Magnetized filamentary gas flows feeding the young embedded cluster in Serpens South

Pillai, T.; Clemens, D. P.; Reißl, Stefan; Myers, Philip C.; Kauffmann, Jens; López-Rodríguez, Enrique; Alves, F. O.; Franco, G. A. P.; Henshaw, Jonathan D.; Menten, K. M.; Nakamura, Fúmitaka; Seifried, D.; Sugitani, Koji; Wiesemeyer, H.

doi:10.1038/s41550-020-1172-6

Cited by 80 publications

(60 citation statements)

References 56 publications

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“…13 and 14). This trend has also been found recently towards the G33.92+0.11 (Wang et al 2020) and Serpens South (Pillai et al 2020) hubfilament systems. This finding suggests that the sub-filaments may be formed orthogonal to the ambient B-field and then merged with the ridge, forming a clump-hub structure, due to, e.g., shock compression events, interstellar turbulence, or under the gravitational attraction by the ridge itself.…”

Section: The B-field Structure Of a High-mass Star Forming Hub-filamesupporting

confidence: 79%

Dust polarized emission observations of NGC 6334

Arzoumanian¹,

Furuya²,

Hasegawa³

et al. 2021

A&A

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Context. Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation. Methods. We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polarized intensity (PI), the polarization fraction (PF), and the plane-of-the-sky B-field angle (χB_POS) toward the whole region, along the 10 pc-long ridge and along the sub-filaments connected to the ridge and the hubs. We derived the power spectra of the intensity and χBPOS along the ridge crest and compared them with the results obtained from simulated filaments. Results. The observations span ~3 orders of magnitude in Stokes I and PI and ~2 orders of magnitude in PF (from ~0.2 to ~ 20%). A large scatter in PI and PF is observed for a given value of I. Our analyses show a complex B-field structure when observed over the whole region (~ 10 pc); however, at smaller scales (~1 pc), χBPOS varies coherently along the crests of the filament network. The observed power spectrum of χBPOS can be well represented with a power law function with a slope of − 1.33 ± 0.23, which is ~20% shallower than that of I. We find that this result is compatible with the properties of simulated filaments and may indicate the physical processes at play in the formation and evolution of star-forming filaments. Along the sub-filaments, χBPOS rotates frombeing mostly perpendicular or randomly oriented with respect to the crests to mostly parallel as the sub-filaments merge with the ridge and hubs. This variation of the B-field structure along the sub-filaments may be tracing local velocity flows of infalling matter in the ridge and hubs. Our analysis also suggests a variation in the energy balance along the crests of these sub-filaments, from magnetically critical or supercritical at their far ends to magnetically subcritical near the ridge and hubs. We also detect an increase in PF toward the high-column density (NH2 ≳ 1023 cm−2) star cluster-forming hubs. These latter large PF values may be explained by the increase in grain alignment efficiency due to stellar radiation from the newborn stars, combined with an ordered B-field structure. Conclusions. These observational results reveal for the first time the characteristics of the small-scale (down to ~ 0.1 pc) B-field structure of a 10 pc-long hub-filament system. Our analyses show variations in the polarization properties along the sub-filaments that may be tracing the evolution of their physical properties during their interaction with the ridge and hubs. We also detect an impact of feedback from young high-mass stars on the local B-field structure and the polarization properties, which could put constraints on possible models for dust grain alignment and provide important hints as to the interplay between the star formation activity and interstellar B-fields.

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Section: The B-field Structure Of a High-mass Star Forming Hub-filamesupporting

confidence: 79%

Dust polarized emission observations of NGC 6334

Arzoumanian¹,

Furuya²,

Hasegawa³

et al. 2021

A&A

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“…If the material were infalling on to the Ridge/Hot Core region, this would be similar to the behaviour seen on much larger size scales in hub-filament systems (e.g. Pillai et al 2020), where magnetic fields are seen to run along filaments of material infalling on to the central hub. The reordered field representing outflowing material is more difficult to physically motivate, as the most likely cause of such a gas outflow would be the BN/KL explosion, with which our observed polarization geometry is not consistent.…”

Section: Discussion Of Grain Alignment In the Anomalous Region/forksupporting

confidence: 55%

OMC-1 dust polarization in ALMA Band 7: diagnosing grain alignment mechanisms in the vicinity of Orion Source I

