Differential Emission Measure Determination of Collisionally Ionized Plasma: II. Application to Hot Stars

摘要

In a previous paper we have described a technique to derive constraints onthe differential emission measure (DEM) distribution, a measure of thetemperature distribution, of collisionally ionized hot plasmas from their X-rayemission line spectra. We apply this technique to the Chandra/HETG spectra ofall of the nine hot stars available to us at the time this project wasinitiated. We find that DEM distributions of six of the seven O stars in oursample are very similar but that theta Ori has an X-ray spectrum characterizedby higher temperatures. The DEM distributions of both of B stars in our samplehave lower magnitudes than those of the O stars and one, tau Sco, ischaracterized by higher temperatures than the other, beta Cru. These resultsconfirm previous work in which high temperatures have been found for theta Oriand tau Sco and taken as evidence for channeling of the wind in magneticfields, the existence of which are related to the stars' youth. Our resultsdemonstrate the utility of our method for deriving temperature information forlarge samples of X-ray emission line spectra.