An H I shell-like structure associated with nova V458 Vulpeculae?

Abstract

We report the radio detection of a shell-like H I 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 H I emission, this is a single-velocity component emission with significant clumping at ∼0.5 arcmin scales. The observed narrow-line width of ∼5 km s^-1 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 H i mass of the nebula is about 25 M⊙. However, there are some indications that the system is closer than 13 kpc. If there is a physical association of the H I structure and the nova system, the asymmetric morphology and the off-centred stellar system indicate 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 H I structure associated with a classical nova.