type Ia supernova


type Ia supernova

[‚tīp ‚wən‚ā ‚sü·pər′nō·və] (astronomy) A member of a subclass of the type I supernovae that brighten relatively smoothly to a maximum whose brightness is relatively uniform among members of the subclass about 2 weeks after the explosion; decline in brightness quasi-exponentially thereafter; show strong lines of silicon, sulfur, calcium, and iron in their peak spectra; have late-time spectra dominated by strong emission lines of iron and cobalt; have line widths that imply velocities from 4000 to 12,000 miles (7000 to 20,000 kilometers) per second, with the highest velocities seen early on; and are believed to be exploding white dwarf stars.