HH 666: Different kinematics from Hα and [Fe II] emission provide a missing link between jets and outflows

Abstract

HH 666 is an externally irradiated protostellar outflow in the Carina Nebula for which we present new near-IR [Fe II] spectra obtained with the FIRE spectrograph at Magellan Observatory. Earlier Hα and near-IR [Fe II] imaging revealed that the two emission lines trace substantially different morphologies in the inner ~40" of the outflow. Hα traces a broad cocoon that surrounds the collimated [Fe II] jet that extends throughout the parent dust pillar. New spectra show that this discrepancy extends to their kinematics. Near-IR [Fe II] emission traces steady, fast velocities of +/- 200 km/s from the eastern and western limbs of the jet. We compare this to a previously published Hα spectrum that reveals a Hubble-flow velocity structure near the jet-driving source. New, second-epoch HST/ACS Hα images reveal the lateral spreading of the Hα outflow lobe away from the jet axis. Hα proper motions also indicate a sudden increase in the mass-loss rate ~1000 yr ago, while steady [Fe II] emission throughout the inner jet suggests that the burst is ongoing. An accretion burst sustained for ~1000 yr is an order of magnitude longer than expected for FU Orionis outbursts, but represents only a small fraction of the total age of the HH 666 outflow. Altogether, available data suggests that [Fe II] traces the highly collimated protostellar jet while Hα traces the entrained and irradiated outflow. HH 666 appears to be a missing link between bare jets seen in H II regions and entrained molecular outflows seen from embedded protostars in more quiescent regions.

accepted for publication in MNRAS

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Cited by in corpus (10)

• Ancient eruptions of Eta Carinae: A tale written in proper motions
• Proper motions of collimated jets from intermediate-mass protostars in the Carina Nebula
• [Fe II] jets from intermediate-mass protostars in Carina
• A moderately precise dynamical age for the Homunculus of Eta Carinae based on 13 years of HST imaging
• Illuminating the Tadpole's metamorphosis I: MUSE observations of a small globule in a sea of ionizing photons
• Carina's Pillars of Destruction: the view from ALMA
• High-resolution images of two wiggling stellar jets, MHO 1502 and MHO 2147, obtained with GSAOI+GeMS
• Illuminating a tadpole's metamorphosis II: observing the on-going transformation with ALMA
• The Dusty Silhouette Jet HH 1019 in the Carina Nebula
• Extended Ionized Fe Objects in the UWIFE Survey