The spectroscopic evolution of V2362 Cyg (Nova Cygni 2006) in the first 15 months after the outburst

We present the optical spectral evolution of the nova V2362 Cyg during the first 15 months after the outburst, from 2006 April to 2007 July. The spectroscopy, performed at the Loiano telescope, Italy, covers the evolution from the early decline to the nebular stage. V2362 Cyg exhibited an unusual secondary outburst during the decline. We have used the optical spectroscopy and photometry to investigate the physical properties of the ejecta and to constrain the nova distance. V2362 Cyg is a fast nova, with decline rates by two or three magnitudes of 4.3 and 15.8 days, respectively. The derived magnitude at maximum is MV=-9.0. The distance is in the range 7.2-15.8 kpc. Our observations during the first decline showed strong emission lines, typical of a Fe II nova; during the secondary outburst the spectrum reverted to features typical of early decline. After the secondary outburst V2362 Cyg entered the nebular phase. The spectroscopic evolution resembles the history of nova V1493 Aql.