J/A+A/676/A69 G333 giant molecular cloud complex moment maps (Zhou+, 2023)
High-resolution APEX/LAsMA 12CO and 13CO (3-2) observation of the G333
giant molecular cloud complex.
I. Evidence for gravitational acceleration in hub-filament systems.
Zhou J.W., Wyrowski F., Neupane S., Urquhart J.S., Evans II N.J.,
Vazquez-Semadeni E., Menten K.M., Gong Y., Liu T.
<Astron. Astrophys. 676, A69 (2023)>
=2023A&A...676A..69Z 2023A&A...676A..69Z (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Carbon monoxide ; Radio lines
Keywords: ISM: kinematics and dynamics - methods: data analysis - ISM: clouds -
surveys - stars: formation - submillimeter: ISM
Abstract:
Hub-filament systems are suggested to be the birth cradles of
high-mass stars and clusters.
We investigate the gas kinematics of hub-filament structures in the
G333 giant molecular cloud complex using 13CO (3-2) observed
with the APEX/LAsMA heterodyne camera.
We applied the FILFINDER algorithm to the integrated intensity maps of
the 13CO J=3-2 line to identify filaments in the G333 complex, and
we extracted the velocity and intensity along the filament skeleton
from moment maps. Clear velocity and density fluctuations are seen
along the filaments, allowing us to fit velocity gradients around the
intensity peaks.
The velocity gradients we fit to the LAsMA and ALMA data agree with
each other over the scales covered by ALMA observations in the ATOMS
survey (<5pc). Changes in velocity gradient with scale indicate a
funnel structure of the velocity field in position-position-velocity
(PPV) space. This is indicative of a smooth, continuously increasing
velocity gradient from large to small scales, and thus is consistent
with gravitational acceleration. The typical velocity gradient
corresponding to a 1pc scale is ∼1.6km/s/pc. Assuming freefall, we
estimate a kinematic mass within 1pc of ∼1190M☉, which is
consistent with typical masses of clumps in the ATLASGAL survey of
massive clumps in the inner Galaxy. We find direct evidence for
gravitational acceleration from a comparison of the observed
accelerations to those predicted by freefall onto dense hubs with
masses from millimeter continuum observations. On large scales, we
find that the inflow may be driven by the larger-scale structure,
consistent with the hierarchical structure in the molecular cloud and
gas inflow from large to small scales. The hub-filament structures at
different scales may be organized into a hierarchical system extending
up to the largest scales probed through the coupling of gravitational
centers at different scales.
We argue that the funnel structure in PPV space can be an effective
probe for the gravitational collapse motions in molecular clouds. The
large-scale gas inflow is driven by gravity, implying that the
molecular clouds in the G333 complex may be in a state of global
gravitational collapse.
Description:
The analysis of this work bases on the Moment maps.
We mapped a 3.4°x1.2° area centered on
(l, b) = (332.33°, -0.29°). The observations were conducted
between March and August 2022 using the APEX telescope.
Objects:
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RA (2000) DE Designation(s)
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16 22 10.93 -50 05 38.4 G333 = GAL 333.6-00.2
16 12 09.79 -51 27 06.0 G331 = GAL 331.5-00.1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 94 2 List of fits images
fits/* . 2 Individual fits images
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1 A1 --- --- [G]
2- 10 F9.5 deg GLON Galactic longitude of center (J2000)
11- 19 F9.5 deg GLAT Galactic latitude of center (J2000)
21- 24 I4 --- Nx Number of pixels along X-axis
26- 28 I3 --- Ny Number of pixels along Y-axis
30- 34 I5 Kibyte size Size of FITS file
36- 50 A15 --- FileName Name of FITS file, in subdirectory fits
52- 94 A43 --- Title Title of the FITS file
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Acknowledgements:
Jian-wen Zhou, jwzhou(at)mpifr-bonn.mpg.de
(End) Patricia Vannier [CDS] 26-Jun-2023