Herbig-Haro flows in B335 ^{*,**,***,****}

Stockholm Observatory, Sweden e-mail: magnusg@astro.su.se

Received: 15 May 2007
Accepted: 7 September 2007

Abstract

Aims.To study the Herbig-Haro flows in the nearby dark globule B335. To find new HH objects and H₂ knots, make a proper motion map of the flow activity and investigate physical properties through shock models.

Methods.We have observed optical (Hα and [SII]) and near-IR (2.12 μm H₂) deep fields and taken optical spectra using the 2.56 m Nordic Optical Telescope, as well as a near-UV deep field (U band) using the 3.58 m NTT. In addition we present new SPITZER / IRAC (3.5–8.0 μm) and MIPS (24 μm) observations. We use previous Hα and 2.12 μm H₂ observations taken 15 and 9 years earlier to make proper motion maps. We then investigate the shock physics by matching our spectra with planar shock models.

Results.We discover five new HH objects (HH 119 D–H) in the eastern and one (HH 119 I) in the western lobe of the outflow. From proper motions we find an optically bright, roughly E–W oriented group with high space velocities (200–280 km s^-1) and a near-IR bright, slower group (15–75 km s^-1) moving to the ESE. We also find a system of at least 15 H₂ knots in the western lobe. This (WNW) counterflow suggests the possibility of a binary outflow source, giving rise to two outflow axes with slightly different orientations. We find that the E–W flow is symmetrical with evidence for two outbursts. We make the first detection of [OI]  6300/63 in HH 119 B and Hβ in HH 119 A and B and find their extinctions to be A_V ≈ 1.4 and 4.4, respectively. HH 119 A is found to expand much faster than expected from linear expansion with distance from the outflow source. Using planar shock models we find shock velocities of ~60 km s^-1 (A) and ~35 km s^-1 (B and C). This agrees with A being of higher excitation than B and C. In our U image we detect three of the HH objects and propose that the emission arise from the [OII] λ3728 line and the blue continuum. New SPITZER / IRAC and MIPS observations show most of the HH objects at 4.5 μm and a E–W elongated hour-glass shaped structure at the outflow source. Even at 24 μm it is not clear whether most of the light is direct or reflected.