I can't stand football https://www.shopgt.com/index.php/stmap_18bcre9.html medchempharmacy.com Prior to 1985, supernovae were either placed into one of two categories – Type I or Type II. This distinction was made based upon the absorption lines that manifested in its spectrum. Type I was then later subdivided into Type Ia and Type Ib. Type Ib supernovae is a category of stellar explosion, which demonstrates helium absorption at a rest wavelength of 5876 angstroms, but lacks an absorption line for silicon and hydrogen.