On the Evolution of the Late-time {\it Hubble Space Telescope} Imaging   of the Outburst of the Recurrent Nova RS Ophiuchi (2006)
  We modelled the late-time {\it Hubble Space Telescope} imaging of RS Ophiuchi with models from Ribeiro et al. (2009), which at the time due to the unknown availability of simultaneous ground-based spectroscopy left some open questions as to the evolution of the expanding nebular from the early to the late time observations. Initial emission line identifications suggest that no forbidden lines are present in the spectra and that the emission lines arising in the region of the WFPC2 F502N images are due to N{\sc ii} and He{\sc i} + Fe{\sc ii}. The best model fit to the spectrum is one where the outer faster moving material expands linearly with time while the inner over-density material either suffered some deceleration or did not change in physical size. The origin of this inner over-density requires further exploration. 
Val\'erio A. R. M. Ribeiro, Michael F. Bode, and Robert E. Williams
astro-ph.SR