2000ApJ...538..698M -
Astrophys. J., 538, 698-709 (2000/August-1)
Infrared space observatory spectroscopy of HH 7-11 flow and its redshifted counterpart.
MOLINARI S., NORIEGA-CRESPO A., CECCARELLI C., NISINI B., GIANNINI T., LORENZETTI D., CAUX E., LISEAU R., SARACENO P. and WHITE G.J.
Abstract (from CDS):
We have used the two spectrometers on the Infrared Space Observatory to observe the HH 7-11 flow, its redshifted counterpart, and the candidate exciting source SVS 13 in the star formation region NGC 1333. We detect atomic ([O I] 63 µm, [O I] 145 µm, [Si II] 34.8 µm, [C II] 158 µm) and molecular (H2, CO, H2O) lines at various positions along the bipolar flow. Most of the observed lines can be explained in terms of shock-excited emission. In particular, our analysis shows that dissociative (J-type) and nondissociative (C-type) shocks are simultaneously present everywhere along both lobes of the flow. We confirm the low-excitation nature of the Herbig-Haro nebulosities, with shock velocities vs≲40-50 km.s–1. Toward both lobes of the outflow, we find preshock densities of n0∼104 cm–3 for both the J and C components, implying B0∼100 µG for B0∝n0.50. In the central region of the flow, close to the exciting source, the preshock density deduced for the C-shock component is n0∼105 cm–3, suggesting a magnetic field ∼3 times stronger. We propose that the deficiency of gas-phase water in the post-C-shock regions is caused by freezing onto warm grains processed through the J-shock front and traveling along the magnetic field lines. The total observed cooling from the dissociative shock components is consistent with the power lost by a slow molecular outflow accelerated by a fast neutral HI wind. Finally, the skin of the cloud seen in projection toward the flow appears to be weakly photoionized by BD +30°549, the dominant illuminating source of the NGC 1333 reflection nebula.
Abstract Copyright:
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Journal keyword(s):
ISM: Herbig-Haro Objects - ISM: individual (HH 7-11) - ISM: Lines and Bands - ISM: Molecules - Stars: Formation
Nomenclature:
Table 1, Fig.1: [MNC2000] RL N (Nos 1-2).
Simbad objects:
13
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