A cool and inflated progenitor candidate for the Type Ib supernova 2019yvr at 2.6 yr before explosion

ABSTRACT We present Hubble Space Telescope imaging of a pre-explosion counterpart to SN 2019yvr obtained 2.6 yr before its explosion as type Ib supernova (SN Ib). Aligning post-explosion Gemini-S/GSAOI image, we demonstrate that there is single source consistent with being the progenitor system, second candidate after iPTF13bvn. also analysed Spitzer/Infrared Array Camera (IRAC) imaging, but do not detect any counterparts at location. was highly reddened, and comparing spectra photometry those other, less extinguished SNe derive $E(B-V)=0.51\substack{+0.27\\ -0.16}$ mag for 2019yvr. Correcting dust reddening, determine this log (L/L?) = 5.3 ± 0.2 $T_{\mathrm{eff}} 6800\substack{+400\\ -200}$ K star. This relatively cool photospheric temperature implies radius 320$\substack{+30\\ -50}~\mathrm{ R}_{\odot}$, much larger than expectations stars trace amounts hydrogen in agreement previously identified IIb systems. The system binary star models undergo common envelope evolution, leading primary mass mostly depleted still seemingly conflict classification had signatures strong circumstellar interaction late-time (>150 d) so consider eruptive mass-loss evolution scenarios explain spectroscopic class, counterpart, dense material. hypothesize apparent inflation could be caused by quasi-photosphere formed an extended, low-density envelope, or matter around