$\star$ Spectral evolution

As we saw in chapter 5 , an evolution of the metalicity could involve modifications in the spectrum and the luminosity of the supernovæ. However, the many spectroscopic observations of supernovæ until redshifts around 1 did not make it possible, to date, to highlight such an evolution.

Figure 6.4 shows the comparison between the spectra of supernovæ close and 1997ap which with a redshift of 0.83. No notable difference is discernible between 1997ap and its congeneric close relations.

Appear: Comparison of the spectra of supernovæ close and 1997ap which with a shift towards the red to 0.83. These spectra are brought back in the reference frame of 1997ap. This figure is drawn from perlmutter1998.