Six months of mass outflow and inclined rings in the ejecta of V1494 Aql

Abstract

V1494 Aql was a very fast nova which reached a visual maximum of about 4.0 by the end of 1999 December 3. We report observations from 4 to 284 days after discovery, including sub-mm- and cm-band fluxes, a single MERLIN image, and optical spectroscopy in the 410 to 700 nm range. The extent of the radio continuum emission is consistent with a recent lower distance estimate of 1.6 kpc. We conclude that the optical and radio emission arises from the same expanding ejecta. We show that these observations are not consistent with simple kinematical spherical shell models used in the past to explain the rise and fall of the radio flux density in these objects. The resolved remnant structure is consistent with an inclined ring of enhanced density within the ejecta. Optical spectroscopy indicates likely continued mass ejection for over 195 days, with the material becoming optically thin in the visible sometime between 195 and 285 days after outburst.