2020ApJ...899..162W

We present optical and infrared photometry of the classical nova V906 Car, also known as Nova Car 2018 and ASASSN-18fv, which was discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) on 2018 March 16.32 UT (MJD 58193.0). The nova reached its maximum on MJD 58222.56 at V_max = 5.84 ± 0.09 mag, and had decline times of t_2,V=26.2 days and t_3,V=33.0 days. The data from Evryscope shows that the nova had already brightened to g^′ ≃13 mag five days before discovery, as compared with its quiescent magnitude of g = 20.13 ± 0.03. The extinction toward the nova, as derived from high-resolution spectroscopy, shows an estimate consistent with foreground extinction to the Carina Nebula of A_V=1.11_–0.39^+0.54. The light curve resembles a rare C (cusp) class nova with a steep decline slope of α = -3.94 post-cusp flare. From the light-curve decline rate, we estimate the mass of the white dwarf to be M_WD = <0.8M_☉, consistent with M_WD=0.71_–0.19^+0.23 derived from modeling the accretion disk of the system in quiescence. The donor star is likely a K-M dwarf of 0.23-0.43 M_☉, which is heated by its companion.