The morphology of the expanding ejecta of V2491 Cygni (2008 N.2)




Determining the evolution of the ejecta morphology of novae provides valuable information on the shaping mechanisms in operation at early stages of the nova outburst. Understanding such mechanisms has implications for studies of shaping for example in proto-Planetary Nebulae. Here we perform morpho-kinematical studies of V2491 Cyg using spectral data to determine the likely structure of the ejecta and its relationship to the central system and shaping mechanisms. We use shape to model different morphologies and retrieve their spectra. These synthetic spectra are compared with observed spectra to determine the most likely morphology giving rise to them, including system inclination and expansion velocity of the nova ejecta. We find the best-fitting remnant morphology to be that of polar blobs and an equatorial ring with an implied inclination of 80+3−12 degrees and an maximum expansion velocity of the polar blobs of 3100+200−100 km s−1 and for the equatorial ring 2700+200−100 km s−1. This inclination would suggest that we should observe eclipses which will enable us to determine more precisely important parameters of the central binary. We also note that the amplitude of the outburst is more akin to the found in recurrent nova systems.