The IRAS 2 and IRAS 4 Outflows and Star Formation in NGC 1333

Langer, W. D.; Castets, A.; Leflóch, B.

doi:10.1086/310337

Cited by 29 publications

(41 citation statements)

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“…A strong CO outflow in the north-south direction has also been observed (Liseau et al 1988;Engargiola & Plambeck 1999), which originates within a few arcseconds from IRAS 2A (Jørgensen et al 2004a). Langer et al (1996) mapped the entire NGC 1333 region in CS and identified two peaks in CS emission toward the IRAS 2 outflow. They suggested that these are associated with red-shifted (eastern) and blue-shifted (western) bow shock components of the outflow.…”

Section: Introductionmentioning

confidence: 66%

The impact of shocks on the chemistry of molecular clouds

Jørgensen

Hogerheijde

Blake

et al. 2004

A&A

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Abstract. This paper presents a detailed study of the chemistry in the outflow associated with the low-mass protostar NGC 1333-IRAS 2A down to 3 (650 AU) scales. Millimeter-wavelength aperture-synthesis observations from the Owens Valley and Berkeley-Illinois-Maryland-Association interferometers and (sub)millimeter single-dish observations from the Onsala Space Observatory 20 m telescope and Caltech Submillimeter Observatory are presented. The interaction of the highly collimated protostellar outflow with a molecular condensation ∼15 000 AU from the central protostar is clearly traced by molecular species such as HCN, SiO, SO, CS, and CH 3 OH. Especially SiO traces a narrow high velocity component at the interface between the outflow and the molecular condensation. Multi-transition single-dish observations are used to distinguish the chemistry of the shock from that of the molecular condensation and to address the physical conditions therein. Statistical equilibrium calculations reveal temperatures of 20 and 70 K for the quiescent and shocked components, respectively, and densities near 10 6 cm −3 . The line-profiles of low-and high-excitation lines are remarkably similar, indicating that the physical properties are quite homogeneous within each component. Significant abundance enhancements of two to four orders of magnitude are found in the shocked region for molecules such as CH 3 OH, SiO and the sulfur-bearing molecules. HCO + is seen only in the aftermath of the shock consistent with models where it is destroyed through release of H 2 O from grain mantles in the shock. N 2 H + shows narrow lines, not affected by the outflow but rather probing the ambient cloud. The overall molecular inventory is compared to other outflow regions and protostellar environments. Differences in abundances of HCN, H 2 CO and CS are seen between different outflow regions and are suggested to be related to differences in the atomic carbon abundance. Compared to the warm inner parts of protostellar envelopes, higher abundances of in particular CH 3 OH and SiO are found in the outflows, which may be related to density differences between the regions.

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Section: Introductionmentioning

confidence: 66%

The impact of shocks on the chemistry of molecular clouds

Jørgensen

Hogerheijde

Blake

et al. 2004

A&A

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“…Langer et al (1996) also observed components of emission in CS at similar velocities, and suggested that the ∼8 km s −1 layer is a dense compressed shell surrounding a cavity created by A150, page 6 of 12 the outflows. For the C1 component, we find that H 13 CO + has a 4 → 3/1 → 0 ratio 5 times greater than that for HN 13 C. This is in contrast to component C2, where the upper limit of the HN 13 C 4 → 3/1 → 0 ratio is similar to that of H 13 CO + .…”

Section: Ngc 1333mentioning

confidence: 81%

“…dynamical processes. For example Langer et al (1996) suggested that the 8 km s −1 structure observed towards NGC 1333 is a dense shell of gas, compressed by the outflows in the region.…”

Section: Resultsmentioning

confidence: 99%

The search for the magnetic precursor of C-type shocks in young molecular outflows

