2014MNRAS.440.3402M

BVRCIC photometry and low-, medium- and high-resolution echelle fluxed spectroscopy is presented and discussed for three faint, heavily reddened novae of the Feii-type which erupted in 2013. V1830 Nova Aql 2013 reached a peak V = 15.2 mag on 2013 Oct 30.3ut and suffered from a huge E(B - V) ∼ 2.6 mag reddening. After a rapid decline, when the nova was ΔV = 1.7 mag below maximum, it entered a flat plateau where it remained for a month until solar conjunction prevented further observations. Similar values were observed for V556 Nova Ser 2013, that peaked near RC ∼ 12.3 around 2013 Nov 25 and soon went lost in the glare of sunset sky. A lot more observations were obtained for V809 Nova Cep 2013, that peaked at V = 11.18 on 2013 Feb 3.6. The reddening is E(B - V) ∼ 1.7 and the nova is located within or immediately behind the spiral Outer Arm, at a distance of ∼ 6.5 kpc as constrained by the velocity of interstellar atomic lines and the rate of decline from maximum. While passing at t3, the nova begun to form a thick dust layer that caused a peak extinction of ΔV > 5 mag, and took 125 d to completely dissolve. The dust extinction turned from neutral to selective around 6000Å. Monitoring the time evolution of the integrated flux of emission lines allowed us to constrain the region of dust formation in the ejecta to be above the region of formation of Oi 7774Å and below that of Caii triplet. Along the decline from maximum and before the dust obscuration, the emission line profiles of Nova Cep 2013 developed a narrow component (FWHM = 210 km/s) superimposed on to the much larger normal profile, making it a member of the so-far exclusive but growing club of novae displaying this peculiar feature. Constrains based on the optical thickness of the innermost part of the ejecta and on the radiated flux, place the origin of the narrow feature within highly structured internal ejecta and well away from the central binary.