Early Infrared and Visible Spectra from the 2022 Outburst of the Recurrent Novae U Scorpii

Abstract

Spectroscopy from 0.46–2.5 μm is presented for the 2022 outburst of the recurrent nova U Scorpii from 2.54, 3.60, and 8.59 days after maximum light. During this period the spectra evolved from comparatively low excitation to the verge of displaying coronal lines. Between days 2.54 and 3.60, the nova showed a marked decrease in the low excitation lines of N i, O i, and Mg ii , an increase in He i, the emergence of N iii, and changes to the very broad line profiles. By day 8.59, the He i lines had been largely replaced by He ii emission and most broad component were weak or undetectable. No optical coronal lines were observed during or immediately following the detection of infrared coronal lines by Banerjee et al.