Multiwavelength Photometry and Progenitor Analysis of the Nova V906 Car

Abstract

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 days and days. The data from Evryscope shows that the nova had already brightened to 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 . 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  = <0.8 M ⊙ , consistent with 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 , which is heated by its companion.