SIMBAD references

AM Canum Venaticorum (AM CVn) binaries consist of a degenerate helium donor and a helium, C/O, or O/Ne white dwarf accretor, with accretion rates of {dot}M = 10^–13 - 10^–5 M☉/yr. For accretion rates <10^–6 M_☉/yr, the accreted helium ignites unstably, resulting in a helium flash. As the donor mass and {dot}M decrease, the ignition mass increases and eventually becomes larger than the donor mass, yielding a "last-flash" ignition mass of ≲0.1 M_☉. Bildsten et al. have predicted that the largest outbursts of these systems will lead to dynamical burning and thermonuclear supernovae. In this paper, we study the evolution of the He-burning shells in more detail. We calculate maximum achievable temperatures as well as the minimum envelope masses that achieve dynamical burning conditions, finding that AM CVn systems with accretors ≳0.8 M_☉ will undergo dynamical burning. Triple-α reactions during the hydrostatic evolution set a lower limit to the ¹²C mass fraction of 0.001-0.05 when dynamical burning occurs, but core dredge-up may yield ¹²C, ¹⁶O, and/or ²⁰Ne mass fractions of ∼0.1. Accreted ¹⁴N will likely remain ¹⁴N during the accretion and convective phases, but regardless of ¹⁴N's fate, the neutron-to-proton ratio at the beginning of convection is fixed until the onset of dynamical burning. During explosive burning, the ¹⁴N will undergo ¹⁴N(α, γ)¹⁸F(α, p)²¹Ne, liberating a proton for the subsequent ¹²C(p, γ)¹³N(α, p)¹⁶O reaction, which bypasses the relatively slow α-capture onto ¹²C. Future hydrodynamic simulations must include these isotopes, as the additional reactions will reduce the Zel'dovich-von Neumann-Döring length, making the propagation of the detonation wave more likely.