Infrared observations of PNV J18040967-1803581: a nova likely to form dust.
ATel #11570; Vishal Joshi, Mudit Srivastava and Dipankar P. K. Banerjee (Physical Research Laboratory, Ahmedabad, India)
on 24 Apr 2018; 20:34 UT
Credential Certification: Vishal Joshi (vjoshi@prl.res.in)
Subjects: Infra-Red, Nova, Transient
Referred to by ATel #: 11573
We report near-infrared IJHKs photometric and spectroscopic (0.85 to 2.35 micron region, R ~ 1000) observations of nova PNV J18040967-1803581. Observations were made on UT 2018 April 14.96 using the Near IR camera/spectrograph (NICS) deployed on the 1.2m Mount Abu observatory telescope. Our spectrum distinctly shows various Hydrogen lines of Balmer and Paschen series, O I lines e.g. 1.1287, 1.3164 micron and N I e.g. 1.2461/1.2469 micron. He I 1.0830 micron is present but weak in strength. Emission lines are showing extremely weak P Cyg profile unlike previous optical spectrum(ATel #11528). Presence of strong neutral Carbon lines e.g. 1.0693, 1.1330, 1.6005, 1.6890, 1.9722, 2.1023, 2.2906 micron clearly confirms that the nova is of FeII class (Banerjee and Ashok, 2012, BASI, 40, 243). FWHM of Paschen Beta emission line corresponds to ~1500 km/s.
We have also clearly detected several low excitation lines of Na I e.g. 2.2056, 2.2084 micron and Mg I 1.504, 1.7109 micron in emission. These lines form from elements of low ionization potential (~5 to 7 eV) relative to that of H, O or N (~13 to 14 eV) and are good indicators of potential dust formation as they imply the presence of a cool zone (Das et al., 2008, MNRAS, 391, 1874). Dust has always formed in a nova when these lines were seen in its NIR spectrum. We, thus, expect Nova PNV J18040967-1803581 to form dust. NIR photometry gives following magnitudes: J = 5.81+-0.15, H=5.12+-0.15 and Ks=4.61+-0.2.
