Shock excitation of the knots of Hen 3-1475

Abstract

We present new optical STIS HST spectroscopic observations of the jets of the proto-planetary nebula Hen3-1475. The excitation conditions of the knots of Hen3-1475

are derived from the observed optical spectra, confirming that the knots are shock excited.

The shocked spectra are qualitatively reproduced by simple "3/2"Dbow shock models.

We present aset of bow shock models devoted to planetary nebulae, and discuss the effects of the pre-ionization conditions, the bow shock velocity, the bow shock shape and the chemical abundances on the predicted spectra.

To explore the reliability of the "3/2"Dbow shock models, we also compare the observed spectra of other three proto-planetary nebulae(M1-92, M2-56 and CRL618) to the predicted spectra.