Evolution & dynamic environments of Sun-like stars

Supervisor: Professor Sean Matt

This PhD project is ready for an enthusiastic student, who is interested in studies of Sun-like stars and the interface between theory and observations.

Planets are bathed in the violent winds, magnetic fields, and high-energy radiation of their host stars.  This “magnetic activity” in sun-like and low-mass stars is intimately linked to the star’s rotation rate and formation.  This activity also leads to angular momentum loss, which means that both the stellar spin rate and the activity level decrease with time.  Therefore, in order to characterise the environments of stars and planets, we must develop a theoretical understanding of this evolving relationship between the stellar environment, rotation, and activity.  During the late stages of star formation, we are working to understand the magnetic interaction of stars with their accretion disks.  During the main sequence phase, we are studying how stellar winds influence the environments and rotation rates of stars.

Figures: (left) Model of young, magnetised, star interacting with an accretion disk: arrows show accretion onto the star and a disk wind; (middle) twisted magnetic field in the wind from a rapidly rotating star; (right) rotation period predicted by evolution models, compared to observational data. The PhD project will involve crucial development and use of these "spin-evolution" models, which include physical stellar wind torques, derived from the models to the left

For your PhD, you will learn how to compute the rotational evolution of individual stars and entire star clusters, developing the most realistic physical models in the world, and compare with observations of stellar rotation rates and magnetic activity.  You will be involved in interpreting existing and new stellar rotation data (which are pouring in from missions like Kepler/K2, Gaia, TESS, and future missions), discovering new clues about the interiors and environments of stars, and developing a public tool for stellar evolution to be used by the community (built upon the state-of-the-art stellar evolution code MESA).  You will work in a nurturing environment of the vibrant astrophysics group.  The work will provide a critical link between multi-dimensional models of magnetised stellar winds and the observed long-term evolution of stars.  This will change our understanding of how the mass loss and rotation rates of stars evolve with time, help to characterise the radiation and plasma environments of extra-solar planets, and provide a missing link between stellar activity and long-term evolution.

This project is connected to the fields of star/planet formation and evolution.  We seek to understand observations from a range of ground- and space-based observations (e.g., with TESS, Gaia, HST, KEPLER/K2, CoRoT, Chandra & XMM, SPITZER, ALMA, JWST, Rubin/LSST).

For more information contact Professor Sean Matt