…continuedA Field Guide to Supernova Spectra
Let's Go to the Zoo!
Below are suites of spectra for different supernovae; to see all five sets of spectra, click here. The following descriptions are largely taken from notes supplied by Filippenko. One should keep in mind that the progenitors of Type II supernovae are heterogeneous, so it's not surprising that their spectra are heterogeneous too.
SN 1994I Taken about 12 days after the explosion, absorptions from calcium, oxygen, and sodium are evident in the original and KAF-0400 spectra. But because of the sensitivity response of the ICX055BL chip, most of these lines are missing from that spectrum. There are no conspicuous lines from helium.
SN 1993J Taken about three days after the explosion, the continuum is essentially featureless in the original. "Features" in the processed spectra result from the response curves of the CCD chips! For a while after a supernova explosion, spectra may exhibit no obvious details.
SN 1994Y Taken about 30 days after the explosion, this spectrum sports several emission lines but no absorptions. Three members of the hydrogen Balmer series are evident; a neutral helium line is also apparent in the spectrum.
SN 1987A Taken about seven days after the explosion, the spectrum of the most famous modern supernova contains strong features due to hydrogen. These lines exhibit so-called P-Cygni profiles, due to rapidly expanding gas, with emissions being bordered by blueshifted absorptions. SN 1987A evolved quickly; typical Type II supernovae wouldn't show such strong lines until later.