Gaia 18dvy : a new FUor in the Cygnus OB3 association
E. Szegedi-Elek, P. Ábrahám, Ł. Wyrzykowski, M. Kun, Á. Kóspál, L. Chen, G. Marton, A. Moór, Csaba Kiss, András Pál, L. Szabados, J. Varga, E. Varga-Verebélyi, Claire Larsen Andreas, E. Bachelet, Richard J. Bischoff, Attila Bódi, E. Breedt, U. Burgaz, T. Butterley, Carrasco, JM, V. Čepas, G. Damljanović, İ. Gezer, V. Godunova, M. Gromadzki, A. Gurgul, L. K. Hardy, F. Hildebrandt, Susanne M. Hoffmann, M. Hundertmark, N. Ihanec, R. Janulis, Kalup, C, Zofia Kaczmarek, Réka Könyves-Tóth, Máté Krezinger, K. Kruszyńska, S. P. Littlefair, M. Maskoliūnas, László Mészáros, P. Mikołajczyk, M. Mugrauer, H. Netzel, A. Ordasi, E. Pakštienė, Rybicki, KA, K. Sárneczky, B. Seli, A. Simon, K. Šiškauskaitė, Á. Sódor, Sokolovsky, KV, W. Stenglein, R. A. Street, Róbert Szakáts, L. Tomasella, Y. Tsapras, K. Vida, J. Zdanavičius, M. Zieliński, Paweł Zieliński, O. Ziółkowska
Abstract
We present optical-infrared photometric and spectroscopic observations of Gaia18dvy, located in the Cygnus OB3 association at a distance of 1.88 kpc. The object was noted by the Gaia alerts system when its lightcurve exhibited a $\gtrsim$4 mag rise in 2018-2019. The brightening was also observable at mid-infared wavelengths. The infrared colors of Gaia18dvy became bluer as the outburst progressed. Its optical and near-infrared spectroscopic characteristics in the outburst phase are consistent with those of bona fide FU Orionis-type young eruptive stars. The progenitor of the outburst is probably a low-mass K-type star with an optical extinction of $\sim$3 mag. A radiative transfer modeling of the circumstellar structure, based on the quiescent spectral energy distribution, indicates a disk with a mass of $4{\times}10^{-3}\,M_{\odot}$. Our simple accretion disk modeling implies that the accretion rate had been exponentially increasing for more than 3 years until mid-2019, when it reached a peak value of $6.9 \times 10^{-6}\,M_{\odot}$yr$^{-1}$. In many respects, Gaia18dvy is similar to the FU Ori-type object HBC 722