The Joys of Applying UV Spectroscopy to Understanding the Solar-Stellar Connection and Related Topics in Astrophysics

For more than 40 years a central theme of my research has been the application of spectroscopy mostly at ultraviolet wavelengths to a clearer understanding of phenomena and physical processes occuring in the outer atmospheres of the Sun, cool stars, premain sequence stars, and the interstellar medium near the Sun. The sensitivity and spectral resolution available for this work has increased enormously over time. My thesis involved the analysis of solar chromosphere spectra of the Ca II H and K lines using the McMath-Pierce solar telescope on Kitt Peak. Then with spectra from the Copernicus and IUE satellites and the GHRS, STIS, and COS instruments on HST, I extended this research to the study of stellar chromospheres. The availability of X-ray observations and spectra with HEAO-1, Einstein, XMM-Newton, and Chandra observatories opened up the study of stellar coronae. Absorption lines observed against stellar emission lines are not noise but important signals leading to a better understanding of the local interstellar medium, deuterium in the Galaxy, and even mass loss from a transiting planet. In all of these research areas, I have had the pleasure of working with and learning from many stimulating graduate students and postdocs.

In this talk I will select several key discoveries in the above topics, summarize our present understanding of these topics, identify what we need to understand better, and suggest what observational and theoretical advances should be pursued to improve our understanding.