A Corona Australis cloud filament seen in NIR scattered light

Juvela, M.; Pelkonen, Veli-Matti; White, G. J.; Könyves, V.; Kirk, J. M.; André, P.

doi:10.1051/0004-6361/201219084

Cited by 13 publications

(22 citation statements)

References 94 publications

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“…5 suggest that the radiation field in TMC-1N is notably lower in all three NIR bands when compared to similar observations of Corona Australis (Juvela et al 2008). This reaffirms the results obtained with dust emission models of Juvela et al (2012), suggesting that the radiation field in Corona Australis is at least three times that of the normal ISRF.…”

Section: Discussionsupporting

confidence: 89%

“…Juvela et al (2008) used scattered NIR light to derive a column density map of a part of a filament in Corona Australis, and continued the analysis in a larger area in Juvela et al (2009). They also compared the NIR data with Herschel sub-millimetre data in Juvela et al (2012). Nakajima et al (2008) applied a similar method to convert NIR scattered light to column density.…”

Section: Introductionmentioning

confidence: 99%

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Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N

Malinen

Juvela

Pelkonen

et al. 2013

A&A

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Context. Mapping of the near-infrared (NIR) scattered light is a recent method for the study of interstellar clouds, complementing other, more commonly used methods, like dust emission and extinction. Aims. Our goal is to study the usability of this method on larger scale, and compare the properties of a filamentary structure using infrared scattering and other methods. We also study the radiation field and differences in grain emissivity between diffuse and dense areas. Methods. We have used scattered NIR J, H, and K band surface brightness observations with WFCAM instrument to map a filament TMC-1N in Taurus Molecular Cloud, covering an area of 1We have converted the data into an optical depth map and compared the results with NIR extinction and Herschel observations of sub-mm dust emission. We have also modelled the filament with 3D radiative transfer calculations of scattered light. Results. We see the filament in scattered light in all three NIR bands. We note that our WFCAM observations in TMC-1N show notably lower intensity than previous results in Corona Australis using the same method. We show that 3D radiative transfer simulations predict similar scattered surface brightness levels as seen in the observations. However, changing the assumptions about the background can change the results of simulations notably. We derive emissivity, the ratio of FIR dust emission to column density, by using optical depth in the J band, τ J , obtained from NIR extinction map as an independent tracer of column density. We obtain a value 0.0013 for the ratio τ 250 /τNicer J . This leads to opacity or dust emission cross-section σ e (250 μm) values 1.7−2.4 × 10 −25 cm 2 /H, depending on assumptions of the extinction curve, which can change the results by over 40%. These values are twice as high as obtained for diffuse areas, at the lower limit of earlier results for denser areas. Conclusions. We show that NIR scattering can be a valuable tool in making high resolution maps. We conclude, however, that NIR scattering observations can be complicated, as the data can show comparatively low-level artefacts. This suggests caution when planning and interpreting the observations.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N

Malinen

Juvela

Pelkonen

et al. 2013

A&A

Self Cite

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“…Following these results, we assume the distance to the region to be 299 pc throughout this paper, which leads to a spatial resolution of 0.02 pc or 4200 au for the 14 1 JCMT beam at 850 μm (FWHM). The typical width of filaments suggested from Herschel observations is ∼0.1 pc (Arzoumanian et al 2011;Juvela et al 2012;Alves de Oliveira et al 2014;Koch & Rosolowsky 2015;Federrath 2016;Arzoumanian et al 2019), which can be well resolved by the JCMT beam. NGC 1333 is, therefore, a suitable area to study the relationship between filaments and B-fields over the whole star-forming area.…”

