Formation of Extremely Low Mass White Dwarf Binaries via a Stable Mass Transfer Channel

Subjects: Astronomy submitted time 2024-01-05 Cooperative journals: 《天文学进展》

LIU Guang-chang, CHEN Hai-liang

Abstract： Extremely low mass white dwarf (ELM WD) binaries are important for studies of binary evolution, common envelope, AM CVn binaries and asteroseismology . Due to their short orbital periods, they are also important gravitational wave sources. However, their formation and evolution is not well understood. By using a newly suggested magnetic braking prescription，modeling the formation and evolution of ELM WD binaries via a stable mass transfer channel. Research presents the initial binary parameter space for the formation of ELM WD binaries and find the He WD masses in these binaries are (0.11 ∼ 0.21) M⊙. In addition, research finds that some extremely low mass white dwarf binaries can evolve into AM CVn binaries within the Universe age and these binaries have He WD masses of (0.14 ∼ 0.16) M⊙. Research also finds that the gravitational wave signal from these binaries can be detected by the space-borne gravitational wave observatories, such as LISA, TianQin, TaiJi. Finally research also discusses the impact of different material accumulation efficiencies on the evolution results of the same binary system, and it finds that it not only significantly affects the final mass of the main star, but also has little impact on the donor star and the evolution process of binary system.

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