First Sub-parsec-scale Mapping of Magnetic Fields in the Vicinity of a Very-low-luminosity Object, L1521F-IRS

Soam, Archana; Lee, Chang-Won; Andersson, B. G.; Maheswar, G.; Juvela, M.; Kim, Gwanjeong; Rao, Ramprasad; Chung, Eun Jung; Kwon, Woojin; Ekta, S.

doi:10.3847/1538-4357/ab365d

Cited by 27 publications

(23 citation statements)

References 71 publications

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“…As can be seen in Table 2, M A < 1 in Hub-N, indicating sub-Alfvénic conditions and therefore that magnetic energy dominates over turbulence. Similar results have been found in other IRDCs (e.g., Pillai et al 2015;Soam et al 2019). On the contrary, M A > 1 in Hub-S (i.e., super-Alfvénic conditions), and therefore turbulence could play a more important role in this region.…”

Section: Mass-to-flux Ratio and Turbulencesupporting

confidence: 90%

Role of the magnetic field in the fragmentation process: the case of G14.225-0.506

Añez-López

Busquet

Koch

et al. 2020

A&A

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Context. Magnetic fields are predicted to play a significant role in the formation of filamentary structures and their fragmentation to form stars and star clusters. Aims. We aim to investigate the role of the magnetic field in the process of core fragmentation toward the two hub–filament systems in the infrared dark cloud G14.225-0.506, which present different levels of fragmentation. Methods. We performed observations of the thermal dust polarization at 350 μm using the Caltech Submillimeter Observatory (CSO) with an angular resolution of 10″ toward the two hubs (Hub-N and Hub-S) in the infrared dark cloud G14.225-0.506. We additionally applied the polarization–intensity-gradient method to estimate the significance of the magnetic field over the gravitational force. Results. The sky-projected magnetic field in Hub-N shows a rather uniform structure along the east–west orientation, which is roughly perpendicular to the major axis of the hub–filament system. The intensity gradient in Hub-N displays a single local minimum coinciding with the dust core MM1a detected with interferometric observations. Such a prevailing magnetic field orientation is slightly perturbed when approaching the dust core. Unlike the northern Hub, Hub-S shows two local minima, reflecting the bimodal distribution of the magnetic field. In Hub-N, both east and west of the hub–filament system, the intensity gradient and the magnetic field are parallel whereas they tend to be perpendicular when penetrating the dense filaments and hub. Analysis of the |δ|- and ΣB-maps indicates that, in general, the magnetic field cannot prevent gravitational collapse, both east and west, suggesting that the magnetic field is initially dragged by the infalling motion and aligned with it, or is channeling material toward the central ridge from both sides. Values of ΣB ≳ 1 are found toward a north–south ridge encompassing the dust emission peak, indicating that in this region magnetic field dominates over gravity force, or that with the current angular resolution we cannot resolve a hypothetically more complex structure. We estimated the magnetic field strength, the mass-to-flux ratio, and the Alfvén Mach number, and found differences between the two hubs. Conclusions. The different levels of fragmentation observed in these two hubs could arise from differences in the properties of the magnetic field rather than from differences in the intensity of the gravitational field because the density in the two hubs is similar. However, environmental effects could also play a role.

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Section: Mass-to-flux Ratio and Turbulencesupporting

confidence: 90%

Role of the magnetic field in the fragmentation process: the case of G14.225-0.506

Añez-López

Busquet

Koch

et al. 2020

A&A

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“…In addition, we searched the JCMT data archive for the POL-2 data of other nearby molecular clouds and Bok globules, and we retrieved the data taken with the regular projects M17AP067 (PI: P. Koch), M17AP073 (PI: W. Kwon), M17BP058 (PI: W. Kwon), and M17BP070 (PI: A. Soam). Some of these data have been published by Soam et al (2019) and Yen et al (2019). Then, from these star-forming regions, we selected low-mass Class 0 and I protostars whose molecular outflows have been imaged with interferometric observations at spatial resolutions of a few hundred astronomical units and show more or less well defined axes or cavity walls, so that the directions of their outflows could be accurately determined.…”

Section: Samplementioning

confidence: 99%

The JCMT BISTRO Survey: Alignment between Outflows and Magnetic Fields in Dense Cores/Clumps

