We present the analysis of XMM-Newton archival observations towards the Wolf-Rayet ( WR ) bubble around WR 16 .
Despite the closed bubble morphology of this WR nebula , the XMM-Newton observations show no evidence of diffuse emission in its interior as in the similar WR bubbles NGC 6888 and S 308 .
We use the present observations to estimate a 3- \sigma upper limit to the X-ray luminosity in the 0.3–1.5 keV energy band equal to 7.4 \times 10 ^ { 32 } erg s ^ { -1 } for the diffuse emission from the WR nebula , assuming a distance of 2.37 kpc .
The WR nebula around WR 16 is the fourth observed by the current generation of X-ray satellites and the second not detected .
We also examine FUSE spectra to search for nebular O vi absorption lines in the stellar continuum of WR 16 .
The present far-UV data and the lack of measurements of the dynamics of the optical WR bubble do not allow us to confirm the existence of a conductive layer of gas at T \sim 3 \times 10 ^ { 5 } K between the cold nebular gas and the hot gas in its interior .
The present observations result in an upper limit of n _ { \mathrm { e } } < 0.6 cm ^ { -3 } on the electron density of the X-ray emitting material within the nebula .