J/A+A/644/A27 Musca APEX 12CO(2-1), 13CO(2-1) and C18O(2-1) data (Bonne+, 2020)
Formation of the Musca filament:
evidence for asymmetries in the accretion flow due to a cloud-cloud collision.
Bonne L., Bontemps S., Schneider N., Clarke S. D., Arzoumanian D., Fukui Y.,
Tachihara K., Csengeri T., Guesten R., Ohama A., Okamoto R., Simon R.,
Yahia H., Yamamoto H.
<Astron. Astrophys. 644, A27 (2020)>
=2020A&A...644A..27B 2020A&A...644A..27B (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Carbon monoxide
Keywords: ISM: structure - ISM: kinematics and dynamics -
ISM: individual objects: Musca - stars: formation - evolution
Abstract:
Dense molecular filaments are ubiquituous in the interstellar medium,
yet their internal physical conditions and the role of gravity,
turbulence, the magnetic field, radiation, and the ambient cloud
during their evolution remain debated.
We study the kinematics and physical conditions in the Musca filament,
the ambient cloud, and the Chamaeleon-Musca complex to constrain the
physics of filament formation.
We produced CO(2-1) isotopologue maps with the APEX telescope that cut
through the Musca filament. We further study a NANTEN2 12CO(1-6>0)
map of the full Musca cloud, HI emission of the Chamaeleon-Musca
complex, a Planck polarisation map, line radiative tranfer models,
Gaia data, and synthetic observations from filament formation
simulations.
The Musca cloud, with a size of ∼3-6pc, contains multiple velocity
components. Radiative transfer modelling of the CO emission indicates
that the Musca filament consists of a cold (∼10K), dense
(nH2∼104cm-3) crest, which is best described with a cylindrical
geometry. Connected to the crest, a separate gas component at T∼15K
and nH2∼103cm-3 is found, the so-called strands. The
velocity-coherent filament crest has an organised transverse velocity
gradient that is linked to the kinematics of the nearby ambient cloud.
This velocity gradient has an angle ≥30° with respect to the
local magnetic field orientation derived from Planck, and the
magnitude of the velocity gradient is similar to the transonic
linewidth of the filament crest. Studying the large scale kinematics,
we find coherence of the asymmetric kinematics from the 50pc HI cloud
down to the Musca filament. We also report a strong [C18O]/[13CO]
abundance drop by an order of magnitude from the filament crest to the
strands over a distance <0.2pc in a weak ambient far-ultraviolet (FUV)
field.
The dense Musca filament crest is a long-lived (several crossing
times), dynamic structure that can form stars in the near future
because of continuous mass accretion replenishing the filament. This
mass accretion on the filament appears to be triggered by a HI
cloud-cloud collision, which bends the magnetic field around dense
filaments. This bending of the magnetic field is then responsible for
the observed asymmetric accretion scenario of the Musca filament,
which is, for instance, seen as a V-shape in the position-velocity
(PV) diagram.
Description:
The 12CO(2-1), 13CO(2-1) and C18O(1-0) spectral maps at the
northern and southern location of the Musca filament. All data files
are presented in FITS format with a spectral resolution of 0.1km/s.
The units are Ta* in K.
Objects:
-------------------------------------------------------
RA (2000) DE Designation(s)
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10 54 -74.0 Musca Filament = NAME Musca Filament
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 162 6 List of datacubes
fits/* . 6 Individual datacubes
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See also:
J/A+A/641/A17 : Musca APEX 12CO(2-1), 12CO(3-2) + 12CO(4-3) data (Bonne+, 2020)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 21 I2 --- Nx Number of pixels along X-axis
23- 24 I2 --- Ny Number of pixels along Y-axis
26- 28 I3 --- Nz Number of slices
30- 35 I6 m/s bVRAD Lower value of VRAD interval
37- 41 I5 m/s BVRAD Upper value of VRAD interval
43- 45 I3 m/s dVRAD VRAD resolution
47- 50 I4 Kibyte size Size of FITS file
52- 89 A38 --- FileName Name of FITS file, in subdirectory fits
91-162 A72 --- Title Title of the FITS file
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Acknowledgements:
Lars Bonne, lars.bonne(at)u-bordeaux.fr
(End) Lars Bonne [LAB, France], Patricia Vannier [CDS] 10-Nov-2020