X-ray emission from the Wolf-Rayet bubble NGC 6888-II. XMM-Newton EPIC observations

DOI: 
10.1093/mnras/stv2819
Publication date: 
01/03/2016
Main author: 
Toala, J. A.
IAA authors: 
Chu, Y. -H.
Authors: 
Toala, J. A.; Guerrero, M. A.; Chu, Y. -H.; Arthur, S. J.; Tafoya, D.; Gruendl, R. A.
Journal: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Publication type: 
Article
Volume: 
456
Pages: 
4305-4314
Number: 
Abstract: 
We present deep XMM-Newton European Photon Imaging Camera observations of the Wolf-Rayet (WR) bubble NGC 6888 around the star WR 136. The complete X-ray mapping of the nebula confirms the distribution of the hot gas in three maxima spatially associated with the caps and north-west blowout hinted at by previous Chandra observations. The global X-ray emission is well described by a two-temperature optically thin plasma model (T-1 = 1.4 x 10(6) K, T-2 = 8.2 x 10(6) K) with a luminosity of L-X = 7.8 x 10(33) erg s(-1) in the 0.3-1.5 keV energy range. The rms electron density of the X-ray-emitting gas is estimated to be n(e) = 0.4 cm(-3). The high-quality observations presented here reveal spectral variations within different regions in NGC 6888, which allowed us for the first time to detect temperature and/or nitrogen abundance inhomogeneities in the hot gas inside a WR nebula. One possible explanation for such spectral variations is that the mixing of material from the outer nebula into the hot bubble is less efficient around the caps than in other nebular regions.
Database: 
ADS
WOK
SCOPUS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2016MNRAS.456.4305T/abstract
ADS Bibcode: 
2016MNRAS.456.4305T
Keywords: 
stars: Wolf-Rayet; ISM: bubbles; ISM: individual objects: (NGC 6888); X-rays: individual: (NGC 6888); X-rays: individual (WR 136)