J/ApJ/939/84 Complex organic molecules in high-mass SFRs with ALMA (Baek+, 2022)
Complex organic molecules detected in 12 high-mass star-forming regions with
Atacama Large Millimeter/submillimeter Array.
Baek G., Lee J.-E., Hirota T., Kim K.-T., Kyoung Kim Mi
<Astrophys. J., 939, 84 (2022)>
=2022ApJ...939...84B 2022ApJ...939...84B
ADC_Keywords: Star Forming Region; Molecular data; Masers;
Millimetric/submm sources
Keywords: Interstellar masers ; Astrochemistry ; Interstellar molecules ;
Massive stars ; Star formation ; Chemical abundances
Abstract:
Recent astrochemical models and experiments have explained that
complex organic molecules (COMs; molecules composed of six or more
atoms) are produced on the dust grain mantles in cold and dense gas in
prestellar cores. However, the detailed chemical processes and the
roles of physical conditions on chemistry are still far from
understood. To address these questions, we investigated 12 high-mass
star-forming regions using Atacama Large Millimeter/submillimeter
Array (ALMA) Band 6 observations. They are associated with 44/95GHz
class I and 6.7GHz class II CH3OH masers, indicative of undergoing
active accretion. We found 28 hot cores with COM emission among 68
continuum peaks at 1.3mm and specified 10 hot cores associated with
6.7GHz class II CH3OH masers. Up to 19 COMs are identified including
oxygen- and nitrogen-bearing molecules and their isotopologues in
cores. The derived abundances show a good agreement with those from
other low- and high-mass star-forming regions, implying that the COM
chemistry is predominantly set by the ice chemistry in the prestellar
core stage. One clear trend is that the COM detection rate steeply
grows with the gas column density, which can be attributed to the
efficient formation of COMs in dense cores. In addition, cores
associated with a 6.7GHz class II CH3OH maser tend to be enriched
with COMs. Finally, our results suggest that the enhanced abundances
of several molecules in our hot cores could be originated by the
active accretion as well as different physical conditions of cores.
Description:
ALMA observations in Band 6 (1.1-1.4mm; 211-275GHz) were carried out
(2015.1.01571.S: P.I. M.-K. Kim) toward 12 high-mass star-forming
regions (HMSFRs). The observation and target information is summarized
in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 12 Summary of observation and target information
table2.dat 122 68 Summary of core detection in 1.3mm continuum
table3.dat 88 28 Summary of information at the peak of 216.946GHz
CH3OH emission
table4.dat 27 63 Methanol maser emission and hot core associations
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See also:
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/MNRAS/301/640 : Ultracompact H II regions studies. II. (Walsh+, 1998)
J/A+A/403/1095 : 6.7GHz methanol masers survey of YSOs (Minier+, 2003)
J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)
J/ApJ/702/1615 : CH3OH maser survey of EGOs (Cyganowski+, 2009)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/MNRAS/446/3461 : 6.7-GHz methanol masers-dust associations (Urquhart+, 2015)
J/A+A/579/A91 : ATLASGAL inner Gal. massive cold dust clumps (Wienen+, 2015)
J/ApJ/833/18 : Ultra-compact HII regions & methanol masers. I. (Hu+, 2016)
J/A+A/601/A49 : CH3NHCHO rotational spectroscopy (Belloche+, 2017)
J/ApJ/839/108 : YSOs in the star-forming regions W51 & W43 (Saral+, 2017)
J/A+A/632/A57 : G328.2551-0.5321 spectra (Csengeri+, 2019)
J/ApJ/883/129 : Star-forming regions toward NGC6334I (El-Abd+, 2019)
J/A+A/632/A19 : IRAM intensity maps of 3 low-mass protostars (Taquet+ 2019)
J/ApJ/900/L10 : The GOTHAM Large Project for TMC-1 (McGuire+, 2020)
