Parsec-scale CO outflow and H-2 jets in Barnard 5

New observations of the Barnard 5 IRS 1 molecular outflow, including maps i n the (CO)-C-12 J = 2-1 transition and images and high-resolution spectra i n the H-2 v = 1-0 S(1) line, are presented. In the (CO)-C-12 J = 2-1 maps, the outflow has a projected length of over 30' (3 pc) and is highly collima ted with a width smaller than 2' (0.2 pc), with one outflow lobe containing clear evidence of a limb-brightened cavity. Like the associated Herbig-Har o how, the CO lobes exhibit C-shaped symmetry about IRS 1. Bow- or cone-sha ped clumps, which are not associated with visible shocks, are located at th e ends of the CO outflow. While the presence of Herbig-Haro objects and ass ociated shock excited H-2 emission in the outer parts of the CO how several arcminutes closer to the source indicate that a relatively recent mass-los s episode is still transferring momentum to CO-bearing gas, these terminal CO structures may provide a fossil record of a much older mass-loss episode . The new observations provide support for bow shock entrainment models for the acceleration of CO-bearing gas. Several 15' long (CO)-C-12-emitting fi laments lie parallel to but displaced by several arcminutes from the IRS 1 outflow. These features may trace perturbations excited by magnetosonic wav es triggered by major mass-loss eruption episodes of IRS 1. The terminal H- 2 emission closely traces the H alpha and [S II] emission produced by Herbi g-Haro objects located near the ends of the main CO outflow body and is lik ely to be powered by shocks. However, the H-2 emission is systematically di splaced downstream from the Herbig-Haro objects. Since the B5 outflow appea rs to lie within 13 degrees of the plane of the sky, this displacement is n ot likely to be a geometric projection effect. The specific excitation mech anism may require heating by a magnetic precursor or fluorescence produced by radiation originating in the shocks associated with the Herbig-Haro obje cts. A compact chain of H-2 knots located within 30 " of IRS 1 appears to d elineate a bipolar jet originating from this source. This H-2 feature and t he associated Ha emission bisects the limb-brightened CO cones found within 20 " of IRS 1. The presence of both axial knots and a wide-angle cavity im plies that the central source may simultaneously power both a jet and a wid e-angle wind that are formed within 2000 AU of IRS I. A new method that acc ounts for the velocity dependence of the (CO)-C-12 optical depth is used to estimate the mass in the outflow lobes. The resulting power-law mass spect ra have slopes that are much steeper than those obtained by assuming that t he (CO)-C-12 line is optically thin in the outflow lobes, an assumption tha t has been frequently used in other studies. The flow orientation, the outf low evolution, and the velocity at which the outflow lobes becomes opticall y thin also affect the mass spectrum. The source luminosity, outflow dynami c timescale, outflow strength, and embedded nature of IRS 1 imply that it i s in an intermediate evolutionary stage between a Class I and Class 0 sourc e. We also present a new optical spectrum of HH 367, which originates from IRS 3, confirming its Herbig-Haro nature and showing evidence for different excitation conditions along the flow and variable mass ejection rates from the source.