J/ApJ/952/50 NOEMA observations of W3(H2O) and W3(OH) (Thompson+, 2023)
Comparing complex chemistry in neighboring hot cores: NOEMA studies of W3(H2O)
and W3(OH).
Thompson W.E., Giese M.M., Lis D.C., Widicus Weaver S.L.
<Astrophys. J., 952, 50 (2023)>
=2023ApJ...952...50T 2023ApJ...952...50T
ADC_Keywords: Interferometry; H II regions; Spectra, millimetric/submm;
Star Forming Region; Molecular data
Keywords: Astrochemistry ; Interferometry ; Star forming regions ; H II regions
Abstract:
Presented here are NOEMA interferometric observations of the
neighboring hot cores W3(H2O) and W3(OH). The presence of two
star-forming cores at different evolutionary stages within the same
parent cloud presents a unique opportunity to study how the physics of
the source and its evolutionary stage impact the chemistry. Through
spectral analysis and imaging, we identify over 20 molecules in these
cores. Most notably, we have detected HDO and CH3CH2CN in W3(OH),
which were previously not detected in this core. We have imaged the
molecular emission, revealing new structural features within these
sources. W3(OH) shows absorption in a "dusty cocoon" surrounded by
molecular emission. These observations also reveal extended emission
that is potentially indicative of a low-velocity shock. From the
information obtained herein, we have constructed column density and
temperature maps for methanol and compared this information to the
molecular images. By comparing the spatial distribution of molecules
that may be destroyed at later stages of star formation, this work
demonstrates the impact of physical environment on chemistry in
star-forming regions at different evolutionary stages.
Description:
W3 was observed with the IRAM/NOEMA interferometer in the C and D
configurations for ∼4hr in each configuration on 2021 August 21 and 26
and 2021 October 19. The pointing center of the observations was
RAJ2000=02:27:03.87,DEJ2000=61:52:24.6, so that the field of view
included emission from both the W3(H2O) and W3(OH) cores. The
observations were in the λ=2mm wavelength range, centered at a
local oscillator frequency of 145.255GHz with frequency coverage from
127.823 to 135.311GHz and from 143.116 to 150.666GHz for the lower and
upper sidebands, respectively.
The baselines of the array ranged from 24.0 to 176.0m in the 10D
configuration and from 24.0 to 368.0m in the 10C configuration.
See Section 2.
The continuum was imaged at 132GHz, as seen in Figure 1.
See Section 3.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
02 27 04.10 +61 52 21.9 W3(OH) = NAME W 3 OH
02 27 04.60 +61 52 24.9 W3(H2O) = W 3(H2O)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig2.dat 31 16176 Spectra of W3(H2O) and W3(OH)
fig3.dat 119 16376 *GOBASIC fit many molecules to the spectra of
W3(H2O) and W3(OH)
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Note on fig3.dat: In order to analyze the broadband spectra, the Global
Optimization and Broadband Analysis Software for Interstellar
Chemistry (GOBASIC) was used. The intricacies of this software are
described by Rad+ (2016, J/A+A/585/A23). See Section 4.
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See also:
B/iram/noema : IRAM Observation Logs (IRAM 1991-)
J/A+AS/124/205 : W3 star-forming region 345 GHz survey (Helmich+ 1997)
J/A+AS/132/211 : Interstellar SiO sources (Harju+ 1998)
J/A+A/358/257 : Molecular clouds SO and CS obs. II. (Nilsson+, 2000)
J/AZh/79/610 : Methyl acetylene observations of warm clouds (Alakoz+, 2002)
J/ApJ/647/418 : Ground-state OH masers in W3(OH) study (Fish+, 2006)
J/other/ChA+A/36.238 : Dense parts of outflows toward cores (Sun+, 2012)
J/A+A/563/A97 : IRAM 30m reduced spectra of 59 sources (Gerner+, 2014)
J/A+A/567/L5 : W3(OH) high angular resolution 7mm images (Dzib+, 2014)
J/ApJS/213/1 : The MSFRs Omnibus X-ray Catalog (MOXC) (Townsley+, 2014)
J/ApJS/232/3 : Spectral line surveys of 30 regions (Widicus Weaver+, 2017)
J/A+A/612/A37 : CH 149um spectra of 4 molecular clouds (Wiesemeyer+, 2018)
J/A+A/618/A46 : W3(H2O/OH) cont. & line data cubes at 1.3mm (Ahmadi+, 2018)
J/ApJ/897/L38 : Protostars excitation temperatures (Van't Hoff+, 2020)
J/A+A/682/A81 : CORE Sample NIKA2 and SMA images (Beuther+, 2024)
Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- ID Spectrum identifier ("W3-H2O" or "W3-OH")
9- 19 F11.4 MHz Freq [127398/150965] Observational spectrum frequency
21- 31 E11.4 K Temp [-31.1/50.3] Brightness temperature line intensity
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Byte-by-byte Description of file: fig3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- ID Spectrum identifier ("W3-H2O" or "W3-OH")
9- 19 F11.4 MHz Freq [127348/151015] Frequency
21- 31 E11.4 K ObsInt [-31.1/50.3] Intensity from the observational
spectrum
33- 42 E10.4 K PrevFit [0/23] Previous fits from molecules not
included in the table
44- 53 E10.4 K C2H5CN [0/4.7]? The CH3CH2CN molecule intensity,
W3(H2O) only
55- 64 E10.4 K CH3OH [0/41.3] The CH3OH molecule intensity
66- 75 E10.4 K CH3OCH3 [0/8.2] The CH3OCH3 molecule intensity
77- 86 E10.4 K HCOOCH3 [0/8.5] The HCOOCH3 molecule intensity
88- 97 E10.4 K SO2 [0/14] The SO2 molecule intensity
99- 108 E10.4 K CH3CN [0/19.4] The CH3CN molecule intensity
110- 119 E10.4 K TotalFit [0/41.3] Total intensity calculated fit from
all molecules
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 27-Aug-2025