J/A+A/639/A87 : Complex organic mol. in protostars (van Gelder+, 2020)
J/A+A/659/A69 : Di-deuterated methanol line list (Drozdovskaya+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Reg Target name
15 A1 --- f_Reg [e] E=region observed from offset of the
phase center
17- 18 I2 h RAh Phase center of observation hour of right
ascension (J2000)
20- 21 I2 min RAm Phase center of observation minute of right
ascension (J2000)
23- 27 F5.2 s RAs Phase center of observation second of right
ascension (J2000)
29 A1 --- DE- Phase center of observation sign of
declination (J2000) (2)
30- 31 I2 deg DEd Phase center of observation degree of
declination (J2000) (2)
33- 34 I2 arcmin DEm Phase center of observation arcminute of
declination (J2000)
36- 39 F4.1 arcsec DEs Phase center of observation arcsecond of
declination (J2000)
41- 46 F6.2 arcsec RAOff [-13.8/5.1] RA position offset from the phase
center to the strongest continuum peak of the
target
48- 53 F6.2 arcsec DEOff [-4.15/13.6] DEC position offset from the
phase center to the strongest continuum peak
of the target
55 A1 --- f_DEOff [d] Flag on DEOff (1)
57- 63 E7.2 Jy/beam rms [4.5e-05/0.003] rms values (2)
65- 67 F3.1 kpc Dist [1.6/8] Distance
69- 72 A4 --- r_Dist Reference (3)
74 A1 --- frDist Flag on r_Dist (1)
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Note (1): Flag as follows:
c = The distance is assumed to be the same as that of G18.34+1.78.
d = G23.43-0.18 is observed toward the G23.43-0.18 C2 for the pointing
center, southern from the strongest continuum peak at C1.
Note (2): rms values of primary beam uncorrected continuum images are presented
to estimate the sensitivity of the observation.
Note (3): Reference as follows:
B09 = Brunthaler et al. (2009ApJ...693..424B 2009ApJ...693..424B)
BT12 = Butler & Tan (2012ApJ...754....5B 2012ApJ...754....5B)
H22 = Hirota et al. (2022PASJ...74.1234H 2022PASJ...74.1234H)
K20 = Kim et al. (2020ApJ...896..127K 2020ApJ...896..127K)
R14 = Reid et al. (2014, J/ApJ/783/130)
R16 = Reid et al. (2016ApJ...823...77R 2016ApJ...823...77R)
S17 = Saral et al. (2017, J/ApJ/839/108)
T17 = Towner et al. (2017ApJS..230...22T 2017ApJS..230...22T)
U15 = Urquhart et al. (2015, J/MNRAS/446/3461)
W15 = Wienen et al. (2015, J/A+A/579/A91)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Reg Region name as in Table 1
14- 16 A3 --- Core Core identifier within Reg
18- 19 I2 h RAh Hour of right ascension (J2000)
21- 22 I2 min RAm Minute of right ascension (J2000)
24- 28 F5.2 s RAs Second of right ascension (J2000)
30 A1 --- DE- Sign of declination (J2000)
31- 32 I2 deg DEd Degree of declination (J2000)
34- 35 I2 arcmin DEm Arcminute of declination (J2000)
37- 40 F4.1 arcsec DEs Arcsecond of declination (J2000)
42- 44 I3 --- S/N [5/705] Signal-to-noise ratio (1)
46- 50 F5.1 mJy/beam Spk [1.7/600.5] Peak intensity
52- 54 F3.1 mJy/beam e_Spk [0.1/4] Spk uncertainty
56- 61 F6.2 K Tb [0.58/144] Brightness temperature
63- 69 E7.3 cm-2 NH2 [1.6e+22/2.7e+25] Hydrogen column density,
NH2 (2)
71- 77 E7.3 cm-2 e_NH2 [5e+22/10e+25] Lower uncertainty on NH2
79- 85 E7.3 cm-2 E_NH2 [5e+22/10e+25] Upper uncertainty on NH2
87- 89 F3.1 arcsec Size1 [0.3/0.8] Convolved source size
91- 93 F3.1 arcsec Size2 [0.2/0.7] Convolved source size
95- 99 F5.1 deg PA [0.4/174.9] Position angle convolved source size
101- 104 I4 mJy Fden [2/2118] Flux density
106- 109 F4.1 mJy e_Fden [0.2/11.5] Fden uncertainty
111- 115 F5.1 Msun Mtot1 [0.1/173.5] Total mass lower range (3)
117- 122 F6.1 Msun Mtot2 [0.7/2553.2] Total mass upper range (3)
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Note (1): The S/N is measured in primary-beam-uncorrected images.
