergence of life?

Stellar winds disperse material from surface layers

A temptingly short answer is: supernova explosions. But this is not the whole story. Numerous observations show that stellar winds transport material away from a star’s surface layers, or the stellar atmosphere, for most of a star's lifetime. The solar wind is a well-known example of this. 

Powerful telescopes can now provide images of stars at a resolution that was previously not possible. The research team’s goal is to construct three-dimensional computer models describing the atmospheres and winds to compare with observations and thus contribute to the understanding of how stars disperse materials that can give rise to planets and life.

Photo: Mikael Wallerstedt