Abstract
We have used three epochs of red [S II] and Hα Hubble Space Telescope (HST) archival images of HH 47 to determine the proper motion velocities of the knots along the jet. With the three available epochs we compute two sets of proper motions (one using the first two epochs, and the second one using the last two epochs). Somewhat surprisingly, we find that the [S II] proper motion velocities show a significant decrease as a function of increasing time. The knots present decelerations of up to ≈50% over the 14 years covered by the three epochs of HST images. This rather dramatic effect might be a result of a variable ejection direction (which would be consistent with the sinuous morphology of the HH 47 jet), leading to the direct interaction of the knots with the surrounding environment.
