J/A+A/627/A85 8 massive proto-cluster clumps observations (Zhang+, 2019)
Probing the initial conditions of high-mass star formation.
III. Fragmentation and triggered star formation.
Zhang C.-P., Csengeri T., Wyrowski F., Li G.-X., Pillai T., Menten K.M.,
Hatchell J., Thompson M.A., Pestalozz M.R.
<Astron. Astrophys. 627, A85 (2019)>
=2019A&A...627A..85Z 2019A&A...627A..85Z (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interferometry ; Radio sources ;
Millimetric/submm sources
Keywords: stars formation - techniques interferometer - ISM clouds -
methods: observational
Abstract:
Massive clumps tend to fragment into clusters of cores and
condensations, some of which form high-mass stars. In this work, we
study the structure of massive clumps at different scales, analyze the
fragmentation process, and investigate the possibility that star
formation is triggered by nearby HII regions. We present a high
angular resolution study of a sample of 8 massive proto-cluster
clumps. Combining infrared data, we use few-arcsecond resolution
radio- and millimeter interferometric data to study their
fragmentation and evolution. Our sample is unique in the sense that
all the clumps have neighboring HII regions. Taking advantage of that,
we test triggered star formation using a novel method where we study
the alignment of the centres of mass traced by dust emission at
multiple scales. The eight massive clumps have masses ranging from 228
to 2279M☉. The brightest compact structures within infrared
bright clumps are typically associated with embedded compact radio
continuum sources. The smaller scale structures of Reff∼0.02pc
observed within each clump are mostly gravitationally bound and
massive enough to form at least a B3-B0 type star. Many condensations
have masses larger than 8M☉ at small scale of Reff∼0.02pc.
Although the clumps are mostly infrared quiet, the dynamical movements
are active at clump scale (∼1pc). We studied the spatial distribution
of the gas conditions detected at different scales. For some sources
we find hints of external triggering, whereas for others we find no
significant pattern that indicates triggering is dynamically
unimportant. This probably indicates that the different clumps go
through different evolutionary paths. In this respect, studies with
larger samples are highly desired.
Description:
We present a high angular resolution study of a sample of massive
proto-cluster clumps G18.17, G18.21, G23.97N, G23.98, G23.44, G23.97S,
G25.38, and G25.71. Combining infrared data at 4.5, 8.0, 24, and 70um,
we use a few arcsecond resolution, radiometer and millimeter
inteferometric data taken at 1.3cm, 3.5mm, 1.3mm, and 870um to study
their fragmentation and evolution. Our sample is unique in the sense
that all the clumps have neighboring HII regions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 117 12 Parameters of PdBI observations
table2.dat 57 8 Parameters of VLA NH3 (1,1) observations
table3.dat 79 11 The properties of infrared data
table4.dat 137 28 Clump parameters derived from 450, 850, and
870micron observations
table5.dat 137 56 Fragment parameters derived from
PdBI 3.5mm observations
table6.dat 137 53 Fragment parameters derived from
PdBI 1.3mm observations
list.dat 116 56 List of fits files
fits/* . 56 Individual fits files for the 8 sources
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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 A3 --- Conf Configuration observation (CD or BCD)
5- 11 A7 --- Source Source name
13- 28 A16 --- ATLASGAL ATLASGAL name (GLLL.llll+B.bbbb)
30- 31 I2 h RAh Phase center right ascension (J2000)
33- 34 I2 min RAm Phase center right ascension (J2000)
36- 41 F6.3 s RAs Phase center right ascension (J2000)
43 A1 --- DE- Phase center declination sign (J2000)
44- 45 I2 deg DEd Phase center declination (J2000)
47- 48 I2 arcmin DEm Phase center declination (J2000)
50- 54 F5.2 arcsec DEs Phase center declination (J2000)
56- 59 F4.2 arcsec 3.5beama 3.5mm beam major axis
60 A1 --- --- [x]
61- 64 F4.2 arcsec 3.5beamb 3.5mm beam minor axis
66- 70 F5.2 deg 3.5beamPA 3.5mm beam position angle
72- 75 F4.2 mJy/beam 3.5rms 3.5mm rms
77- 80 F4.2 arcsec 1.3beama 1.3mm beam major axis
81 A1 --- --- [x]
82- 85 F4.2 arcsec 1.3beamb 1.3mm beam minor axis
87- 91 F5.2 deg 1.3beamPA 1.3mm beam position angle
93- 96 F4.2 mJy/beam 1.3rms 1.3mm rms
98-117 A20 --- Obs.date Observation dates
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Conf Configuration observation (D)
5- 11 A7 --- Source Source name
13- 14 I2 h RAh Phase center right ascension (J2000)
16- 17 I2 min RAm Phase center right ascension (J2000)
19- 24 F6.3 s RAs Phase center right ascension (J2000)
26 A1 --- DE- Phase center declination sign (J2000)
27- 28 I2 deg DEd Phase center declination (J2000)
30- 31 I2 arcmin DEm Phase center declination (J2000)
33- 37 F5.2 arcsec DEs Phase center declination (J2000)
39- 42 F4.2 arcsec NH3beama VLA NH3 (1,1) beam major axis
43 A1 --- --- [x]
44- 47 F4.2 arcsec NH3beamb VLA NH3 (1,1) beam minor axis
49- 53 F5.2 deg NH3beamPA VLA NH3 (1,1) beam position angle
55- 57 F3.1 mJy/beam NH3rms VLA NH3 (1,1) rms
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Source Source name
8 A1 --- n_Source [ul] Note on Source (1)
10- 14 F5.1 mJy S4.5um ? Flux density at 4.5um
16- 18 F3.1 mJy e_S4.5um ? rms uncertainty on flux density at 4.5um
20- 25 F6.1 mJy S8.0um ? Flux density at 8.0um
27- 30 F4.1 mJy e_S8.0um ? rms uncertainty on flux density at 8.0um
32- 38 F7.1 mJy S24um ? Flux density at 24um
40- 44 F5.1 mJy e_S24um ? rms uncertainty on flux density at 24um
46- 50 F5.1 mJy S70um ? Flux density at 70um
52- 54 F3.1 mJy e_S70um ? rms uncertainty on flux density at 70um
56- 61 A6 --- IR Infrared (bright or quiet) (2)
62 A1 --- n_IR [d] Note (3)
64- 66 A3 --- HII [yes/no ] HII region ? (4)
68 A1 --- n_HII [d] Note (3)
70- 73 F4.2 kpc Dist Distance
75- 79 A5 --- r_Dist Reference(s) for distance (5)
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Note (1): The l and u indicate the lower and upper clusters in corresponding
clumps.
