J/A+A/693/A21 W3/4 clump properties from 13CO dendrogram leaves (Shen+, 2025)
Triggered and dispersed under feedback of super HII region W4.
Shen H., Esimbek J., Henkel C., Li D., Zhou J., He Y., Tang X., Wu G.,
Komesh T., Tursun K., Zhou D., Sailanbek S., Berdikhan D.
<Astron. Astrophys. 693, A21 (2025)>
=2025A&A...693A..21S 2025A&A...693A..21S (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Carbon monoxide ; Radio lines ; Morphology ;
Velocity dispersion
Keywords: methods: observational - ISM: clouds - ISM: HII regions -
ISM: kinematics and dynamics - ISM: structure
Abstract:
The W3/4 Giant Molecular Cloud (GMC) is an ideal target to study the
impact of HII regions onto the surrounding molecular gas and star
formation. We utilized PMO CO (1-0) data from the Milky Way Imaging
Scroll Painting (MWISP) survey to analyze the cloud structure and the
feedback effect from the W4 HII region. Our observations show that
cold gas, traced by CO, mainly resides in the W3 GMC, with C18O
concentrated in dense regions, while gas around W4 is dispersed. The
13CO position-position-velocity (PPV) distributions reveal a C
shaped structure in the W3 cloud with more redshifted gas at higher
galactic longitudes. A high density layer (HDL) region on the eastern
side of the W3 region exhibits a flattened structure facing W4.
Subdividing the area into sixteen subregions, we find that regions 6-9
on the HDL layer exhibit the strongest radiation, while clouds at the
W4 bubble boundary not facing W3 exhibit weak signals, possibly due to
star formation triggering and subsequent molecular gas dispersal by
the HII region. Analysis along four paths from the W4 HII region to
the far side shows a consistent trend of sharply increasing intensity
followed by a slow decrease, indicating the gas is effectively eroded
and heated by the photon dominated region (PDR) near the boundary of
the HII region. Clump identification based on 13CO emission reveals
288 structures categorized as bubble, HDL, and quiescent clumps.
Analysis of mass- radius and Virial-mass relationships show a
potential for high-mass star formation in 29.5% (85/288) of the
clumps, with 39.2% (113/288) being gravitationally bound. HDL clumps
exhibit distinct L/M and velocity dispersion, suggesting an earlier
evolutionary stage and gravitational instability compared to quiescent
and bubble clumps. Clump parameter differences provide evidence for
triggered and dispersed effects of the W4 HII region on the HDL and
bubble regions, respectively.
Description:
The properties of 288 identified 13CO clumps. Using CO data from the
survey MWISP project, we studied the gas structure distribution of the
W3/4 molecular clouds complex and the feedback effect of OB stars at
the center of the W4 HII region on molecular cloud gas. To analyze the
effects of HII region feedback on star formation in molecular clouds,
we identified clumps on 13CO cube data and performed a detailed
analysis of these clump parameters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 288 13CO clump properties derived from dendrogram
leaves of W3/4
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [0/328] Leaf number
5- 10 F6.2 deg GLON Galactic longitude
12- 16 F5.2 deg GLAT Galactic latitude
18- 22 F5.1 km/s Vmean Mean velocity of the structure
24- 26 F3.1 km/s FWHM FWHM line width
28- 31 F4.2 pc Radius Leaf radius
33- 37 F5.1 Lsun Lum Luminosity
39- 43 F5.2 10+22cm-2 N(H2) H2 column density
45- 51 F7.1 Msun M(LTE) LTE mass
53- 60 F8.1 Msun Mvir Virial mass
62- 66 F5.1 --- alphavir Virial parameter
68- 72 F5.2 10+4cm-3 n(H2) Volume density
74- 77 F4.2 Msun/pc2 Sigma Surface mass density
79- 83 F5.2 10-3Lsun/Msun L/M The ratio of luminosity to LTE mass
85- 88 F4.1 K Tex CO excitation temperature
90- 93 F4.2 km/s Vtherm Thermal velocity dispersion
95- 98 F4.2 km/s Vntherm Non-thermal velocity dispersion
100-103 F4.1 --- Vntherm/Vtherm The ratio of Vnthermal/vthermal
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History:
From Hailiang Shen, shenhailiang(at)xao.ac.cn
Acknowledgements:
We would like to thank the staff of the Purple Mountain Observatory
for their assistance with the 13.7m millimeter telescope observations.
This work was supported by the National Key R&D Program of China
(Grant No. 2022YFA1603103). We are grateful to Dr. Christian Henkel
for his valuable comments and suggestions. Special thanks to the
VizieR team for their guidance on data submission.
(End) Patricia Vannier [CDS] 15-Nov-2024