Roberts¹,

Jiménez-Serra²,

Martı́n-Pintado³

2012

A&A

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The detection of very narrow SiO emission and the higher degree of excitation of the ion fluid compared to the neutral one towards the protostar L1448-mm have been interpreted as signatures of the magnetic precursor of C-shocks. Since this is the only source where these features have been observed together, we carried out a survey to map the J = 2 → 1 and 8 → 7 lines of SiO, and the J = 1 → 0 and 4 → 3 lines of H 13 CO + (as the representative ion) and HN 13 C (as the representative neutral species) towards four class 0/I low-mass protostars known to have young outflows (L1448-IRS3, NGC 1333-IRAS 4A/B and SSV 13, VLA 1623 and IRAS 20353). As previously reported, towards L1448-IRS3 and NGC 1333 strong, narrow SiO 2 → 1 is detected, and we also find a velocity component towards each outflow which shows high a H 13 CO + 4 → 3/1 → 0 integrated intensity ratio compared to that of HN 13 C. Towards VLA 1623, we find very weak, narrow SiO, and a component that is visible in H 13 CO + but not at all in HN 13 C. For IRAS 20353, we find neither narrow SiO nor high H 13 CO + 4 → 3/1 → 0 flux ratios. Previous work explained the higher degree of excitation of H 13 CO + by the selective excitation of ions by electrons, whose abundance is expected to increase at the precursor stage. Here, however, by considering a range of kinetic temperatures for the gas, we find that it is possible to fit the observations with a single temperature and density, without an increased electron abundance, despite the large differences in 4 → 3/1 → 0 ratio between the two molecules. The high H 13 CO + 4 → 3/1 → 0 flux ratios may simply be due to protostellar heating. However, the hypothesis that narrow SiO is formed at the precursor stage of shocks remains plausible, since other explanations require either the presence of shocks with larger dynamical timescales, or predict the narrow SiO to have a larger spatial extent than it appears to have towards the sources L1448-IRS3 and VLA 1623. Larger scale maps of the narrow SiO emission are needed to confirm that it is confined to the regions around protostars (as would be expected in the precursor scenario), and mapping of different ion and neutral species is necessary to confirm whether there are indeed precursor regions surrounding young outflows where the ion and neutral species behave as separate fluids.

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“…A large scale outflow, oriented along the north-south axis of the source, has been detected in CO 3-2 and 2-1 emission (Knee & Sandell 2000). A second outflow, oriented east and west, is detected in SiO 2-1 (Blake 1996;Jørgensen et al 2004a) and CS 3-2 (Langer et al 1996). Strong CH 3 OH lines have also been observed at the endpoint of this outflow (∼70 east and west of the central position), where the methanol abundance is enhanced by a factor of 300 (Bachiller et al 1998).…”

Section: Resultsmentioning

confidence: 98%

CH$_\mathsf{3}$OH abundance in low mass protostars

Maret¹,

Ceccarelli²,

Tielens

et al. 2005

A&A

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We present observations of methanol lines in a sample of Class 0 low mass protostars. Using a 1-D radiative transfer model, we derive the abundances in the envelopes. In two sources of the sample, the observations can only be reproduced by the model if the methanol abundance is enhanced by about two order of magnitude in the inner hot region of the envelope. Two other sources show similar jumps, although at a lower confidence level. The observations for the other three sources are well reproduced with a constant abundance, but the presence of a jump cannot be ruled out. The observed methanol abundances in the warm gas around low mass protostars are orders of magnitude higher than gas phase chemistry models predict. Hence, in agreement with other evidence, this suggests that the high methanol abundance reflects recent evaporation of ices due to the heating by the newly formed star. The observed abundance ratios of CH 3 OH, H 2 CO and CO are in good agreement with grain surface chemistry models. However, the absolute abundances are more difficult to reproduce and may indicate the presence of multiple ice components in these regions.

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The IRAS 2 and IRAS 4 Outflows and Star Formation in NGC 1333

Cited by 29 publications

References 5 publications

The impact of shocks on the chemistry of molecular clouds

The impact of shocks on the chemistry of molecular clouds

The search for the magnetic precursor of C-type shocks in young molecular outflows

CH$_\mathsf{3}$OH abundance in low mass protostars

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