Fig. 2: Low-resolution optical spectrum of [HP99] 159.
From: A helium-burning white dwarf binary as a supersoft X-ray source
Flux-normalized optical spectrum taken with the SALT/RSS spectrograph on 14 August 2020 at 03:44 UT (mid-time of 1,200 s exposure), with the main emission lines labelled (‘bkg’ labels residuals of removing sky lines). The three absorption features apart from the B-band are also a result of residuals of sky-line removal. The insets demonstrate that the 4,860-Å and 6,560-Å lines result from He II and not hydrogen.
