Spectral Features of KT Eri in its Nebular Phase

Non-spherically symmetric distributions of ejected gas are often observed in classical nova remnants. However, it is unclear if these asymmetries could be produced from nova explosions. Spectra in the nebular phase can provide information on the kinematics of ejected materials. Classical nova KT Eri was discovered on November 2009. It is considered a candidate for a recurrent nova based on the high expansion velocity and rapid decline of its light curve. In order to investigate the velocity field of ejected gas in the system, we performed optical spectroscopic observations from 2010 September to 2010 December at Koyama Astronomical Observatory. We noticed the strong [O III] and He II lines in the spectra on September 1, which suggests that the nova had already entered the nebular phase. It is notable that the [O III] lines showed complex profiles with at least six peaks on September 1. Those features can be de-convolved into four velocity components (-2,000 km s^-1, -1,000 km s^-1, +700 km s^-1, and +1,800 km s^-1) of doublet [O III] λ4959 and λ5007.