Near-Infrared spectroscopy of Nova Sco 2016 (PNV J17381927-3725077)

ATel #9162; Mudit Srivastava, D. P. K. Banerjee, N. M. Ashok, Vishal Joshi (Astronomy and Astrophysics Division, Physical Research Laboratory, India)
on 17 Jun 2016; 09:04 UT
Credential Certification: Dipankar P.K. Banerjee (orion@prl.res.in)

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Near-infrared observations are reported of Nova Sco 2016 detected in outburst on 10.629 June 2016 (CBET 4285). A classification of the nova as a Fe II or He/N type was not suggested from its optical spectrum (CBET 4285). We obtained a near-IR spectrum on 2016 June 16.82 with the 1.2m Mount Abu telescope in the 0.9-2.4 micron region at a resolution of ~ 1000 using the NICS imager-spectrograph. The spectrum is a text-book example of a Fe II nova in the early stages. Most of the standard Brackett and Paschen HI lines and CI & OI lines seen in the NIR spectra of Fe II novae (spectral templates are given in Banerjee and Ashok, BASI, 40, 243) are present. The HeI 1.0831 micron line is also weakly present. P-Cygni profiles are seen; the velocity separation between emission peak and absorption minimum of the Paschen beta 1.2818 micron line is ~ 1700 km/s. The FWHM of the HI lines are typically 1350-1450 km/s. No first overtone CO emission is presently seen. However, dust formation is still likely in this nova as evinced by the presence of several low excitation lines of Na and Mg -- these lines are good predictors of dust formation in the future (Das et al. 2008, MNRAS, 391, 1874). Preliminary analysis of the NIR photometry of 2016 June 16.8 gives J = 8.35+-0.06, H= 8.04+-0.03 and K = 7.72+-0.05. From the 2MASS field images, a potential progenitor of the nova could be the 2MASS star J17381931-3725087 ( J=14.82, H=13.89, K= 13.56) which has RA and declination end figures of 19.32s and 8.77s which are close to the nova end figures of 19s.22, 07".8 reported in CBET 4285. However the 2MASS field appears to show faint, multiple stellar sources at the nova's position, so it is difficult to be certain.