Note (2): Mainly based on a threshold of MIPS 24micron flux S24um=15.0Jy at a
distance of 1.7kpc (Motte et al., 2007, Cat. J/A+A/476/1243), this flux limit
can be rescaled to the distance of the sources in this table.
Note (3): Compact HII region candidate, judged by whether there is a
corresponding 1.3cm continuum at its sensitivity.
Note (4): G23.97S is actually associated with the very weak infrared source at
the north of the bright one, so it is an infrared quiet source. However,
1.3cm continuum was detected so it belongs to an HII region.
Note (5): References for distance as follows:
1 = Wienen et al., 2012, Cat. J/A+A/544/A146
2 = Reid et al., 2009ApJ...700..137R 2009ApJ...700..137R
3 = Brunthaler et al., 2009ApJ...693..424B 2009ApJ...693..424B
4 = Anderson & Bania, 2009, Cat. J/ApJ/690/706
5 = Ai et al., 2013RAA....13..935A 2013RAA....13..935A
6 = Urquhart et al., 2013, Cat. J/MNRAS/435/400
7 = Lockman, 1989ApJS...71..469L 1989ApJS...71..469L, Cat. VIII/58
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Byte-by-byte Description of file: table4.dat table5.dat table6.dat
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Bytes Format Units Label Explanations
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1- 5 A5 um Band Observed band
(450um, 850um, 870um, 1.3mm or 3.5mm)
7- 9 A3 --- Conf [CD BCD] Configuration observation
11- 17 A7 --- Source Source name
19- 20 I2 --- No Clump or fragment sequential number
within the Source
21 A1 --- n_No [ab] Note on No (1)
23- 28 F6.2 arcsec OffRA Offset in right ascension
30- 35 F6.2 arcsec OffDE Offset in declination
37- 41 F5.2 arcsec FWHM FWHM
43- 47 F5.3 pc Reff Effective radius
49- 52 F4.1 K Tkin Kinematical temperature
54- 57 F4.1 K e_Tkin rms uncertainty on kinematical temperature
59- 63 F5.2 Jy/beam Ipeak Peak intensity at Band
65- 70 F6.2 Jy Sint Integrated intensity at Band
72- 75 F4.1 % Cdust ? Dust contribution (only in table 5)
77- 82 F6.1 Msun Mass Mass
84- 89 F6.1 Msun e_Mass rms uncertainty on mass
91- 94 F4.1 10+23cm-2 NH2 H2 column density
96- 98 F3.1 10+23cm-2 e_NH2 rms uncertainty on H2 column density
100-102 F3.1 g/cm2 Sigma Mass surface density {SIGMA}
104-106 F3.1 g/cm2 e_Sigma rms uncertainty on Sigma
108-111 F4.1 10+5cm-3 nH2 H2 density number
113-116 F4.1 10+5cm-3 e_nH2 rms uncertainty on H2 density number
118-121 F4.2 km/s DVNH3 NH3 line width
123-126 F4.2 km/s e_DVNH3 rms uncertainty on DVNH3
128-132 F5.1 Msun Mvir Viral mass
134-137 F4.1 Msun e_Mvir rms uncertainty on Viral mass
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Note (1): Flag as follow:
a = The contributions from dust emission are following a measured total flux,
e.g., 40.8% of the 3.5mm flux for G23.44-1 is from dust emission.
This was estimated by SED fitting.
b = The sources G23.44-1, G23.97S-1, G25.71-1, and G25.71-2 are clearly
associated with compact HII regions.
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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- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 31 I4 Kibyte size Size of FITS file
33- 53 A21 --- FileName Name of FITS file, in subdirectory fits
55- 61 A7 --- Source Source name
63-116 A54 --- Title Title of the FITS file
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Acknowledgements:
Chuan-Peng Zhang, zcp0507(at)gmail.com
References:
Pillai et al., Paper I 2007A&A...467..207P 2007A&A...467..207P
Pillai et al., Paper II 2011A&A...530A.118P 2011A&A...530A.118P, Cat. J/A+A/530/A118
(End) Chuan-Peng Zhang [Heidelberg], Patricia Vannier [CDS] 20-Jun-2019