The Helium Common-envelope Wind Scenario for SN 2020eyj

Journal article

SN 2020eyj is the first Type Ia supernova (SN Ia) showing the signature of compact helium-rich circumstellar material (CSM). Such a large amount of CSM is difficult to explain in a single-degenerate scenario where the donor star is a helium star. Here we show that, under certain conditions, it is possible that the transfer of helium leads to a common envelope (CE) engulfing the system, similar to the CE wind model proposed by X. Meng & P. Podsiadlowski. If in such a helium CE wind model the initial white dwarf mass is larger than 1.1 M⊙ and the helium star is more massive than 1.8 M⊙, the mass of a helium CE can be larger than 0.3 M⊙ prior to supernova explosion. The CE mass heavily depends on the initial parameters of the binary system. A dynamical CE ejection event could occur shortly before the supernova, and then our model may naturally explain the properties of SN 2020eyj, specifically the massive He-rich CSM, and its dim peak brightness, low ejecta velocity, and low birth rate.

Authors: Meng, X; Podsiadlowski, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 997
• Issue: 1
• Article number: 96
• Publication date: 2026-01-16
• Acceptance date: 2025-12-03
• DOI: 10.3847/1538-4357/ae28da
• EISSN: 1538-4357
• ISSN: 0004637X, 0004-637X
• Language: English
• Keywords: Type Ia supernovae; White dwarf stars; Supernova remnants