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School of Physics Research project in Astrophysics Multiwavelength Observations of Evolved Stars Research supervisor: Prof. Brian Espey, Astrophysics Group Scientific Background / Current Research The project involves observation and theoretical modelling of stellar systems containing evolved giant stars with masses similar to that of our own Sun. Although supernovae are showy objects, stars with mass similar to our Sun are much more plentiful and when they evolve to the red giant stage they begin to lose processed material in the form of a cool wind. These stars contribute a significant quantity of the carbon, nitrogen and oxygen in the interstellar medium, as well as modifying the star’s future evolution. The exact mechanism of mass-loss occurs in non-dusty giants is still unknown. To determine the physical conditions in the outer layers of the star where the wind begins we use binary star systems where a hot companion star is periodically eclipsed by its giant companion. Comparison of eclipsed with uneclipsed spectra enables us to isolate the spectrum of different layers in the giant’s atmosphere and diagnose conditions layer-by-layer with the same relative spatial resolution as the thickness of an onion skin relative to the onion(!) – resolution unobtainable by any other means. Project By using a combination of high resolution ground-based and Top of figure: Uneclipsed data (black, top) and eclipsed data space-borne (including Hubble Space Telescope) spectra, the with model overlaid (in red). physical parameters of the outer atmosphere of a sample of giant Spectra below show FeII template, and other lines. stars will be determined. With these data a complete model will be developed using a state-of-the-art stellar atmosphere code on TCD high performance computing facilities. Funding Applicants should discuss funding with the Research Supervisor. They should apply for funding from the following sources: Irish Research Council (deadline 11 February, 2015), TCD PG Scholarship and School of Physics Studentship schemes. More information / References Previous PhD work: see: http://www.tcd.ie/Physics/Astrophysics/theses.php Contact details [email protected] Room no: SNIAM 3.17 tel. +353 1 896 2680 © 22 January 2015, School of Physics, TCD