Twin Herbig-Haro Jets and Molecular Outflows in L1228

Abstract

view Abstract Citations (56) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Twin Herbig-Haro Jets and Molecular Outflows in L1228 Bally, John ; Devine, David ; Fesen, Robert A. ; Lane, Adair P. Abstract We present new optical, near-infrared, and millimeter wavelength observations of the dark cloud L1228 located in the Cepheus Flare. There are at least two active young stellar objects within a 2' diameter region in the L1228 cloud core that drive two separate Herbig-Haro (HH) outflows, a molecular hydrogen jet, and associated CO outflows. The red nebulous object RNO 129 (HH 198), located 1 north of the L1228 cloud core, is a Herbig-Haro flow from a T Tauri star located near the eastern end of the HH object. The Herbig-Haro object HH 199 is associated with a large molecular outflow (L1228A) centered on a low-luminosity (4 Lsun) young stellar object IRAS 20582+7724, the brightest infrared source in this cloud core. The brightest visual wavelength components, HH 199R1 and R2, lie about 8' to the southwest of the IRAS source, where the redshifted lobe of the CO outflow may be breaking out of the molecular cloud. A chain of faint blueshifted (V ≍-40 to -150 km s-1) HH objects, HH 199B1 through HH 199B6, lies to the northeast of the IRAS source toward the blueshifted lobe of the L1228A CO outflow. The projected distance between HH 199R2 and HH 199B6 is about 20' or nearly 2 pc. Near the center of this outflow, a chain of knots bright in the 2.122 microns wavelength 5(1) line of molecular hydrogen extends for about 1' along a nearly east-west axis on both sides of IRAS 20582+7724. This axis differs from that of the L1228A/HH 199 outflow by about 40°. We consider a model in which the jet from IRAS 20582+7724 varies in its ejection direction. At present, the outflow as traced by the H_{2 }jet appears to be impacting dense C3H_{2 }emitting clumps east and west of the IRAS source. A redshifted CO ridge extends 10' to the west of the IRAS source at the same orientation as the H2 jet, but a more prominent northeast-southwest ridge extends along the HH 199 optical axis from HH 199B6 in the northeast, through the IRAS source, to HH 199R2 in the southwest. A periodic blueshifted (V ≍ -40 to -150 km s-1) chain of Herbig-Haro objects, HH 200, is superimposed on the redshifted lobe of the L1228A outflow. It is associated with the low-velocity blueshifted CO lobe of a second outflow, L1228B. The source of this jet is an embedded T Tauri star located 1'S northwest of IRAS 20582+7724. There is a faint HH object 9' to the northeast of the source of the HH 200 jet, directly opposite the location of the bright bow shock at the end of the blueshifted lobe of the HH 200 jet. This lobe may mark the location of an invisible counterjet HH 200 has a projected length of over 18' corresponding to 1.8 pc (assuming a distance of 300 pc to L1228), and it shows quasi-periodic knot spacing of roughly 1' corresponding to a projected spacing of 0.09 pc. At a flow velocity of 300 km s-1, and an assumed outflow inclination angle of 45°, this spacing may be a result of episodes of enhanced mass loss occurring roughly every 500 years. Publication: The Astrophysical Journal Pub Date: November 1995 DOI: 10.1086/176486 Bibcode: 1995ApJ...454..345B Keywords: INFRARED: ISM: LINES AND BANDS; ISM: INDIVIDUAL ALPHANUMERIC: L1228; ISM: JETS AND OUTFLOWS; STARS: PRE-MAIN-SEQUENCE full text sources ADS | data products SIMBAD (26)