Satellite Lines: A Probe for the Plasma Conditions in Hot-Star Wind Shocks 

Sean Gunderson; University of Iowa

X-ray satellite lines are a reliable diagnostic of the electron temperature in plasmas in the lab and the Sun’s atmosphere but have not been used in massive stars. The recent deep exposure with the Chandra X-ray Observatory on the prototypical O-type supergiant zeta Puppis provides the first chance do so. I will discuss what satellite lines are, and their capabilities as either a direct measure of the temperature of a plasma or a way to test differential emission measure models for non-isothermal plasmas. The X-ray emitting plasmas of zeta Puppis fall in this latter category, allowing us to test the predictions of the differential emission measure model used by Huenemoerder et al. (2020). In doing so, we find evidence for affirmation of the X-ray emitting plasma being in a state of collisional ionization equilibrium and reject the alternative plasma state called Pollock’s paradigm.