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arXiv · 2003.06889

A Deep Exposure in High Resolution X-Rays Reveals the Hottest Plasma in the $\zeta\,$Puppis Wind

David P. Huenemoerder·Richard Ignace·Nathan A. Miller·Kenneth G. Gayley·Wolf-Rainer Hamann·Jennifer Lauer·Anthony F. J. Moffat·Yaël Nazé·Joy S. Nichols·Lidia Oskinova·Noel D. Richardson·Wayne Waldron
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Abstract

We have obtained a very deep exposure (813 ks) of $\zeta\,$Puppis (O4 supergiant) with the Chandra/HETG Spectrometer. Here we report on analysis of the 1-9 \r{A} region, especially well suited for Chandra, which has a significant contribution from continuum emission between well separated emission lines from high-ionization species. These data allow us to study the hottest plasma present through the continuum shape and emission line strengths. Assuming a powerlaw emission measure distribution which has a high-temperature cut-off, we find that the emission is consistent with a thermal spectrum having a maximum temperature of 12 MK. This implies an effective wind shock velocity of $900\,\mathrm{km\,s^{-1}}$, well below the wind terminal speed of $2250\,\mathrm{km\,s^{-1}}$. For X-ray emission which forms close to the star, the speed and X-ray flux are larger than can be easily reconciled with strictly self-excited line-deshadowing-instability models, suggesting a need for a fraction of the wind to be accelerated extremely rapidly right from the base. This is not so much a dynamical instability as a nonlinear response to changing boundary conditions.

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David P. Huenemoerder, Richard Ignace, Nathan A. Miller, Kenneth G. Gayley, Wolf-Rainer Hamann, Jennifer Lauer, Anthony F. J. Moffat, Yaël Nazé, Joy S. Nichols, Lidia Oskinova, Noel D. Richardson, Wayne Waldron. 2020-03-15. A Deep Exposure in High Resolution X-Rays Reveals the Hottest Plasma in the $\zeta\,$Puppis Wind. https://doi.org/10.3847/1538-4357/ab8005

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