Thesis Supervisor: Liz Humphreys

Abstract

The route by which low and intermediate mass stars, such as our Sun, evolve to become Red Giants, visually-stunning Planetary Nebulae such as those imaged by the Hubble Space Telescope, and White Dwarfs is complex and not well-understood. Vital to the understanding of this process is a stage in the stellar evolution known as the Asymptotic Giant Branch. Stars evolve onto the Asymptotic Giant Branch several billion years after the current age of the Sun. During this time, they become unstable to pulsations and start to lose mass at a rapid rate (up to twice the mass of the Earth per year). Eventually this mass loss will lead to effective stellar "death" and nuclear fusion reactions in the core will shut off.

This PhD project involves study of stars evolving onto and off the Asymptotic Giant Branch at millimetre and submillimetre wavelengths using state-of-the-art ESO telescopes APEX and ALMA. The key questions that will be investigated include:

(i) how asymmetric and time-dependent is the mass loss process?
(ii) what role do stellar hotspots play in asymmetric mass loss?
(ii) what role do magnetic fields play in shaping planetary nebulae?

It may be possible to complement these data at other wavelengthsusing e.g. infra-red inferferometry (VLTI).

Return to list of thesis topics