Probing the structure of a massive filament: ArTéMiS 350 and 450 μm mapping of the integral-shaped filament in Orion A

Abstract

Context. The Orion molecular cloud is the closest region of high-mass star formation. It is an ideal target for investigating the detailed structure of massive star-forming filaments at high resolution and the relevance of the filament paradigm for the earliest stages of intermediate-to high-mass star formation. Aims. Within the Orion A molecular cloud, the integral-shaped filament (ISF) is a prominent, degree-long structure of dense gas and dust with clear signs of recent and ongoing high-mass star formation. Our aim is to characterise the structure of this massive filament at moderately high angular resolution (8 or ∼ 0.016 pc) in order to measure the intrinsic width of the main filament, down to scales well below 0.1 pc, which has been identified as the characteristic width of filaments. Methods. We used the ArTéMiS bolometer camera at APEX to map a ∼0.6×0.2 deg 2 region covering OMC-1, OMC-2, and OMC-3 at 350 and 450 µm. We combined these data with Herschel-SPIRE maps to recover extended emission. The combined Herschel-ArTéMiS maps provide details on the distribution of dense cold material, with a high spatial dynamic range, from our 8 resolution up to the transverse angular size of the map, ∼ 10-15 . By combining Herschel and ArTéMiS data at 160, 250, 350, and 450 µm, we constructed high-resolution temperature and H 2 column density maps. We extracted radial intensity profiles from the column density map in several representative portions of the ISF, which we fitted with Gaussian and Plummer models to derive their intrinsic widths. We also compared the distribution of material traced by ArTéMiS with that seen in the higher-density tracer N 2 H + (1-0) that was recently observed with the ALMA interferometer. Results. All the radial profiles that we extracted show a clear deviation from a Gaussian, with evidence for an inner plateau that had not previously been seen clearly using Herschel-only data. We measure intrinsic half-power widths in the range 0.06 to 0.11 pc. This is significantly larger than the Gaussian widths measured for fibres seen in N 2 H + , which probably only traces the dense innermost regions of the large-scale filament. These half-power widths are within a factor of two of the value of ∼ 0.1 pc found for a large sample of nearby filaments in various low-mass star-forming regions, which tends to indicate that the physical conditions governing the fragmentation of pre-stellar cores within transcritical or supercritical filaments are the same over a large range of masses per unit length.

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): How Do Dense Core Properties Affect the Multiplicity of Protostars?

“…The higher core volume density reduces the Jeans length in the Orion B cloud, resulting in an overall higher CSF compared to the Orion A cloud. The northern part of Orion A, the ISF, however, stands out in the Orion complex due to its intense star formation (Megeath et al 2016) and extremely high gas density (Hacar et al 2018;Schuller et al 2021;Yun et al 2021). It is the most massive filament among the Gould Belt clouds (Bally et al 1987;Schuller et al 2021).…”

“…The northern part of Orion A, the ISF, however, stands out in the Orion complex due to its intense star formation (Megeath et al 2016) and extremely high gas density (Hacar et al 2018;Schuller et al 2021;Yun et al 2021). It is the most massive filament among the Gould Belt clouds (Bally et al 1987;Schuller et al 2021). The ISF region, with highmass star formation in its dense center (the ONC), shows the highest MF and CSF among the Orion GMCs.…”

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): How do dense core properties affect the multiplicity of protostars?

“…The higher core volume density reduces the Jeans length in the Orion B cloud, resulting in a overall higher CSF compared to the Orion A cloud. The northern part of Orion A, the integral-shaped filament (ISF), however, stands out in the Orion complex due to its intense star formation (Megeath et al 2016) and extremely high gas density (Hacar et al 2018;Schuller et al 2021;Yun et al 2021). It is the most massive filament among the Gould Belt clouds (Bally et al 1987;Schuller et al 2021).…”

“…The northern part of Orion A, the integral-shaped filament (ISF), however, stands out in the Orion complex due to its intense star formation (Megeath et al 2016) and extremely high gas density (Hacar et al 2018;Schuller et al 2021;Yun et al 2021). It is the most massive filament among the Gould Belt clouds (Bally et al 1987;Schuller et al 2021). The ISF region, with high-mass star formation in its dense center (Orion Nebula Cluster), shows highest MF and CSF among Orion GMCs.…”

The DR21(OH) Trident -- Resolving the Massive Ridge into Three Entangled Fibers As the Initial Condition of Cluster Formation

“…Located at a distance of 1.5 kpc (Rygl et al 2012), this structure has a projected length of ∼2.5 pc and a total gas mass of ∼9000 M , making its line mass two orders of magnitude higher than those of the low-mass filaments (e.g. Hill et al 2011;Hacar et al 2013) and about 10 times higher than that of the ISF in Orion (Schuller et al 2021). Given its relatively close distance and great mass, the DR21(OH) ridge is an ideal target for disentangling the substructures of high-mass cluster-forming HFSs.…”