Section: Introductionmentioning

confidence: 72%

The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333

Doi¹,

Hasegawa

Furuya

et al. 2020

ApJ

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We present new observations of the active star formation region NGC 1333 in the Perseus molecular cloud complex from the James Clerk Maxwell Telescope B-Fields In Star-forming Region Observations (BISTRO) survey with the POL-2 instrument. The BISTRO data cover the entire NGC 1333 complex (∼1.5 pc×2 pc) at 0.02 pc resolution and spatially resolve the polarized emission from individual filamentary structures for the first time. The inferred magnetic field structure is complex as a whole, with each individual filament aligned at different position angles relative to the local field orientation. We combine the BISTRO data with low-and high-resolution data derived from Planck and interferometers to study the multiscale magnetic field structure in this region. The magnetic field morphology drastically changes below a scale of ∼1 pc and remains continuous from the scales of filaments (∼0.1 pc) to that of protostellar envelopes (∼0.005 pc or ∼1000 au). Finally, we construct simple models in which we assume that the magnetic field is always perpendicular to the long axis of the filaments. We demonstrate that the observed variation of the relative orientation between the filament axes and the magnetic field angles are well reproduced by this model, taking into account the projection effects of the magnetic field and filaments relative to the plane of the sky. These projection effects may explain the apparent complexity of the magnetic field structure observed at the resolution of BISTRO data toward the filament network.

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“…Grain size in dark clouds is an open subject that might improve with the combination of 3D radiative transfer dust models and A38, page 9 of 22 A&A 551, A38 (2013) diffraction observations from optical to mid-infrared (Steinacker et al 2010;Pagani et al 2010b;Juvela et al 2012). A standard grain size of 0.1 μm is usually assumed in chemical models, but this is a strong approximation that might not be valid.…”

Section: The Grain Size Impactmentioning

confidence: 99%

Ortho-H₂and the age of prestellar cores

Pagani

Lesaffre

Jorfi

et al. 2013

A&A

117

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Prestellar cores form from the contraction of cold gas and dust material in dark clouds before they collapse to form protostars. Several concurrent theories exist to describe this contraction but they are currently difficult to distinguish. One major difference is the timescale involved in forming the prestellar cores: some theories advocate nearly free-fall speed via, e.g., rapid turbulence decay, while others can accommodate much longer periods to let the gas accumulate via, e.g., ambipolar diffusion. To tell the difference between these theories, measuring the age of prestellar cores could greatly help. However, no reliable clock currently exists. We present a simple chemical clock based on the regulation of the deuteration by the abundance of ortho-H 2 that slowly decays away from the ortho-para statistical ratio of 3 down to or less than 0.001. We use a chemical network fully coupled to a hydrodynamical model that follows the contraction of a cloud, starting from uniform density, and reaches a density profile typical of a prestellar core. We compute the N 2 D + /N 2 H + ratio along the density profile. The disappearance of ortho-H 2 is tied to the duration of the contraction and the N 2 D + /N 2 H + ratio increases in the wake of the ortho-H 2 abundance decrease. By adjusting the time of contraction, we obtain different deuteration profiles that we can compare to the observations. Our model can test fast contractions (from 10 4 to 10 6 cm −3 in ∼0.5 My) and slow contractions (from 10 4 to 10 6 cm −3 in ∼5 My). We have tested the sensitivity of the models to various initial conditions. The slowcontraction deuteration profile is approximately insensitive to these variations, while the fast-contraction deuteration profile shows significant variations. We found that, in all cases, the deuteration profile remains clearly distinguishable whether it comes from the fast collapse or the slow collapse. We also study the para-D 2 H + /ortho-H 2 D + ratio and find that its variation is not monotonic, so it does not discriminate between models. Applying this model to L183 (=L134N), we find that the N 2 D + /N 2 H + ratio would be higher than unity for evolutionary timescales of a few megayears independently of other parameters, such as cosmic ray ionization rate or grain size (within reasonable ranges). A good fit to the observations is only obtained for fast contraction (≤0.7 My from the beginning of the contraction and ≤4 My from the birth of the molecular cloud based on the need to keep a high ortho-H 2 abundance when the contraction starts -ortho-H 2 /para-H 2 ≥ 0.2 -to match the observations). This chemical clock therefore rules out slow contraction in L183 and steady-state chemical models, since steady state is clearly not reached here. This clock should be applied to other cores to help distinguish slow and fast contraction theories over a large sample of cases.

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A Corona Australis cloud filament seen in NIR scattered light

Cited by 13 publications

References 94 publications

Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N

Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N

The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333

Ortho-H₂and the age of prestellar cores

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A Corona Australis cloud filament seen in NIR scattered light

Cited by 13 publications

References 94 publications

Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N

Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N

The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333

Ortho-H2and the age of prestellar cores

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Product

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Ortho-H₂and the age of prestellar cores