A 3-mode variable ejection velocity, precessing jet model for HH 30

0 v 1 2 5 A ug 1 99 8 A 3 - mode , variable velocity jet model for HH 34

Variable ejection velocity jet models can qualitatively explain the appearance of successive working surfaces in Herbig-Haro (HH) jets. This paper presents an attempt to explore which features of the HH 34 jet can indeed be reproduced by such a model. From previously published data on this object, we find evidence for the existence of a 3-mode ejection velocity variability, and then explore the...

The Transverse Velocity Structure of the Hh 111 Jet 1

A Pulsed, Precessing Jet in Cepheus A

We present near-infrared H2, radio CO, and thermal infrared observations of the nearby massive star-forming region Cepheus A (Cep A). From H2 bow shocks arranged along four distinct jet axes, we infer that the massive protostellar source HW2 drives a pulsed, precessing jet that has changed its orientation by about 45 in roughly 104 years. The current HW2 radio jet represents the most recent eve...

Theoretical interpretation of the apparent deceleration in the HH 34 superjet

The HH 34 superjet shows a steep velocity decrease (from ∼ 500 to ∼ 100 km s−1) over a distance of ∼ 2 pc on either side of the central source. We explore whether or not this behaviour could be interpreted as evidence for a slow “turning on” of the ejection velocity of the jet, and find that this is indeed possible, but only for an ejection velocity that has had a dramatic growth over the last ...

The physical properties of the HH 30 jet from HST and ground–based data

We investigate the physical properties of the HH 30 jet by applying the spectroscopic diagnostic technique described in Bacciotti & Eislöffel (1999) to ground-based spectra and Hubble Space Telescope (HST) calibrated emission-line images. We derive the variation along the beam of the ionization fraction xe, of the total hydrogen density nH and of the average excitation temperature Te, with a sp...