Core-degenerate SNIP model favored over double-detonation for SNR 0509-67.5 morphology

{"Soker re-examines X-ray and optical data on the LMC remnant and shows that multiple edge asymmetries exist, undermining the claim that a single companion shadow explains the northeast flattening. Circumstellar material from a prior planetary nebula phase accounts for the observed structures without requiring a surviving binary companion.","The reported bulk velocity of iron-rich ejecta, previously attributed to orbital motion in the DDet scenario, is reinterpreted as a natural outcome of asymmetric nickel production in an off-center deflagration-to-detonation transition within a single white dwarf. This removes the kinematic necessity for a close companion.","The critique aligns with emerging evidence that many normal Type Ia events occur inside old planetary nebulae, implying that circumstellar shaping must be included in late-time SNR modeling. If confirmed, this shifts the fraction of SNIPs upward and reduces reliance on double-detonation channels for cosmological standardization.","Next steps require deep narrow-band imaging and high-resolution spectroscopy to map circumstellar density gradients and search for any faint companion remnant; non-detection above current limits within two years would strengthen the SNIP interpretation."}