X-ray emission from O-type stars : DH Cep and HD 97434

TL;DR

This paper analyzes X-ray emissions from two O-type stars, DH Cep and HD 97434, revealing their spectral characteristics and supporting the wind shock model without evidence of short-term variability.

Contribution

It provides detailed X-ray spectral analysis of DH Cep and HD 97434, confirming the wind shock model and showing consistency with reddening measurements.

Findings

X-ray spectra fit two-temperature plasma models

No short-term X-ray variability detected

Hydrogen column densities match reddening data

Abstract

We present X-ray emission characteristics of the massive O-type stars DH Cep and HD 97434 using archival XMM-Newton observations. There is no convincing evidence for short term variability in the X-ray intensity during the observations. However, the analysis of their spectra reveals X-ray structure being consistent with two-temperature plasma model. The hydrogen column densities derived from X-ray spectra of DH Cep and HD 97434 are in agreement with the reddening measurements for their corresponding host clusters NGC 7380 and Trumpler 18, indicating that the absorption by stellar wind is negligible. The X-ray emission from these hot stars is interpreted in terms of the standard instability-driven wind shock model.