The Vela Pulsar Wind Nebula: Termination-Shock Pressure Balance in an Old System

This paper computes the energy, density and acceleration budgets of the Vela pulsar wind nebula from a small set of adopted, published input values, using the relations stated in the Methods and a deposited script that reproduces every number. The spin-down power is 6.93e+36 erg per second and the characteristic age 1.13e+04 years, in reasonable agreement with the remnant's age, so the timing clock and the remnant clock can be reconciled without exotic braking. Balancing the wind against a confining pressure of 5 x 10^-11 dyn per square centimetre puts the termination shock at 0.197 parsecs, the scale of the inner X-ray structure, while the wind pressure at the adopted one-parsec nebular edge has fallen to 1.93e-12 dyn per square centimetre. 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.