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Young A and B stars, the so-called Herbig Ae/Be stars (HAeBe), are surroundedby an active accretion disk and drive outflows. We study the jet HH 409, whichis launched from the HAeBe star HD 163296, using new and archival observationsfrom Chandra and HST/STIS. In X-rays we can show that the central source is notsignificantly extended. The approaching jet, but not the counter-jet, isdetected in Ly alpha. In addition, there is red-shifted Ly alpha emissionextended in the same direction as the jet, that is also absent in thecounter-jet. We can rule out an accretion or disk-wind origin for this feature.In the optical we find the knots B and B2 in the counter-jet. Knot B has beenobserved previously, so we can derive its proper motion of 0.37+-0.01arcsec/yr. Its electron density is 3000/cm^3, thus the cooling time scale is afew months only, so the knot needs to be reheated continuously. The shock speedderived from models of H alpha and forbidden emission lines (FELs) decreasedfrom 50 km/s in 1999 to 30 km/s in 2011 because the shock front loses energy asit travels along the jet. Knot B2 is observed at a similar position in 2011 asknot B was in 1999, but shows a lower ionization fraction and higher mass lossrate, proving variations in the jet launching conditions.

The evolution of the jet from Herbig Ae star HD 163296 from 1999 to 2011