The Cassiopeia A supernova was of type IIb.
Cassiopeia A is the youngest supernova remnant known in the Milky Way and a unique laboratory for supernova physics. We present an optical spectrum of the Cassiopeia A supernova near maximum brightness, obtained from observations of a scattered light echo more than three centuries after the direct light of the explosion swept past Earth. The spectrum shows that Cassiopeia A was a type IIb supernova and originated from the collapse of the helium core of a red supergiant that had lost most of its hydrogen envelope before exploding. Our finding concludes a long-standing debate on the Cassiopeia A progenitor and provides new insight into supernova physics by linking the properties of the explosion to the wealth of knowledge about its remnant.
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany. krause@mpia.de
Oliver
O
Krause
Stephan M
SM
Birkmann
Tomonori
T
Usuda
Takashi
T
Hattori
Miwa
M
Goto
George H
GH
Rieke
Karl A
KA
Misselt