Griffin, (R) Elizabeth

Contact Email: remg@astro.ox.ac.uk
Institute:
Subject Area: Binary Stars: Non-interacting
Waveband: Optical
Technique: Spectroscopy
Presentation: Poster Display
Title: The inconstancy of stellar chromospheres
Abstract: Measurements of features in the chromospheres of the cool supergiants in zeta Aurigae systems such as 31 Cyg and zeta Aur reveal both long-term and short-term changes. New data of both types will be presented. Long-term changes are seen in archival spectra (dating back to 1939) which have recently been digitized for the first time; short-term changes in zeta Aur are obvious from observations of the Ca II K line for 3 weeks during eclipse ingress/egress. Studies of the properties that are changing should aid our understanding of the mechanism(s) responsible for the structure and support of a stellar chromosphere and the stellar wind.