Characterizing filaments in regions of high-mass star formation: High-resolution submilimeter imaging of the massive star-forming complex NGC 6334 with ArTéMiS

Abstract

Context. Herschel observations of nearby molecular clouds suggest that interstellar filaments and prestellar cores represent two fundamental steps in the star formation process. The observations support a picture of low-mass star formation according to which filaments of ∼0.1 pc width form first in the cold interstellar medium, probably as a result of large-scale compression of interstellar matter by supersonic turbulent flows, and then prestellar cores arise from gravitational fragmentation of the densest filaments. Whether this scenario also applies to regions of high-mass star formation is an open question, in part because the resolution of Herschel is insufficient to resolve the inner width of filaments in the nearest regions of massive star formation. Aims. In an effort to characterize the inner width of filaments in high-mass star-forming regions, we imaged the central part of the NGC 6334 complex at a resolution higher by a factor of >3 than Herschel at 350 µm. Methods. We used the large-format bolometer camera ArTéMiS on the APEX telescope and combined the high-resolution ArTéMiS data at 350 µm with Herschel/HOBYS data at 70-500 µm to ensure good sensitivity to a broad range of spatial scales. This allowed us to study the structure of the main narrow filament of the complex with a resolution of 8 or <0.07 pc at d ∼ 1.7 kpc. Results. Our study confirms that this filament is a very dense, massive linear structure with a line mass ranging from ∼500 M /pc to ∼2000 M /pc over nearly 10 pc. It also demonstrates for the first time that its inner width remains as narrow as W ∼ 0.15 ± 0.05 pc all along the filament length, within a factor of <2 of the characteristic 0.1 pc value found with Herschel for lower-mass filaments in the Gould Belt. Conclusions. While it is not completely clear whether the NGC 6334 filament will form massive stars in the future, it is two to three orders of magnitude denser than the majority of filaments observed in Gould Belt clouds, and has a very similar inner width. This points to a common physical mechanism for setting the filament width and suggests that some important structural properties of nearby clouds also hold in high-mass star-forming regions.Key words. stars: formation -circumstellar matter -ISM: clouds -ISM: structure -ISM: individual objects: NGC 6334 -submillimeter: ISM This publication is based on data acquired with the Atacama Pathfinder Experiment (APEX) in ESO program 091.C-0870. APEX is a collaboration between the Max-Planck-Institut für Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory.The final ArTéMiS+SPIRE 350 µm map (Fig. 1b) is available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via

Properties of interstellar filaments as derived from Herschel, Planck, and molecular line observations

“…The observational finding of a filament uniform 0.1 pc width (Arzoumanian et al, 2011) sets strong constraints on the physics at play in the ISM. This result has been recently observed (at higherresolution) from the ground in regions farther away than the Gould Belt (Hill et al, 2012;André et al, 2016).…”

X Marks the Spot: Nexus of Filaments, Cores, and Outflows in a Young Star-forming Region

“…Near the outflow, infrared observations reveal the presence of two bright sources, one of which is a YSO candidate that could be driving the outflow. While a number of studies have considered filaments feeding into clusters (e.g., Myers 2009;Schneider et al 2012;André et al 2016), there has been less of a focus on the role of filamentary structure in the formation of individual stars, as we observe in this interesting structure within the CMC. All in all, Cal-X provides an ideal opportunity for investigating incipient star formation in a relatively pristine environment.…”

The earliest phases of high-mass star formation, as seen in NGC 6334 by Herschel-HOBYS

“…The shape and velocity drift of the south-western part of the ridge (i.e., the connecting filament in Fig. 2, see also Zernickel et al 2013;André et al 2016) recalls sub-filaments falling onto ridges, like those around DR21 (Schneider et al 2010b). Interestingly, the 13 The statistical lifetime of protostellar MDCs has been corrected by Russeil et al (2010) from values given in .…”

“…The 2 × 10 23 cm −2 contours outline the NGC 6334 ridge spanning a 2 pc × 1 pc area and containing the I and I(N) sources as well as two smaller hubs with ∼0.8 pc diameters. A narrow filament discussed at length in Matthews et al (2008) and André et al (2016) connects the ridge and largest hub (see Fig. 2).…”