Optical Morphology, Inclination and Expansion Velocity of the Ejected Shell of Nova Monocerotis 2012

TL;DR

This study models the ejected shell of Nova Monocerotis 2012, revealing a bipolar shape with high inclination and velocity, challenging expectations for a system with a main sequence star.

Contribution

It provides the first detailed morphological and kinematic analysis of the nova's ejecta using synthetic spectra fitting, highlighting a bipolar structure with specific inclination and velocity.

Findings

Ejected shell has a bipolar morphology.

Inclination angle is approximately 82 degrees.

Maximum expansion velocity is about 2400 km/s.

Abstract

The morphology of the ejected shell of the He/N Nova Monocerotis 2012 outburst was studied in detail. Synthetic line profile spectra were compared to the [O {\sc iii}] 4959,5007 \AA\ emission line profiles in order to find the best fit morphology, inclination angle and maximum expansion velocity of the ejected shell. The simplest morphology was found to be that of a bipolar structure with an inclination angle of 82$\pm6$ degrees and a maximum expansion velocity of 2400$^{+300}_{-200}$ km/s (at day 130 after outburst). Such a high degree of shaping is un-expected for a system with a main sequence star (as suspected from the systems colors). The degree of shaping may be disentangled with resolved optical imaging. Furthermore, these results may be confirmed with radio imaging which is expected to follow the same gross features of the outburst as the optical band and the high inclination implied here can be corroborated with a 7.1 hour period which has been suggested to arise from partial eclipses of extended emission by an accretion disk rim.