Condensation of dust around the Wolf-Rayet star WR 125

Williams, P. M.; van der Hucht, K. A.; Bouchet, P.; Spoelstra, T. A. Th.; Eenens, P. R. J.; Geballe, T. R.; Kidger, M. R.; Churchwell, E.
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Monthly Notices of the Royal Astronomical Society (ISSN 0035-8711), vol. 258, no. 3, p. 461-472.

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Infrared photometry of the WC7-type Wolf-Rayet star WR 125 (MR 93) in 1981-91 shows a 10-fold rise in the 3-4 micron flux during 1990-91. This, together with observations at longer wavelengths, is interpreted in terms of the condensation of dust in its wind, similar to the events observed from episodic dust-making WR stars like WR 48a in 1979-80 and WR 140 in 1977 and 1985. Dust condensation started in 1990.6 and has continued for at least a year at a rate of 2.3 x 10 exp -7 solar mass/yr, about 0.4 percent of the mass-loss rate. The precondensation photometry of its stellar wind indicates that WR 125 is 3.5 times as distant as WR 140, namely 4.7 kpc away. The optical emission-line spectrum of WR 125 is diluted almost as much as that of WR 140, presumably by the continuum of a hot companion, although we have been unable to find any absorption lines from it in the 4370-4770 wavelength region. From the profile of the He I 1.083-micron line in our infrared spectrum, a wind velocity of 2900 km/s is determined, similar to that of WR 140, suggesting that the new dust shell will be dissipated on a time scale (about 4 yr) comparable to that of WR 140.