The infrared emission features in the spectrum of the Wolf-Rayet star WR 48a

We present the first detection of unidentified infrared (UIR) emission features at similar to6.4 and 7.9 mum in the spectrum of the dusty WC8 Wolf-Rayet star WR 48a. Based on the H-deficient nature of WC stars, we attribute the emission features to large carbonaceous molecules or amorphous carbon dust grains in the circumstellar environment of WR 48a. The 6.4 mum feature resembles the emission feature seen toward H-deficient planetary nebulae (PNe), while the 7.9 mum profile resembles that of some PNe with H-deficient WC10 central stars. These similarities point toward a similar origin of the dust in these H-deficient environments and highlights the apparent sensitivity of the UIR bands to physical conditions. In the case of WR 48a and the [WC10] PNe, shock processing may play a major role in dust formation