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Published online by Cambridge University Press: 26 May 2016
The massive, long-period and highly-eccentric (P = 2899 d, e = 0.88), colliding-wind binary WR 140 (WC7pd+O4-5) may be regarded as a clock-work for its predictable, repeatable IR outbursts related to dust formation right after each periastron passage. However, the 2001 periastron passage broke this monotonic trend. Our UBV photometry, completely covering the past nine years, shows a series of quasi-regular fadings starting ~ 2 months after periastron passage (Φ ≃ 0.02-0.05). Preliminary analysis points to dust as a probable cause of the eclipse-like behavior of the system, while the oscillating pattern hints towards instabilities in the wind-wind collision zone. At the same time, contemporaneous spectroscopy shows nothing unusual aside of the strong, but short-lived signs of wind-wind interaction (Φ ≃ 0.99-1.02).