NIR spectra of Nova V1674 Herculis

This fastest nova on record displays a rich emission line spectrum, including strong coronal line emission with complex structures. The hydrogen line fluxes, combined with a distance of 4.7_-1.0_^+1.3^kpc, give an upper limit to the hydrogen ejected mass of M_ej_=1.4_-1.2_^+0.8^x10^-3^M_{sun}_.

The coronal lines appeared at day 11.5, the earliest onset yet observed for any classical nova, before there was an obvious source of ionizing radiation. We argue that the gas cannot be photoionized, at least in the earliest phase, and must be shocked. Its temperature is estimated to be 105.57+/-0.05K on day 11.5.