Extended Data Fig. 1: Spectral visualization of potential WN+WO binaries or chance alignments.
From: Discovery of a transitional type of evolved massive star with a hard ionizing flux
Upper panel (a): Comparison of the normalized optical spectrum of M33WR 206 with those of the WN2-star WR 2 and the WO-star WR 142. To check whether the unique appearance of M33WR 206 could also be the product of a WN and WO star, we show two weighted combinations of the latter two stars with the WN2-star providing either 80 % (dash-dotted line) or 95 % (dotted line) of the flux to the optical spectrum. In either case, unobserved features appear with the most prominent ones being highlighted in the figure. Lower panel (b): Similar comparison, but now using the WN4 star WR 6 as the WN component, illustrating that for cooler WN subtypes even more additional features would appear.
