Kavli Affiliate: David P. Huenemoerder
| First 5 Authors: Pragati Pradhan, David P. Huenemoerder, Richard Ignace, Joy S. Nichols, A. M. T. Pollock
| Summary:
Identifying trends between observational data and the range of physical
parameters of massive stars is a critical step to the still-elusive full
understanding of the source, structure, and evolution of X-ray emission from
the stellar winds, requiring a substantial sample size and systematic analysis
methods. The emph{Chandra} data archive as of 2022 contains 37 high resolution
spectra of O, B, and WR stars, observed with the emph{Chandra}/HETGS and of
sufficient quality to fit the continua and emission line profiles. Using a
systematic approach to the data analysis, we explore morphological trends in
the line profiles (i.e., O, Ne, Mg, Si) and find that the centroid offsets of
resolved lines versus wavelength can be separated in three empirically-defined
groups based on the amount of line broadening and centroid offset. Using
ion{Fe}{17} (15.01 AA, 17.05 AA) and ion{Ne}{10} $alpha$ (12.13 AA) lines
which are prevalent among the sample stars, we find a well-correlated linear
trend of increasing Full Width Half Maximum (FWHM) with faster wind terminal
velocity. The H-like/He-like total line flux ratio for strong lines displays
different trends with spectral class depending on ion species. Some of the
sources in our sample have peculiar properties (e.g., magnetic and $gamma$
Cas-analogue stars) and we find that these sources stand out as outliers from
more regular trends. Finally, our spectral analysis is presented summarily in
terms of X-ray spectral energy distributions in specific luminosity for each
source, plus tables of line identifications and fluxes.
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