The Detection of Outflows in the Infrared-quiet Molecular Core NGC 6334/I(North)

Megeath, S. Thomas; Tieftrunk, A. R.

doi:10.1086/312374

Cited by 24 publications

(43 citation statements)

References 22 publications

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“…This survey supports the claim of Megeath & Tieftrunk (1999) that NGC 6334 I(N) may be a rare example of a core at the onset of cluster formation. Although there is clear evidence for star formation, there is no IRAS point source, UC H ii region, or young stellar cluster toward this core.…”

Section: Discussionsupporting

confidence: 88%

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A Near-Infrared/Millimeter-Wave Study of Six Fourth-Quadrant High-Mass Star Formation Regions

Sollins

Megeath

2004

Astron J

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We present near-infrared and millimeter-wave observations of six high-mass star-forming regions in the fourth quadrant: RCW 108, G333.6, RCW 117, RCW 122, NGC 6334 I, and G351.6. These regions have heliocentric distances of 1.3-3.0 kpc and total luminosities ranging from 0.5 to 3 ; 10 5 L . Millimeter maps taken in transitions of C 18 O, HC 3 N, 12 C 16 O, and SiO with the Swedish-ESO Submillimetre Telescope 15 m telescope detail the structure and kinematics of the clouds. Near-infrared K-band images of the same regions obtained with the MPG/ESO 2.2 m telescope are used to map the stellar surface density. The C 18 O (1 ! 0) line shows extended high column density gas, with column densities ranging from 10 22 to 3 ; 10 23 cm À2 ; in contrast, the HC 3 N (15 ! 14) emission shows eight sharply peaked dense cores. We examine these cores for recent and ongoing star formation by searching for high-velocity, non-Gaussian wings on the CO (1 ! 0) and SiO (2 ! 1) lines, peaks in the surface density of stars, and positional coincidences with IRAS point sources, as well as masers and H ii regions reported in the literature. All of the cores show evidence of ongoing star formation. NGC 6334 I(N) stands out as a unique case in which an outflow has formed and masers have appeared, but no IRAS source, K-band cluster, or UC H ii region has yet appeared; our data support previous claims that this is a rare example of a core in the earliest stages of forming a cluster of high-and low-mass stars.

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Section: Discussionsupporting

confidence: 88%

“…In the tentative detections, the residuals were roughly 3 . The wings in NGC 6334 I and I(N) are associated with known bipolar outflows in this source (Megeath & Tieftrunk 1999). …”

Section: The Detection Of Line Wing Gsmentioning

confidence: 73%

A Near-Infrared/Millimeter-Wave Study of Six Fourth-Quadrant High-Mass Star Formation Regions

Sollins

Megeath

2004

Astron J

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“…The 2nd southeast northwest outflow is so far only observed at lower spatial resolution by Megeath & Tieftrunk (1999), who did not identify a driving source for it. While it could emanate from any other source, e.g., mm2, it is also possible that it originates from the vicinity of mm1.…”

Section: A Precessing Outflow?mentioning

confidence: 95%

“…The spectral line forest is considerably less dense compared to NGC 6334I (Thorwirth et al 2003), however, a few species are stronger toward NGC 6334I(N) (Sollins & Megeath 2004;Walsh et al in prep.). In addition, Megeath & Tieftrunk (1999) reported the detection of a molecular outflow in this region as well. In summary, both regions show signs of active star formation, however, the southern region NGC 6334I appears to be in a more advanced evolutionary stage than the northern region NGC 6334I(N).…”

Section: Introductionmentioning

confidence: 91%

ATCA 3 mm observations of NGC 6334I and I(N): dense cores, outflows, and an UCH II region

