Supernova - Classification | Technology Trends

Classification

As part of the attempt to understand supernovae, astronomers have classified them according to their light curves and the absorption lines of different chemical elements that appear in their spectra. The first element for division is the presence or absence of a line caused by hydrogen. If a supernova's spectrum contains lines of hydrogen (known as the Balmer series in the visual portion of the spectrum) it is classified Type II; otherwise it is Type I. In each of these two types there are subdivisions according to the presence of lines from other elements or the shape of the light curve (a graph of the supernova's apparent magnitude as a function of time).

Supernova taxonomy
Type I No hydrogen	Type Ia Presents a singly ionized silicon (Si II) line at 615.0 nm (nanometers), near peak light
	Type Ib/c Weak or no silicon absorption feature	Type Ib Shows a non-ionized helium (He I) line at 587.6 nm
		Type Ic Weak or no helium
Type II Shows hydrogen	Type II-P/L/N Type II spectrum throughout	Type II-P/L No narrow lines	Type II-P Reaches a "plateau" in its light curve
			Type II-L Displays a "linear" decrease in its light curve (linear in magnitude versus time).
		Type IIn Some narrow lines
	Type IIb Spectrum changes to become like Type Ib