Early spectral evolution of Nova Sagittarii 2004 (V5114 Sagittarii)

Aims. We present optical and near-infrared spectral evolution of the Galactic nova V5114 Sgr (2004) during few months after the outburst. Methods. We use multi-band photometry and line intensities derived from spectroscopy to put constrains on the distance and the physical conditions of the ejecta of V5114 Sgr. Results. The nova showed a fast decline to - 11 days) and spectral features of Fen spectroscopic class. It reached Mv = -8.7 ± 0.2 mag at maximum light, from which we derive a distance of 7700 ± 700 kpc and a distance from the galactic plane of about 800 pc. Hydrogen and oxygen mass of the ejecta are measured from emission lines, leading to ∼10-6 and 10-7 M⊙, respectively. We compute the filling factor of the ejecta to be in the range 0.1-10-3. We found the value of the filling factor to decrease with time. The same is also observed in other novae, then giving support to the idea that nova shells are not homogeneously filled in, rather being the material clumped in relatively higher density blobs less affected by the general expanding motion of the ejecta. © ESO 2006