IIb형 초신성은 초기 스펙트럼에서 약한 수소선을 가지나요?
A Type IIb supernova has a weak hydrogen line in its initial spectrum, which is why it is classified as a Type II. However, later on the H emission becomes undetectable, and there is also a second peak in the light curve that has a spectrum which more closely resembles a Type Ib supernova. The progenitor could have been a massive star that expelled most of its outer layers, or one which lost most of its hydrogen envelope due to interactions with a companion in a binary system, leaving behind the core that consisted almost entirely of helium. As the ejecta of a Type IIb expands, the hydrogen layer quickly becomes more transparent and reveals the deeper layers.
The classic example of a Type IIb supernova is SN 1993J, while another example is Cassiopeia A. The IIb class was first introduced (as a theoretical concept) by Woosley et al. in 1987, and the class was soon applied to SN 1987K and SN 1993J.
has a weak hydrogen line in its initial spectrum