Shocks and Ejecta Mass: Radio Observations of Nova V1723 Aql

TL;DR

This study uses advanced radio observations of Nova V1723 Aql to investigate ejecta mass and shock phenomena, revealing complexities in nova shell evolution and challenging simple models of ejecta expulsion.

Contribution

It provides detailed, long-term radio data that uncover shock-related features and refine estimates of ejecta mass, improving understanding of nova explosion mechanisms.

Findings

Detection of a shock-related bump in radio light curve

Ejecta mass estimates are lower than previous models

Identification of complex density profiles in nova shells

Abstract

The radio light curves of novae rise and fall over the course of months to years, allowing for detailed observations of the evolution of the nova shell. However, the main parameter determined by radio models of nova explosions - the mass of the ejecta - often seems to exceed theoretical expectations by an order of magnitude. With the recent technological improvements on the Karl G. Jansky Very Large Array (VLA), new observations can test the assumptions upon which ejecta mass estimates are based. Early observations of the classical nova V1723 Aql showed an unexpectedly rapid rise in radio flux density and a distinct bump in the radio light curve on the rise to radio maximum, which is inconsistent with the simple model of spherical ejecta expelled in a single discrete event. This initial bump appears to indicate the presence of shocked material in the outer region of the ejected shell, with the emission from the shocks fading over time. We explore possible origins for this emission and its relation to the mass loss history of the nova. The evolution of the radio spectrum also reveals the density profile, the mass of the ejected shell, and other properties of the ejecta. These observations comprise one of the most complete, longterm set of multi-wavelength radio observations for any classical nova to date.