TY - JOUR
T1 - A possible mechanism for wiggling protostellar jets from three-dimensional simulations in a stratified ambient medium
AU - De Gouveia Dal Pino, Elisabete M.
AU - Birkinshaw, Mark
AU - Benz, Willy
PY - 1996/4/1
Y1 - 1996/4/1
N2 - Most collimated supersonic protostellar jets show a collimated wiggling, and knotty structure (e.g., the Haro 6-5B jet) and frequently reveal a long gap between this structure and the terminal bow shock. In a few cases, there is no evidence of such a terminal feature. We present three-dimensional smoothed particle hydrodynamical simulations that suggest that this morphology may be due to the interaction of the propagating cooling jet with a nonhomogeneous ambient medium. In regions where the ambient gas has an increasing density (and pressure) gradient, we find that it tends to compress the cold, low-pressure cocoon of shocked material that surrounds the beam, destroy the bow shock-like structure at the head, and enhance beam focusing, wiggling, and internal traveling shocks. In ambient regions of decreasing density (and pressure), the flow widens and relaxes, becoming very faint. This could explain "invisible" segments in systems like the Haro 6-5B jet. The bow shock in these cases could be a relic of an earlier outflow episode, as previously suggested, or the place where the jet reappears after striking a denser portion of the ambient medium.
AB - Most collimated supersonic protostellar jets show a collimated wiggling, and knotty structure (e.g., the Haro 6-5B jet) and frequently reveal a long gap between this structure and the terminal bow shock. In a few cases, there is no evidence of such a terminal feature. We present three-dimensional smoothed particle hydrodynamical simulations that suggest that this morphology may be due to the interaction of the propagating cooling jet with a nonhomogeneous ambient medium. In regions where the ambient gas has an increasing density (and pressure) gradient, we find that it tends to compress the cold, low-pressure cocoon of shocked material that surrounds the beam, destroy the bow shock-like structure at the head, and enhance beam focusing, wiggling, and internal traveling shocks. In ambient regions of decreasing density (and pressure), the flow widens and relaxes, becoming very faint. This could explain "invisible" segments in systems like the Haro 6-5B jet. The bow shock in these cases could be a relic of an earlier outflow episode, as previously suggested, or the place where the jet reappears after striking a denser portion of the ambient medium.
KW - Hydrodynamics
KW - ISM: jets and outflows
KW - Stars: mass loss
KW - Stars: pre-main-sequence
UR - http://www.scopus.com/inward/record.url?scp=15444378229&partnerID=8YFLogxK
U2 - 10.1086/309978/pdf
DO - 10.1086/309978/pdf
M3 - Article (Academic Journal)
AN - SCOPUS:15444378229
VL - 460
SP - L111-L114
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 2
ER -