2017MNRAS.470L..72L

Hydrodynamical simulations predict that a large amount of hydrogen (>=0.1 M_☉) is removed from a hydrogen-rich companion star by the SN explosion in the single-degenerate scenario of Type Ia supernovae (SNe Ia). However, non-detection of hydrogen-rich material in the late-time spectra of SNe Ia suggests that the hydrogen mass stripped from the progenitor system is <=0.001-0.058 M_☉. In this Letter, we include thermohaline mixing into self-consistent binary evolution calculations for the helium-enriched main-sequence (HEMS) donor channel of SNe Ia for the first time. We find that the swept-up hydrogen masses expected in this channel are around 0.10-0.17 M_☉, which is higher than the observational limits, although the companion star is strongly helium-enriched when the SN explodes. This presents a serious challenge to the HEMS donor channel.