We present four spectra of the Type Ia supernova (SN Ia) 2006D extending from −7 to +13 days with respect to B-band maximum. The spectra include the strongest signature of unburned material at photospheric velocities observed in a SN Ia to date. The earliest spectrum exhibits C II absorption features below 14,000 km s, including a distinctive C II λ6580 absorption feature. The carbon signatures...

We present four spectra of the Type Ia supernova (SN Ia) 2006D extending from −7 to +13 days with respect to B-band maximum. The spectra include the strongest signature of unburned material at photospheric velocities observed in a SN Ia to date. The earliest spectrum exhibits C II absorption features below 14,000 km s, including a distinctive C II λ6580 absorption feature. The carbon signatures...