Infrared studies of Nova Scorpii 2014: an outburst in a symbiotic system sans an accompanying blast wave

TL;DR

This study presents near-IR spectroscopy of Nova Scorpii 2014, revealing its occurrence in a rare symbiotic binary system, with spectral features indicating a possible recurrent nova, but lacking expected gamma-ray signatures and shock deceleration evidence.

Contribution

It provides detailed near-IR spectral analysis of Nova Sco 2014, identifying its symbiotic nature and discussing its classification and peculiarities compared to similar systems.

Findings

Nova Sco 2014 occurred in a symbiotic binary system.

Spectra are typical of He/N class novae with broad emission lines.

No gamma-ray emission or shock deceleration signatures were observed.

Abstract

Near-IR spectroscopy is presented for Nova Scorpii 2014. It is shown that the outburst occurred in a symbiotic binary system - an extremely rare configuration for a classical nova outburst to occur in but appropriate for the eruption of a recurrent nova of the T CrB class. We estimate the spectral class of secondary as M5III $\pm$ (two sub-classes). The maximum magnitude versus rate of decline (MMRD) relations give an unacceptably large value of 37.5 kpc for the distance. The spectra are typical of the He/N class of novae with strong HeI and H lines. The profiles are broad and flat topped with full width at zero intensities (FWZIs) approaching 9000-10000 km s$^{-1}$ and also have a sharp narrow component superposed which is attributable to emission from the giant's wind. Hot shocked gas, accompanied by X-rays and $\gamma$ rays, is expected to form when the high velocity ejecta from the nova plows into the surrounding giant wind. Although X-ray emission was observed no $\gamma$-ray emission was reported. It is also puzzling that no signature of a decelerating shock is seen in the near-infrared (NIR), seen in similar systems like RS Oph, V745 Sco and V407 Cyg, as rapid narrowing of the line profiles. The small outburst amplitude and the giant secondary strongly suggest that Nova Sco 2014 could be a recurrent nova.