Near-infrared observations of the novae V2491 Cygni and V597 Puppis

Abstract

We present results obtained from near‐infrared JHK spectroscopic observations of novae V2491 Cygni and V597 Puppis in the early declining phases of their 2007 and 2008 outbursts, respectively. In both objects, the spectra displayed emission lines of H i, O i, He i and N i. In V597 Pup, the He i lines were found to strengthen rapidly with time. Based on the observed spectral characteristics, both objects are classified as He/N novae. We have investigated the possibility of V2491 Cyg being a recurrent nova as has been suggested. By studying the temporal evolution of the linewidths in V2491 Cyg, it appears unlikely that the binary companion is a giant star with heavy wind as in recurrent novae of the RS Oph type. Significant deviations from that of recombination case B conditions are observed in the strengths of the H i lines. This indicates that the H i lines, in both novae, are optically thick during the span of our observations. The slope of the continuum spectra in both cases was found to have a λ−(3−3.5) dependence which deviates from a Rayleigh–Jeans spectral distribution. Both novae were detected in the post‐outburst supersoft X‐ray phase; V2491 Cyg being very bright in X‐rays has been the target of several observations. We discuss and correlate our infrared observations with the observed X‐ray properties of these novae.

Near-infrared studies of the 2010 outburst of the recurrent nova U Scorpii

“…2. The spectra are similar to those seen in novae outbursts occurring on massive WDs, examples of which are V597 Pup, V2491 Cyg and RS Oph (Banerjee, Das & Ashok 2009; Naik et al 2009). The prominent features detected in U Sco are the He i 1.0830 μm and Paγ1.0938 μm lines (blended), O i 1.1287 μm, Paβ1.2818 μm, He i 2.0581 μm and the H i Brackett series lines in the H band.…”

“…Subsequent reduction of the spectra and processing of the photometric data follow a standard procedure that is described for, e.g. in Naik, Banerjee & Ashok (2009). All data reduction was done using iraf tasks.…”

The 2010 nova outburst of the symbiotic Mira V407 Cyg

“…The detailed reduction of the spectral and photometric data, using iraf tasks, follows a standard procedure that is described e.g. in Naik, Banerjee & Ashok (2009) . The journal of IR spectroscopic observations is given in Table S3, and the results of IR photometry in Table S4 and Fig.…”

Unresolved X-ray emission in M31 and constraints on progenitors of classical novae

“… References are from: b Shafter (1997)– c Kamath et al (1997)– d Kiss et al (2002)– e Poggiani (2009)– f Vaytet, O'Brien & Rushton (2007)– g Naik, Banerjee & Ashok (2009)– h Lipkin et al (2001)– i Csák et al (2005) …”