Multiple outflow episodes from protostars: Three-dimensional models of intermittent jets

Abstract

view Abstract Citations (57) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Multiple Outflow Episodes from Protostars: Three-dimensional Models of Intermittent Jets de Gouveia dal Pino, Elisabete M. ; Benz, Willy Abstract Short abstract: We present fully 3-D simulations of supersonic, radiatively cooling intermittent jets with intermediate and long variability periods (that is, periods of the order of or longer than, the dynamical time scale of the jet). Variations of intermediate period elucidate the formation and evolution of chains of internal regularly spaced radiative shocks, which in this work are identified with the observed emission knots of protostellar jets. Variations of long period elucidate the formation of multiple bow shock structures separated by long trails of diffuse gas, which resemble those observed in systems like HH111 and HH46/47. The time variability of the outflow is probably associated with observed irruptive events in the accretion process around the protostars. In our simulations, the outflow variations are produced by periodically turning on the outflow with a highly supersonic velocity and periodically turning off it to a low velocity regime. In the case of velocity variations of intermediate period, we find, as in previous work, that the shock structures form a train of regularly spaced emitting features which move away from the source with a velocity close to that of the outflow, have high radial motions, and produce low intensity spectra, as required by the observations. As they propagate downstream, the shocks widen and dissipate due to the expulsion of material sideways to the cocoon by the high pressure gradients of the postshock gas. This fading explains the most frequent occurence of knots closer to the driving source. In the case of the long period velocity variability, our simulations have produced a pair of bow-shock-like structures separated by a trail almost Publication: The Astrophysical Journal Pub Date: November 1994 DOI: 10.1086/174811 arXiv: arXiv:astro-ph/9405035 Bibcode: 1994ApJ...435..261D Keywords: Astronomical Models; Interstellar Matter; Magnetohydrodynamic Flow; Plasma Jets; Pre-Main Sequence Stars; Shock Waves; Stellar Mass Ejection; Supersonic Jet Flow; Jet Flow; Mathematical Models; Shock Wave Interaction; Three Dimensional Models; Astrophysics; HYDRODYNAMICS; ISM: INDIVIDUAL ALPHANUMERIC: HH 46/47; ISM: INDIVIDUAL ALPHANUMERIC: HH 111; STARS: PRE--MAIN-SEQUENCE; Astrophysics E-Print: accepted by ApJ, LaTex file, 33 pages full text sources arXiv | ADS | data products SIMBAD (3)