We investigate the properties of Fe-rich knots on the east limb of the Cassiopeia A supernova remnant using observations with Chandra/ACIS and analysis methods developed in a companion paper .
We use the fitted ionization age and electron temperature of the knots to constrain the ejecta density profile and the Lagrangian mass coordinates of the knots .
Fe-rich knots which also have strong emission from Si , S , Ar , and Ca are clustered around mass coordinates q \simeq 0.35 - 0.4 in the shocked ejecta ; for ejecta mass 2 M _ { \sun } , this places the knots 0.7 - 0.8 M _ { \sun } out from the center ( or 2 - 2.1 M _ { \sun } , allowing for a 1.3 M _ { \sun } compact object ) .
We also find an Fe clump that is evidently devoid of line emission from lower mass elements , as would be expected if it were the product of \alpha -rich freeze out ; the mass coordinate of this clump is similar to those of the other Fe knots .