Note (2): For N(H2), we adopt Tex(CH3OH), which is derived from the
rotation diagram of CH3OH for complex organic molecules (COMs)
-detected cores. Note that Tex(CH3OH) is derived at the CH3OH
emission peak located off from the continuum peak where the high dust
optical depth affects the line intensity. The actual Tex(CH3OH)
would be higher than the adopted temperature. The Tdust and Tgas are
assumed to be the same. For COM-undetected continuum peaks, a range of
Tdust temperature of 20-100K is adopted for prestellar to protostellar
cores, assuming that the cores without COM emission are cooler than
those with COM emission.
Note (3): The lower and upper limits are derived. For all components, the
lowest average temperature is assumed to be 20K to provide the upper
limit of the total mass. For COM-detected cores (Table 4),
Tex(CH3OH) is adopted (Table 5). The actual average temperature of
each core would be lower than the derived Tex(CH3OH), which is
measured at the CH3OH peak position; thus the derived mass is the
lower limit. For COM-undetected continuum components, the highest
temperature of 100K is assumed for the lower mass limit.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Reg Region name as in Table 1
14- 16 A3 --- Core Core identifier within Reg
18- 19 I2 h RAh Hour of right ascension (J2000)
21- 22 I2 min RAm Minute of right ascension (J2000)
24- 28 F5.2 s RAs Second of right ascension (J2000)
30 A1 --- DE- Sign of declination (J2000)
31- 32 I2 deg DEd Degree of declination (J2000)
34- 35 I2 arcmin DEm Arcminute of declination (J2000)
37- 41 F5.2 arcsec DEs Arcsecond of declination (J2000)
43- 49 E7.3 cm-2 NH2 [3.9e+23/1.3e+25] Hydrogen column density,
N(H2) (1)
51- 57 E7.3 cm-2 e_NH2 [4.2e+22/3.5e+23] Lower uncertainty on NH2
59- 65 E7.3 cm-2 E_NH2 [4.5e+22/4.5e+23] Upper uncertainty on NH2
67- 71 F5.1 km/s nuPk [9.8/113] Peak intensity, νpeak
73- 76 F4.1 km/s DelVoff [-6/4.1] Peak intensity,
Δνoffset
78- 82 F5.1 mJy/beam Ipk [10/603] Peak intensity, Ipeak
84- 88 F5.1 K Tb [3.3/142.3] Peak intensity, Tb
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Note (1): N(H2) is obtained by the 1.3mm dust continuum image at which
the spectrum is extracted.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Reg Region name as in Table 1
14- 16 A3 --- Core Core identifier within Reg
18- 22 A5 --- em 216.946GHz CH3OH emission (1)
24 A1 --- mas 6.7GHz class II CH3OH maser (2)
26- 27 I2 --- Ncom [1/19]? Number of detected complex organic
molecules (COMs) (3)
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Note (1): Abreviations as follows:
TH = Thermal emission
M? = 216.946GHz methanol maser candidate; maser detection was not firmly
confirmed despite evident spot emission features.
N = no CH3OH emission detected.
Note (2): Green+ (2010, VIII/96), Breen+ (2015MNRAS.450.4109B 2015MNRAS.450.4109B), and
Hu+ (2016, J/ApJ/833/18).
Note (3): The number of COMs identified using XCLASS. There are detected
but unidentified lines; thus the number is a lower limit.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 20-Mar-2025