Hubble Space Telescope Images of the HH 111 Jet.

Abstract

view Abstract Citations (105) References (51) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hubble Space Telescope Images of the HH 111 Jet. Reipurth, Bo ; Hartigan, Patrick ; Heathcote, Steve ; Morse, Jon A. ; Bally, John Abstract We have observed the classic Herbig-Haro jet HH 111 with the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope (\HST) through narrow-band filters isolating Hα and [S II]lambda lambda6716 ,6731 emission. The new images fully resolve the body of the jet into a series of small bow shocks, which we conclude form as fast jet material overruns slower, previously ejected jet material. Collisionally excited Hα emission that originates from a series of sharp arcs indicate the locations of shock fronts in the jet. The [S II] emission typically follows Hα in a cooling zone behind the shocks. In some, but not all cases, a Mach disk appears within the bow shocks. Some Balmer arcs form complete bow shocks, while others are one-sided. The jet has a pronounced sinuous structure which we ascribe to variations in the velocity and angle of ejection from the embedded driving source. The faintness of the shocks that propagate outside the jet beam suggests that the surrounding medium has a much lower density than the jet. The major bow shocks along the flow, HH 111L and V, each show a sharp leading edge which is especially bright in Hα . As with other Hα arcs in the flow, we argue that this emission is collisionally excited at the shock fronts. Extended [S II]-bright layers offset from the leading Hα emission in each bow shock appear to indicate the post-shock cooling zones. Bright, low-excitation knots located along the jet axis and nested within the bow shocks may form part of the Mach disk in each working surface. HH 111L is resolved into at least two distinct bow-shaped arcs. Future \HST\ observations may clarify as to whether we are observing two bow shocks merging in this object. The new images enable us to reexamine the molecular outflow in HH 111. Weak shocks along the periphery of the jet appear to accelerate a tube of slow CO gas along the base of the HH 111 jet. High-velocity CO and H_2 emission observed along the axis of the jet likely originates in jet gas that has cooled and become molecular. The three extended jets thus far observed by \HST\ (HH 34, HH 47, and HH 111) share several morphological characteristics which are best explained if variation in both velocity and direction produce most of the observable shocks in the flows. In all cases, the jets move into the wake of previously ejected jet material, and form shocks where they overrun slower jet gas. All three jets show faint Balmer arcs along the periphery of the jet beams, which may indicate a common mechanism by which their associated CO outflows are accelerated. Publication: The Astronomical Journal Pub Date: August 1997 DOI: 10.1086/118509 Bibcode: 1997AJ....114..757R Keywords: STARS: PRE-MAIN SEQUENCE; ISM: JETS AND OUTFLOWS full text sources ADS | data products SIMBAD (30) MAST (1) ESA (1)