2007A&A...469..645S

We present a study of the optical and near-infrared (NIR) properties of the Type Ia Supernova (SNIa) 2003du. An extensive set of optical and NIR photometry and low-resolution long-slit spectra was obtained using a number of facilities. The observations started 13 days before B-band maximum light and continued for 480 days with exceptionally good time sampling. The optical photometry was calibrated through the S-correction technique. The UBVRIJHK light curves and the color indices of SN2003du closely resemble those of normal SNeIa. SN2003du reached a B-band maximum of 13.49±0.02mag on JD2452766.38±0.5. We derive a B-band stretch parameter of 0.988±0.003, which corresponds to Δm₁₅=1.02±0.05, indicative of a SNIa of standard luminosity. The reddening in the host galaxy was estimated by three methods, and was consistently found to be negligible. Using an updated calibration of the V and JHK absolute magnitudes of SNeIa, we find a distance modulus µ=32.79±0.15 mag to the host galaxy, UGC 9391. We measure a peak uvoir bolometric luminosity of 1.35(±0.20)x10⁴³erg/s and Arnett's rule implies that M56^Ni_{≃0.68±0.14M}☉_ of [][56]Ni was synthesized during the explosion. Modeling of the uvoir bolometric light curve also indicates M56^Ni_ in the range 0.6-0.8M_☉. The spectral evolution of SN2003du at both optical and NIR wavelengths also closely resembles normal SNeIa. In particular, the SiII ratio at maximum R(SiII)=0.22±0.02 and the time evolution of the blueshift velocities of the absorption line minima are typical. The pre-maximum spectra of SN2003du showed conspicuous high-velocity features in the CaII H&K doublet and infrared triplet, and possibly in SiIIλ6355, lines. We compare the time evolution of the profiles of these lines with other well-observed SNeIa and we suggest that the peculiar pre-maximum evolution of SiIIλ6355 line in many SNeIa is due to the presence of two blended absorption components.