Beuther¹,

Walsh²,

Thorwirth

et al. 2008

A&A

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Aims. We investigate the dense gas, the outflows, and the continuum emission from the massive twin cores NGC 6334I and I(N) at high spatial resolution. Methods. We imaged the region with the Australia Telescope Compact Array (ATCA) at 3.4 mm wavelength in continuum, as well as CH 3 CN(5 K −4 K ) and HCN(1−0) spectral line emission. Results. While the continuum emission in NGC 6334I mainly traces the UCHii region, toward NGC 6334I(N) we detect continuum emission from four of the previously identified dust continuum condensations that are of protostellar or pre-stellar nature. The CH 3 CN(5 K −4 K ) lines are detected in all K-components up to energies of 128 K aboveground toward two protostellar condensations in both regions. We find line width increasing with increasing K for all sources, which indicates a higher degree of internal motions of the hotter gas probed by these high K-transitions. Toward the main mm and CH 3 CN source in NGC 6334I, we identify a velocity gradient approximately perpendicular to the large-scale molecular outflow. This may be interpreted as a signature of an accretion disk, although other scenarios, e.g., an unresolved double source, could produce a similar signature. No comparable signature is found toward any of the other sources. HCN does not trace the dense gas well in this region but it is dominated by the molecular outflows. While the outflow in NGC 6334I exhibits a normal Hubble-law like velocity structure, the data are consistent with a precessing outflow close to the plane of the sky for NGC 6334I(N). Furthermore, we observe a wide (∼15.4 km s −1 ) HCN absorption line, much broader than the previously observed CH 3 OH and NH 3 absorption lines. Several explanations for the difference are discussed. The fits-files of the 3.4 mm continuum images and of the HCN(1−0) and CH 3 CN(5 K −4 K ) data-cubes are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via

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“…If an outflow was detected with CO J = 3−2 or higher transition lines, it is noted in the table accordingly. Some authors detected molecular outflows with other molecular species, such as SiO, CS, HCO + (e.g., Megeath & Tieftrunk 1999;Wolf-Chase et al 1998;Garay et al 1998;Hofner et al 2001). These species are not included in this catalogue.…”

Section: The Samplementioning

confidence: 99%

A study of high velocity molecular outflows with an up-to-date sample

Wu¹,

Wei²,

Zhao³

et al. 2004

A&A

294

291

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Abstract.A statistical study of the properties of molecular outflows is performed based on an up-to-date sample. 391 outflows were identified in published articles or preprints before February 28, 2003. The parameters of position, morphology, mass, energy, outflow dynamics and central source luminosity are presented for each outflow source. Outflow lobe polarity is known for all the sources, and 84% are found to be bipolar. The sources are divided into low mass and high mass groups according to either the available bolometric luminosity of the central source or the outflow mass. The pace of discovery of outflows over the past seven years has increased much more rapidly than in previous periods. Surveys for outflows are still continuing. The number of high-mass outflows detected (139) has considerably increased, showing that they are commonly associated with massive as well as low mass stars. Energetic mass ejection may be a common aspect of the formation of high mass as well as low mass stars. Outflow masses are correlated strongly with bolometric luminosity of the center sources, which was obtained for the first time. There are also correlations between the central source luminosity and the parameters of mechanical luminosity and the thrust or force necessary to drive the outflow. The results show that flow mass, momentum and energy depend on the nature of the central source. Despite their similarity, there are differences between the high mass and low mass outflows. Low mass outflows are more collimated than high mass outflows. On average, the mass of high mass sources can be more than two orders of magnitude larger than those of low mass outflows. The relation between flow mass and dynamical time appears to differ for the two types of outflows. Low mass sources make up 90% of outflows associated with HH objects while high mass outflows make up 61% of the sources associated with H 2 O masers. Sources with characteristics of collapse or infall comprise 12% of the entire outflow sample. The spatial distribution of the outflow sources in the Galaxy is presented and the local occurrence rate is compared with the stellar birth rate.

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The Detection of Outflows in the Infrared-quiet Molecular Core NGC 6334/I(North)

Cited by 24 publications

References 22 publications

A Near-Infrared/Millimeter-Wave Study of Six Fourth-Quadrant High-Mass Star Formation Regions

A Near-Infrared/Millimeter-Wave Study of Six Fourth-Quadrant High-Mass Star Formation Regions

ATCA 3 mm observations of NGC 6334I and I(N): dense cores, outflows, and an UCH II region

A study of high velocity molecular outflows with an up-to-date sample

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