AT 2019qyl in NGC 300: Early Outflow Collisions for a Very Fast Nova in a Symbiotic Binary∗†

Nova eruptions, thermonuclear explosions on the surfaces of white dwarfs (WDs), are now recognized to be among the most common shock-powered transients. We present the early discovery and rapid ultraviolet (UV), optical, and infrared (IR) temporal development of AT 2019qyl, a recent nova in NGC 300. The light curve shows a rapid rise lasting . 1 day, reaching a peak absolute magnitude of MV = −9.2 mag, and a very fast decline, fading by 2 mag over 3.5 days. A steep drop-off in the light curves after 71 days and the rapid decline timescale suggest a low-mass ejection from a massive WD with MWD & 1.2 M . We present an unprecedented view of the early spectroscopic evolution of such an event. Three spectra prior to the peak reveal a complex, multi-component outflow giving rise to Corresponding author: Jacob E. Jencson jjencson@email.arizona.edu ∗ This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. † Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. ar X iv :2 10 2. 11 29 1v 1 [ as tr oph .S R ] 2 2 Fe b 20 21