Light-curve analysis of neon novae

We analyzed light curves of five neon novae, QU Vul, V351 Pup, V382 Vel, V693 CrA, and V1974 Cyg, and determined their white dwarf (WD) masses and distance moduli on the basis of theoretical light curves composed of free–free and photospheric emission. For QU Vul, we obtained a distance of d ∼ 2.4 kpc, reddening of E(B − V) ∼ 0.55, and WD mass of M_WD = 0.82–$0.96M_{\odot }$. This suggests that an oxygen–neon WD lost a mass of more than $\sim 0.1M_{\odot }$ since its birth. For V351 Pup, we obtained $d\sim 5.5kpc$, $E(B-V)\sim 0.45$, and $M_{WD}=0.98$–$1.1M_{\odot }$. For V382 Vel, we obtained $d\sim 1.6kpc$, $E(B-V)\sim 0.15$, and $M_{WD}=1.13$–$1.28M_{\odot }$. For V693 CrA, we obtained $d\sim 7.1kpc$, $E(B-V)\sim 0.05$, and $M_{WD}=1.15$–$1.25M_{\odot }$. For V1974 Cyg, we obtained $d\sim 1.8kpc$, $E(B-V)\sim 0.30$, and $M_{WD}=0.95$–$1.1M_{\odot }$. For comparison, we added the carbon–oxygen nova V1668 Cyg to our analysis and obtained $d\sim 5.4kpc$, $E(B-V)\sim 0.30$, and $M_{WD}=0.98$–$1.1M_{\odot }$. In QU Vul, photospheric emission contributes 0.4–0.8 mag at most to the optical light curve compared with free–free emission only. In V351 Pup and V1974 Cyg, photospheric emission contributes very little (0.2–0.4 mag at most) to the optical light curve. In V382 Vel and V693 CrA, free–free emission dominates the continuum spectra, and photospheric emission does not contribute to the optical magnitudes. We also discuss the maximum magnitude versus rate of decline relation for these novae based on the universal decline law.