Yen

Koch

Hull

et al. 2021

ApJ

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We compare the directions of molecular outflows of 62 low-mass Class 0 and I protostars in nearby (<450 pc) starforming regions with the mean orientations of the magnetic fields on 0.05-0.5 pc scales in the dense cores/clumps where they are embedded. The magnetic field orientations were measured using the JCMT POL-2 data taken by the BISTRO-1 survey and from the archive. The outflow directions were observed with interferometers in the literature. The observed distribution of the angles between the outflows and the magnetic fields peaks between 15°a nd 35°. After considering projection effects, our results could suggest that the outflows tend to be misaligned with the magnetic fields by 50°±15°in three-dimensional space and are less likely (but not ruled out) randomly

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“…SF processes are affected by the combined effects of turbulence, magnetism, thermal pressure, and gravity. There is evidence that the relative importance of these forces changes in structures from filaments to cores (Mattern et al 2018;Liu et al 2018b;Tang et al 2019;Soam et al 2019;Traficante et al 2020). In addition, there is evidence that larger mass reservoirs are required for SF in energetic environments such as the Galactic center (Trujillo-Gomez et al 2019).…”

Section: Introductionmentioning

confidence: 99%

“…The magnetic field dominates in the difuse ISM (Heiles & Troland 2005;Basu & Roy 2013), while the effect of gravity and external pressure is significant on smaller scales (McKee & Ostriker 2007;Maruta et al 2010;Pattle et al 2015). Magnetic energy can be crucial to the formation of filaments, with filaments being either contained by magnetic flux or contracting along magnetic field lines (Crutcher 2012;Juvela et al 2018a;Gholipour 2019;Tang et al 2019;Soam et al 2019). Fragmentation at core scales is likely rapid enough that it does not depend on the larger environment (Kainulainen et al 2013;Hacar et al 2013;Teixeira et al 2016;Mattern et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Characterization of dense Planck clumps observed with Herschel and SCUBA-2

Mannfors

Juvela

Bronfman

et al. 2021

A&A

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Context. Although the basic processes of star formation (SF) are known, more research is needed on SF across multiple scales and environments. The Planck all-sky survey provided a large catalog of Galactic cold clouds and clumps that have been the target of several follow-up surveys. Aims. We aim to characterize a diverse selection of dense, potentially star-forming cores, clumps, and clouds within the Milky Way in terms of their dust emission and SF activity. Methods. We studied 53 fields that have been observed in the JCMT SCUBA-2 continuum survey SCOPE and have been mapped with Herschel. We estimated dust properties by fitting Herschel observations with modified blackbody functions, studied the relationship between dust temperature and dust opacity spectral index β, and estimated column densities. We extracted clumps from the SCUBA-2 850 µm maps with the FellWalker algorithm and examined their masses and sizes. Clumps are associated with young stellar objects found in several catalogs. We estimated the gravitational stability of the clumps with virial analysis. The clumps are categorized as unbound starless, prestellar, or protostellar. Results. We find 529 dense clumps, typically with high column densities from (0.3-4.8)×10 22 cm −2 , with a mean of (1.5±0.04)×10 22 cm −2 , low temperatures (T ∼10 -20 K), and estimated submillimeter β=1.7±0.1. We detect a slight increase in opacity spectral index toward millimeter wavelengths. Masses of the sources range from 0.04 M to 4259 M . Mass, linear size, and temperature are correlated with distance. Furthermore, the estimated gravitational stability is dependent on distance, and more distant clumps appear more virially bound. Finally, we present a catalog of properties of the clumps. Conclusions. Our sources present a large array of SF regions, from high-latitude, nearby diffuse clouds to large SF complexes near the Galactic center. Analysis of these regions will continue with the addition of molecular line data, which will allow us to study the densest regions of the clumps in more detail.

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First Sub-parsec-scale Mapping of Magnetic Fields in the Vicinity of a Very-low-luminosity Object, L1521F-IRS

Cited by 27 publications

References 71 publications

Role of the magnetic field in the fragmentation process: the case of G14.225-0.506

Role of the magnetic field in the fragmentation process: the case of G14.225-0.506

The JCMT BISTRO Survey: Alignment between Outflows and Magnetic Fields in Dense Cores/Clumps

Characterization of dense Planck clumps observed with Herschel and SCUBA-2

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