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

Sollins, P. K.; Megeath, S. Thomas

doi:10.1086/425044

Cited by 19 publications

(25 citation statements)

References 29 publications

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“…In either case, our millimeter data provide strong evidence that NGC 6334 I(N) is forming a cluster of stars, even though an associated NIR cluster has not been identified and may be still in the process of forming. Finally, we note that the virial masses derived from single-dish molecular line spectra (including N 2 H + by Pirogov et al [2003] and HC 3 N by Sollins & Megeath [2004] ) for both NGC 6334 I and I( N ) are several times higher than the total estimated mass contained in the compact millimeter sources. This fact illustrates the wealth of star-forming material in both regions that has either not assembled into compact protostars or exists in a wider distribution of smaller cores below our sensitivity limit.…”

Section: à3mentioning

confidence: 79%

Millimeter Multiplicity in NGC 6334 I and I(N)

Hunter

Brogan

Megeath

et al. 2006

ApJ

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Using the Submillimeter Array (SMA), we have imaged the 1.3 mm continuum emission at the centers of the massive star-forming regions NGC 6334 I and I( N ). In both regions, the SMA observations resolve the emission into multiple millimeter sources, with most of the sources clustered into areas only 10,000 AU in diameter. Toward NGC 6334 I, we find four compact sources: the two brightest (I-SMA1 and I-SMA2) are associated with previously known ammonia cores; I-SMA3 coincides with the peak of the compact H ii region ( NGC 6334 F), and I-SMA4 is a newly discovered object. While I-SMA3 exhibits a mixture of free-free and dust emission, the rest of the objects are dust cores. Toward NGC 6334 I( N ), seven compact dust cores are found, one of which is associated with a faint centimeter source. With the exception of I-SMA3, none of the millimeter sources have infrared counterparts in Spitzer Space Telescope 3-8 m images. Using a simple physical model for the dust continuum emission, we estimate that the mass of the interstellar material toward each of these compact objects is in the range of 3-66 M . The total mass in the compact objects appears to be similar in I and I( N ). The small size of these groups of sources suggest that these objects are proto-Trapezia forming in the centers of clusters of low-to intermediate-mass stars.

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Section: à3mentioning

confidence: 79%

Millimeter Multiplicity in NGC 6334 I and I(N)

Hunter

Brogan

Megeath

et al. 2006

ApJ

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136

238

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“…It also exhibits strong (sub)mm continuum emission but at lower temperatures (∼30 K). Molecular line surveys of NGC 6334I(N) revealed that most species exhibit fainter emission than that found toward NGC 6334I, although there are some species like HC 3 N which are stronger in NGC 6334I(N) (Megeath & Tieftrunk 1999;McCutcheon et al 2000; Thorwirth et al 2003;Sollins & Megeath 2004). No midinfrared and only weak near-infrared emission has been detected toward NGC 6334I(N) by Tapia et al (1996).…”

Section: Introductionmentioning

confidence: 94%

Hot ammonia in NGC 6334I & I(N)

Beuther

Walsh

Thorwirth

et al. 2007

A&A

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Aims. The massive twin cores NGC 6334I and I(N) are in different evolutionary stages and hence ideal targets to study evolutionary variations within the same larger-scale environment. Here, we study the warm, compact gas components. Methods. We imaged the two regions with the Australia Telescope Compact Array (ATCA) at high angular resolution in the NH 3 (3, 3) to (6, 6) inversion lines. Results. Compact emission is detected toward both regions in all observed inversion lines with energy levels up to 407 K above ground. This is particularly surprising for NGC 6334I(N) since it lacks bright infrared emission and is considered a massive cold core at an early evolutionary stage. High optical depth and multiply-peaked line profiles complicate rotation temperature estimates, and we can only conclude that gas components with temperatures >100 K are present in both regions. Toward NGC 6334I, we confirm previous reports of NH 3 (3, 3) maser emission toward the outflow bow-shocks. Furthermore, we report the first detection of an NH 3 (6, 6) maser toward the central region of NGC 6334I. This maser is centered on the second millimeter (mm) peak and elongated along the outflow axis, indicating that this mm continuum core harbors the driving source of the molecular outflow. Toward the main mm peak in NGC 6334I(N), we detect a double-horn line profile in the NH 3 (6, 6) transition. The current data do not allow us to differentiate whether this double-horn profile is produced by multiple gas components along the line of sight, or whether it may trace a potential underlying massive accretion disk.

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“…Furthermore, weak cm continuum and class i and ii CH 3 OH maser emission was reported (Carral et al 2002;Kogan & Slysh 1998;Caswell 1997;Walsh et al 1998). 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.…”

Section: Introductionmentioning

confidence: 95%

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

Cited by 19 publications

References 29 publications

Millimeter Multiplicity in NGC 6334 I and I(N)

Millimeter Multiplicity in NGC 6334 I and I(N)

Hot ammonia in NGC 6334I & I(N)

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

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