We use photoionization modeling to assess the binary nature of the central stars of NGC 2392 and NGC 6026 .
If they are close binaries , they are potential Type Ia supernova ( SN Ia ) progenitors if the total mass exceeds the Chandrasekhar limit .
We show that the nucleus of NGC 2392 likely has a hot , massive ( \simeq 1 M _ { \odot } ) white dwarf companion , and a total mass of \sim 1.6 M _ { \odot } , making it an especially interesting system .
The binary mass in NGC 6026 is less , \sim 1.1 M _ { \odot } .
Even though its orbital period is short , it is not considered to be a SN Ia progenitor .