sample. First, we split the sample by phase. Since the velocity of SN features typically decreases monotonically with time because of the receding photosphere, one expects lower velocity features at later times. The phase-split median spectra do not appear to be significantly different from each other or the median spectrum from the full sample. This is likely the result of the sample having a very narrow phase range.

We also split the sample by light-curve shape. We split the sample by $s = 1.01$ to match what was done by . Here, we see the same result that found and shows in their Figures 5 and 7. Namely, the low-stretch (corresponding to faster-declines and lower luminosity) SNe have narrower, seemingly lower velocity features than those of high-stretch SNe.

![image](dgauss_spec){width="6.8in"}

Given the above difference, it is worth a detailed look at the line profiles. Despite coming from P-Cygni profiles, the line profiles appear to be similar to the sum of two Gaussians, and performing such a fit resulted in excellent matches to the profiles. The absorption component of a P-Cygni profile is very similar to a Gaussian, so using Gaussians to fit the absorption is a reasonable choice. In Figure \[f:dgauss\], 