Suntzeff also reports that spectrophotometry (obtained as above) of SN 1997dd leads Phillips and himself to deduce this object to be a peculiar type-II supernova. H-alpha is clearly present but weak, and the redward emission is particularly weak. H-beta is extremely weak. Strong Ca II absorption at 390 and 840 nm is present, as is the absorption feature (Na I/He) at 580 nm. The spectrum appears to be intermediate between types II-P and Ib, and it is very similar to the spectrum SN 1987K, 7-9 days after maximum. SN 1997dd is thus expected to evolve rapidly into a type- Ib/c supernova.
International Astronomical Union Circular
- Pub Date:
- August 1997