Kinematic structure of massive star-forming regions

Abstract

Context. The mid-and far-infrared view on high-mass star formation, in particular with the results from the Herschel space observatory, has shed light on many aspects of massive star formation. However, these continuum studies lack kinematic information. Aims. We study the kinematics of the molecular gas in high-mass star-forming regions. Methods. We complemented the PACS and SPIRE far-infrared data of 16 high-mass star-forming regions from the Herschel key project EPoS with N 2 H + molecular line data from the MOPRA and Nobeyama 45 m telescope. Using the full N 2 H + hyperfine structure, we produced column density, velocity, and linewidth maps. These were correlated with PACS 70 μm images and PACS point sources. In addition, we searched for velocity gradients. Results. For several regions, the data suggest that the linewidth on the scale of clumps is dominated by outflows or unresolved velocity gradients. IRDC 18454 and G11.11 show two velocity components along several lines of sight. We find that all regions with a diameter larger than 1 pc show either velocity gradients or fragment into independent structures with distinct velocities. The velocity profiles of three regions with a smooth gradient are consistent with gas flows along the filament, suggesting accretion flows onto the densest regions. Conclusions. We show that the kinematics of several regions have a significant and complex velocity structure. For three filaments, we suggest that gas flows toward the more massive clumps are present.

Understanding star formation in molecular clouds

“…3. This correlation, and the fact that this peak has the same velocity as seen in N 2 H + 1→0 (Tackenberg et al 2014), provides evidence that this high column density clump is clearly an intrinsic part of the IRDC.…”

“…the strongest submm-continuum sources from ATLASGAL (Contreras et al 2013;Csengeri et al 2014) and two positions off-source but within the cloud. The continuum sources were also observed in the optically thin N 2 H + 1→0 line at 93.173 GHz with a velocity resolution of 0.2 km s −1 (Tackenberg et al 2014), and the centre velocities reported in their Table 3 are indicated as a dashed blue line in Fig. 8.…”

“…Fig. 9, and the numbering from 1 to 6 indicates the position of submm-continuum sources seen with ATLASGAL and subsequently observed in N 2 H + (Tackenberg et al 2014). The 12 CO 3→2 (black) and 13 CO 1→0 (red) spectra at these positions are displayed in the panels around.…”

“…8. The dust column density from Herschel is overlaid as blue contours (levels 4, 5, 7, 10, 16 × 10 22 cm −2 ), and the numbering from 1 to 6 indicates the position of submm-continuum sources labelled using ATLASGAL and subsequently observed in N 2 H + (Tackenberg et al 2014). …”

The ATLASGAL survey: The sample of young massive cluster progenitors

“…Case studies of massive cluster progenitors show evidence both for global collapse and for flows of dense gas (e.g. Schneider et al 2010;Csengeri et al 2011a,b;Peretto et al 2013;Tackenberg et al 2014). This points to a scenario where massive clumps undergo star formation, while gas replenishment arrives on larger scales, and maintains the observed similar mass range for these clumps.…”