Ionized mass and linear radius of nova remnants of theoretical CNe for 1.25 M_⊙ (magenta) and 1.40 M_⊙ (red) WDs of different temperatures (Yaron et al. 2005) as labeled in the top-left panel of Fig. 6. The solid line corresponds to the ionized mass to distance relationship of 0.061 × (D/1kpc)^5/2 M_⊙ derived for HaTr5 based on its intrinsic Hα flux, angular diameter, and filling factor (Eq. (3)). Models requiring ISM density above 20 cm⁻³ are marked as open symbols.