Puppis A: An Expansion Budget for a Remnant Crossing a Density Gradient

This paper computes the energy, density and acceleration budgets of Puppis A from a small set of adopted, published input values, using the relations stated in the Methods and a deposited script that reproduces every number. At the adopted mean density the Sedov energy is 1.15 in units of 10^51 erg, a factor 1.15 of canonical, so the global budget needs no unusual explosion despite the remnant's brightness, which is a density effect rather than an energy effect. The mean shock speed is 1.32e+03 km/s with a corresponding temperature of 2.08 keV, values that bracket the limb measurements: the stalled eastern shock lies below them and the free western shock above. The calculation is a computation from stated assumptions, not a measurement, and each headline result is reported together with the diagnostic that tests whether the assumed evolutionary phase applies to this object.