Spectrophotometric evolution of Nova Delphini 2013

ATel #5370; T. N. Tarasova, D. N. Shakhovskoi (Crimean Astrophysical Observatory)
on 6 Sep 2013; 11:43 UT
Credential Certification: Taya Tarasova (taya_tarasova@mail.ru)

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We continue spectrophotometric observations with the 2.6 m telescope of CrAO (the first results were reported in our previous telegram ATel5291). We carried out observations on August 19 and on September 1 with low resolution spectrograph (R=1000) in the wavelength interval 3300-7575A and on August 20 with high resolution echelle spectrograph (R=33000) in the wavelength interval 4300-7200A. Analyzing low resolution spectra we found drastic changes in the spectral energy distribution (SED) of the nova. The first spectrum (ATel5291) was obtained in the pre-maximal stage and the SED was similar to late A or early F spectrum. On Aug 19 the SED was rather flat, with the Balmer jump virtually absent and on September 1 the SED was still flat, but with pronounced emission bluewards of the Balmer jump. We confirm that the depth of the absorption component of the P Cygni profiles of HI lines reached roughly to the continuum level in the Aug 19 spectrum, as reported in ATel 5297, 5300. In the Aug 19 spectrum lines CaII (3934, 3968) and NaI (5890, 5896) were strong, as mentioned by Munari et al.(ATel 5297). In the Sep 1 spectrum [OI] 6300, 6363 lines appeared. At the same spectrum there is a noticeable broad emission feature about 7111 A that we tentatively identify as CII (20) 7112.36, 7115.12 lines and a weaker feature about 6725A, which we identify as CII (21) 6726.84, 6733.56, 6738.36 lines. In Sep 1 spectrum the profiles of emission Balmer lines were saddle-shaped with the different intensities of the components, the blue emission component was stronger. The radial velocities of the blue and the red components were -40, 560 km/s for Halpha, -110, 460 km/s for Hbeta and -100, 410 km/s for Hgamma. In the high resolution spectrum obtained on Aug 20 the equivalent width of the NaI 5890 absorption line was 0.386 ±0.003 A, coinciding within measurement errors with the value reported by Munari et al. .(ATel 5297).