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Paper: Late-Phase Observations of a Super-Chandrasekhar SN Ia
Volume: 458, Galactic Archaeology: Near-Field Cosmology and the Formation of the Milky Way
Page: 49
Authors: Yamanaka, M.; Kawabata, K. S.; Maeda, K.; Tanaka, M.; Yoshida, M.; Hattori, T.; Nomoto, K.; Komatsu, T.; Okushima, T.
Abstract: A super-Chandrasekhar (SC) supernova (SN) has an extremely high luminosity and a slow decline rate of the light curve in the early-phase. We present late-phase observations of a SC SN 2009dc. We find that optical luminosity at a year after maximum is much fainter than that expected from its early luminosity. We attempt to fit the analytic light curve model to the observations using Arnett's rule. The model successfully explains the light curves until 120 days. This suggests that the extremely high luminosity originates from the 56Ni decay. We suggest that the late-phase decline would be caused by the dust formation. The existence of strong carbon features in early-phase spectra would support this scenario. We also find the blend of [Ca II] and [Ni II] in its late-phase spectrum. This indicates that the calcium is distributed in the inner layer as nickel and iron. We conclude that the mixing may occur in inner-part of the ejecta.
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