How much hydrogen is in Type Ib and IIb supernova progenitors?

Abstract

Core-collapse supernovae showing little or no hydrogen (denoted Type IIb and Ib, respectively) are the explosions of massive stars that lost some or most of their outer envelopes. How they lose their mass is unclear, but it likely involves binary interaction. So far, seven progenitors of such supernovae have been identified in pre-explosion imaging (five for Type IIb events and two for Type Ib events). Here we evolve detailed binary stellar evolution models in order to better understand the nature of these progenitors. We find that the amount of hydrogen left in the envelope at the time of explosion greatly depends on the post-interaction mass-loss rate. The leftover hydrogen, in turn, strongly affects progenitor properties, such as temperature and photospheric radius, in non-trivial ways. Together with extinction and distance uncertainties in progenitor data, it is difficult to deduce an accurate progenitor hydrogen mass from pre-explosion imaging. We quantify this uncertainty and find that available data is consistent with the proposed Type Ib -IIb hydrogen mass threshold of 0.033 M (Hachinger et al. 2012) but not with the proposed threshold of 0.001 M (Dessart et al. 2011), implying that even Type Ib progenitors are not pure helium stars. These results alleviate the proposed tension between the Type Ib classification of SN 2019yvr and its candidate progenitor properties (Kilpatrick et al. 2021). We also estimate the brightness of a surviving 2019yvr progenitor companion, which might be detected in future observations.

Updated Photometry of the Yellow Supergiant Progenitor and Late-time Observations of the Type IIb Supernova 2016gkg

“…Subsequent analyses of the same data yielded estimates of 15-20 M (Tartaglia et al 2017) and19.5 M (Bersten et al 2018), with both estimates invoking close binary models to explain the photometry and low hydrogen envelope mass in the progenitor star. However, subsequent analyses using Modules for Experiments in Stellar Astrophysics (MESA) models suggest that for certain mass loss prescriptions there are both single-star and binary systems that can reproduce the pre-explosion photometry (Sravan et al 2018;Gilkis & Arcavi 2021).…”