Near Infrared studies of the carbon-monoxide and dust forming nova V5668 Sgr

TL;DR

This paper presents near-infrared observations of Nova V5668 Sgr, analyzing its spectral evolution, CO emission, dust formation, and deriving physical parameters such as mass, temperature, and distance, revealing insights into nova outburst processes.

Contribution

It provides detailed NIR spectral analysis of Nova V5668 Sgr, including CO emission modeling, dust properties, and estimates of physical parameters, which are novel for this particular nova.

Findings

CO emission observed with estimated mass and temperature

Dust mass and shell size determined from SED analysis

Distance to nova estimated at 1.54 kpc

Abstract

We present near-infrared (NIR) observations of Nova V5668 Sgr, discovered in outburst on 2015 March 15.634 UT, between 2d to 107d after outburst. NIR spectral features are used to classify it as a FeII class of nova. The spectra follow the evolution of the spectral lines from a P Cygni stage to a pure emission phase where the shape of the profiles suggests the presence of a bipolar flow. A notable feature is the presence of carbon monoxide first overtone bands which are seen in emission. The CO emission is modeled to make estimates of the mass, temperature and column density to be (0.5--2.0)$\times$ 10$^{-8}$ M$_\odot$, 4000 $\pm$ 300K and (0.36--1.94)$\times$ 10$^{19}$ cm$^{-2}$ respectively. The $^{12}$C/$^{13}$C ratio is estimated to be $\sim$ 1.5. V5668 Sgr was a strong dust producer exhibiting the classical deep dip in its optical light curve during dust formation. Analysis of the dust SED yields a dust mass of 2.7 $\times$ 10${^{\rm -7}}$ $M_\odot $, a blackbody angular diameter of the dust shell of 42 mas and a distance estimate to the nova of 1.54 kpc which agrees with estimates made from MMRD relations.