Early spectroscopic observations of Nova (V1494) Aquilae 1999 No.2

Abstract

Low- and medium resolution spectra of the fast nova, Nova (V1494) Aql 1999 No.2 obtained approximately 6, 7, 19 and 28 days after the maximum brightness are presented and discussed. The spectrum covering the whole optical range at day 6 shows the principal plus diffuse-enhanced spectrum. The presence of strong Fe II multiplets with P-Cyg profiles suggest that V1494 Aql belongs to the ``Fe II'' class defined by Williams (1992). The medium-resolution profiles (lambda/Delta lambda \approx 7000) of the Hgamma and Hdelta lines show well-defined sharp absorption features with the same radial velocities, while the Halpha split into two distinct emission peaks in the last two spectra (Delta t=19 and 28 days). The observed behaviour suggests an expanding equatorial ring with possible small-scale clumpiness in the nova shell. The visual lightcurve is used to deduce M_V by the maximum magnitude versus rate of decline relationship. The resulting parameters are: t_2=6.6+/-0.5 days, t_3=16+/-0.5 days, M_V=-8.8+/-0.2 mag. Adopting this value, a distance d=3.6+/-0.3 kpc is determined.