Infrared spectroscopy of the remnant of Nova Sco 2014: a symbiotic star with too little circumstellar matter to decelerate the ejecta

TL;DR

This study confirms Nova Sco 2014 as a symbiotic binary with a cool giant companion, revealing that such novae may not always exhibit ejecta deceleration, challenging previous assumptions.

Contribution

It provides infrared spectral evidence identifying a cool giant star in Nova Sco 2014, establishing it as a symbiotic nova without ejecta deceleration.

Findings

Nova Sco 2014 hosts an M6III giant star.

The nova shows typical symbiotic emission lines.

Ejecta deceleration is not universal in symbiotic novae.

Abstract

Pre-outburst 2MASS and WISE photometry of Nova Sco 2014 (V1534 Sco) have suggested the presence of a cool giant at the location of the nova in the sky. The spectral evolution recorded for the nova did not however support a direct partnership because no flash-ionized wind and no deceleration of the ejecta were observed, contrary to the behavior displayed by other novae which erupted within symbiotic binaries like V407 Cyg or RS Oph. We have therefore obtained an 0.8-2.5 micron spectra of the remnant of Nova Sco 2014 in order to ascertain if a cool giant is indeed present and if it is physically associated with the nova. The spectrum shows the presence of a M6III giant, reddened by E(B-V)=1.20, displaying the typical and narrow emission-line spectrum of a symbiotic star, including HeI 1.0830 $\mu$m with a deep P-Cyg profile. This makes Nova Sco 2014 a new member of the exclusive club of novae that erupt within a symbiotic binary. Nova Sco 2014 shows that a nova erupting witin a symbiotic binary does not always come with a deceleration of the ejecta, contrary to the common belief. Many other similar systems may lay hidden in past novae, expecially in those that erupted prior to the release of the 2MASS all-sky infrared survey, which could be profitably cross-matched now against them.