An HI shell-like structure associated with nova V458 Vulpeculae?

TL;DR

This paper reports the discovery of a shell-like HI structure near nova V458 Vul, suggesting a possible interaction between the nova's past mass loss and the interstellar medium, with detailed kinematic analysis using radio observations.

Contribution

It presents the first detailed kinematic study of an HI shell associated with a nova, highlighting its cold gas composition and potential interaction history.

Findings

Detected a shell-like HI structure near V458 Vul

The HI shell is mostly cold gas with narrow line width

Indications of interaction with the interstellar medium

Abstract

We report the radio detection of a shell-like HI structure in proximity to, and probably associated with, the nova V458 Vul. High spectral resolution observation with the Giant Metrewave Radio Telescope has made it possible to study the detailed kinematics of this broken and expanding shell. Unlike the diffuse Galactic HI emission, this is a single velocity component emission with significant clumping at ~ 0.5' scales. The observed narrow line width of ~ 5 km/s suggests that the shell consists of mostly cold gas. Assuming a distance of 13 kpc to the system, as quoted in the literature, the estimated HI mass of the nebula is about 25 M_sun. However, there are some indications that the system is closer than 13 kpc. If there is a physical association of the HI structure and the nova system, the asymmetric morphology and the off-centred stellar system indicates past strong interaction of the mass loss in the asymptotic giant branch phase with the surrounding interstellar medium. So far, this is the second example, after GK Per, of a large HI structure associated with a classical nova.