We present an analysis of XMM-Newton observations of the superbubble 30 Dor C and compare the results with the predictions from the standard wind-blown bubble model .
We find that the observed X-ray spectra can not be fitted satisfactorily with the model alone and that there is evidence for nonthermal X-ray emission , which is particularly important at \mathrel { \hbox { \raise 2.15 pt \hbox { $ > $ } \hbox to 0.0 pt { \lower 2.15 pt \hbox { $ \sim$% } } } } 4 keV .
The combination of the bubble model and a power-law gives a reasonable fit to the observed spectra .
The thermal pressure and central temperature of the bubble are 3.3 \times 10 ^ { -11 } dyne cm ^ { -2 } and 7.4 \times 10 ^ { 6 } K , respectively , and we infer that , for a bubble age of t \sim 4 \times 10 ^ { 6 } years , the ambient density is n _ { 0 } \simeq 38 cm ^ { -3 } , the mechanical luminosity is L _ { mech } \sim 10 ^ { 37 } erg s ^ { -1 } , and the coefficient of thermal conductivity is \sim 0.05 of the Spitzer value .
The total unabsorbed 0.1 – 10 keV luminosities of the eastern and western parts of the bubble are \simeq 3 \times 10 ^ { 36 } 
erg s ^ { -1 } and \simeq 5 \times 10 ^ { 36 } erg s ^ { -1 } , respectively .
The unabsorbed 0.1 – 10 keV luminosity of the bubble model is \sim 4 \times 10 ^ { 36 } erg s ^ { -1 } and so the power-law component contributes between 1 / 3 and 1 / 2 to the total unabsorbed luminosity in this energy band .
The nature of the hard nonthermal emission is not clear , although recent supernovae in the bubble may be responsible .
We expect that about one or two core-collapse supernovae could have occured and are required to explain the enrichment of the hot gas , as evidenced by the overabundance of \alpha -elements by a factor of \gtrsim 3 , compared to the mean value of \sim 0.5 solar for the interstellar medium in the Large Magellanic Cloud .
As in previous studies of various superbubbles , the amount of energy currently present in 30 Dor C is significantly less than the expected energy input from the enclosed massive stars over their lifetime .
We speculate that a substantial fraction of the input energy may be radiated in far-infrared by dust grains , which are mixed with the hot gas because of the thermal conduction and/or dynamic mixing .