X-rays from wind-blown bubbles: an XMM-Newton detection of NGC 2359

TL;DR

This paper reports the first X-ray detection of the wind-blown bubble NGC 2359 using XMM-Newton, revealing thermal plasma emission and insights into the central star's properties and wind dynamics.

Contribution

It provides the first X-ray observation of NGC 2359 and compares it with hydrodynamic models, suggesting a reduced mass-loss rate for the central star WR 7.

Findings

X-ray emission is soft and from thermal plasma at ~0.2 keV.

WR 7 exhibits a two-temperature plasma spectrum.

The observed flux implies a lower mass-loss rate than previous estimates.

Abstract

We present an analysis of the XMM-Newton observation of the wind-blown bubble NGC 2359. This is the first detection of this object in X-rays. The X-ray emission of NGC 2359 is soft and originates from a thermal plasma with a typical temperature of kT ~ 0.2 keV. A direct comparison between the one-dimensional hydrodynamic model of wind-blown bubbles and the X-ray spectrum of NGC 2359 suggests a reduced mass-loss rate of the central star in order to provide the correct value of the observed flux. The central star of the nebula, WR 7, is an X-ray source. Its emission is similar to that of other presumably single Wolf-Rayet stars detected in X-rays. The WR 7 spectrum is well represented by the emission from a two-temperature plasma with a cool component of kT ~ 0.6 keV and a hot component of kT ~ 2.7 keV.