Pattle

Lai

Wright

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present ALMA Band 7 polarisation observations of the OMC-1 region of the Orion molecular cloud. We find that the polarisation pattern observed in the region is likely to have been significantly altered by the radiation field of the >104 L⊙ high-mass protostar Orion Source I. In the protostar’s optically thick disc, polarisation is likely to arise from dust self-scattering. In material to the south of Source I – previously identified as a region of ‘anomalous’ polarisation emission – we observe a polarisation geometry concentric around Source I. We demonstrate that Source I’s extreme luminosity may be sufficient to make the radiative precession timescale shorter than the Larmor timescale for moderately large grains ($> 0.005\,-\,0.1\, \mu$m), causing them to precess around the radiation anisotropy vector (k-RATs) rather than the magnetic field direction (B-RATs). This requires relatively unobscured emission from Source I, supporting the hypothesis that emission in this region arises from the cavity wall of the Source I outflow. This is one of the first times that evidence for k-RAT alignment has been found outside of a protostellar disc or AGB star envelope. Alternatively, the grains may remain aligned by B-RATs and trace gas infall on to the Main Ridge. Elsewhere, we largely find the magnetic field geometry to be radial around the BN/KL explosion centre, consistent with previous observations. However, in the Main Ridge, the magnetic field geometry appears to remain consistent with the larger-scale magnetic field, perhaps indicative of the ability of the dense Ridge to resist disruption by the BN/KL explosion.

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“…In addition, the relative orientation also depends on the characteristics of the environment and the scale such as those of cores or clumps (Zhang et al 2014;Hull et al 2017;Alina et al 2019). Recently Pillai et al (2020) reported a discovery of a change of the relative orientation from perpendicular to parallel with increasing density in the open cluster in the Serpens south cloud using Sofia HAWC+ data with sub-arcminute resolution. This is a step forward in confirming the paradigm of the relative orientation between matter and magnetic fields in molecular clouds.…”

Section: Discussionmentioning

confidence: 99%

Large-scale magnetic field in the Monoceros OB 1 east molecular cloud

Alina

Montillaud

et al. 2022

A&A

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Context. The role of large-scale magnetic fields in the evolution of star-forming regions remains elusive. Its investigation requires the observational characterization of well-constrained molecular clouds. The Monoceros OB 1 molecular cloud is a large complex containing several structures that have been shown to be engaged in an active interaction and to have a rich star formation history. However, the magnetic fields in this region have only been studied on small scales. Aims. We study the large-scale magnetic field structure and its interplay with the gas dynamics in the Monoceros OB 1 east molecular cloud. Methods. We combined observations of dust polarized emission from the Planck telescope and CO molecular line emission observations from the Taeduk Radio Astronomy Observatory 14-metre telescope. We calculated the strength of the plane-of-sky magnetic field using a modified Chandrasekhar-Fermi method and estimated the mass-over-flux ratios in different regions of the cloud. We used the comparison of the velocity and intensity gradients of the molecular line observations with the polarimetric observations to trace dynamically active regions. Results. The molecular complex shows an ordered large-scale plane-of-sky magnetic field structure. In the northern part, it is mostly orientated along the filamentary structures, while the southern part shows at least two regions with distinct magnetic field orientations. Our analysis reveals a shock region in the northern part right between two filamentary clouds that, in previous studies, were suggested to be involved in a collision. The magnetic properties of the north-main and north-eastern filaments suggest that these filaments once formed a single one, and that the magnetic field evolved together with the material and did not undergo major changes during the evolution of the cloud. In the southern part, we find that either the magnetic field guides the accretion of interstellar matter towards the cloud or it is dragged by the matter falling towards the main cloud. Conclusions. The large-scale magnetic field in the Monoceros OB 1 east molecular cloud is tightly connected to the global structure of the complex. In the northern part, it seems to serve a dynamically important role by possibly providing support against gravity in the direction perpendicular to the field and to the filament. In the southern part, it is probably the most influential factor governing the morphological structure by guiding possible gas inflow. A study of the whole Monoceros OB 1 molecular complex at large scales is necessary to form a global picture of the formation and evolution of the Monoceros OB 1 east cloud and the role of the magnetic field in this process.

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Magnetized filamentary gas flows feeding the young embedded cluster in Serpens South

Cited by 80 publications

References 56 publications

Dust polarized emission observations of NGC 6334

Dust polarized emission observations of NGC 6334

OMC-1 dust polarization in ALMA Band 7: diagnosing grain alignment mechanisms in the vicinity of Orion Source I

Large-scale magnetic field in the Monoceros OB 1 east molecular cloud

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