The structure of a recent nova shell as observed by ALMA

TL;DR

This paper presents high-resolution ALMA observations of a recent nova shell, revealing the smallest structures ever observed in a stellar explosion remnant, with detailed insights into its ionised gas distribution.

Contribution

It provides the first detailed imaging of tiny clumps in a nova shell, highlighting the structure and density of the ionised gas at unprecedented resolution.

Findings

Detection of 10^15 cm scale clumps in the nova shell

Peak hydrogen densities reach 10^6 cm^-3 in the clumps

Large-scale structures may be due to unresolved condensations

Abstract

High resolution ALMA observations of the recent (2.52 yrs old) shell of Nova V5668 Sgr (2015) show a highly structured ionised gas distribution with small (10$^{15}$ cm) clumps. These are the smallest structures ever observed in the remnant of a stellar thermonuclear explosion. No extended contiguous emission could be found above the 2.5 $\sigma$ level in our data, while the peak hydrogen densities in the clumps reach 10$^6$ cm$^{-3}$. The millimetre continuum image suggests that large scale structures previously distinguished in other recent nova shells may result from the distribution of bright unresolved condensations.