Type Ia supernova SN 2003du: Optical observations

¹ Indian Institute of Astrophysics, II Block Koramangala, Bangalore 560 034, India e-mail: gca@iiap.res.in
² Center for Research and Education in Science & Technology, Hosakote e-mail: dks@crest.ernet.in

Received: 19 July 2004
Accepted: 15 September 2004

Abstract

photometry and optical spectra of type Ia supernova SN 2003du obtained at the Indian Astronomical Observatory for nearly a year since discovery are presented. 
The apparent magnitude at maximum was  mag, and the colour  mag. The luminosity decline rate,  mag indicates an absolute B magnitude at maximum of  mag and the distance modulus to the parent galaxy as . The light curve shapes are similar, though not identical, to those of SNe 1998bu and 1990N, both of which had luminosity decline rates similar to that of SN 2003du and occurred in spiral galaxies. The peak bolometric luminosity indicates that ~ mass of ⁵⁶Ni was ejected by the supernova. The spectral evolution and the evolution of the Si II and Ca II absorption velocities closely follows that of SN 1998bu, and in general, is within the scatter of the velocities observed in normal type Ia supernovae.
The spectroscopic and photometric behaviour of SN 2003du is quite typical for SNe Ia in spirals.
A high velocity absorption component in the Ca II (H and K) and IR-triplet features, with absorption velocities of ~ km s^-1 and ~ km s^-1 respectively, is detected in the pre-maximum spectra of days -11 and -7.