ON THE FU ORIONIS VARIABLE V1515 CYGNI

We present optical/infrared photometric and spectroscopie observations of the pre-mainsequence FU Ori object V1515 Cyg. Our observations show this variable star has many features in common with other FU Orionis objects, including a variation of spectral type with wavelength of observation, strong 2.3 μm CO absorption bands, and a large infrared excess. These features are consistent with our accretion disk model for FU Ori eruptions. We interpret the 1980 optical photometric minimum as a dust condensation event in the outflowing wind of V1515 Cyg—the slow recovery from the minimum was caused by expansion of the dust cloud in the wind. The depth of the minimum and the recovery time suggest dust formation occurred in material with a temperature of 500 K-700 at a radial distance of 1-2 × 1015 cm from the mass-losing source. A mass-loss rate of 1-3 × 10−5M⊙ yr−1 can produce the conditions required for dust formation in the wind of V1515 Cyg; this result agrees with previous estimates of the mass-loss rate in this system.