2002ApJ...565L..59M

Some hot, massive, Population I Wolf-Rayet (W-R) stars of the carbon subclass are known to be prolific dust producers. How dust can form in such a hostile environment remains a mystery. Here we report the discovery of a relatively cool, extended, multiarc dust envelope around the star WR 112, most likely formed by wind-wind collision in a long-period binary system. We derive the binary orbital parameters, the dust temperature, and the dust mass distributions in the envelope. We find that amorphous carbon is a main constituent of the dust, in agreement with earlier estimates and theoretical predictions. However, the characteristic size of the dust grains is estimated to be ∼1 µm, significantly larger than theoretical limits. The dust production rate is 6.1x10^–7 M_☉ yr^–1, and the total detectable dust mass is found to be about 2.8x10^–5 M_☉ (for d=4.15 kpc). We also show that, despite the hostile environment, at least ∼20% of the initially formed dust may reach the interstellar medium.