J/A+A/684/A144 Ammonia observations of Planck cold cores (Berdikhan+, 2024)
Ammonia observations of Planck cold cores.
Berdikhan D., Esimbek J., Henkel C., Zhou J., Tang X., Liu T., Wu G., Li D.,
He Y., Komesh T., Tursun K., Zhou D., Imanaly E., Jandaolet Q.
<Astron. Astrophys. 684, A144 (2024)>
=2024A&A...684A.144B 2024A&A...684A.144B (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium; Radial velocities ; Radio lines ; Surveys
Keywords: surveys - stars: formation - ISM: clouds -
ISM: kinetics and dynamics - ISM: molecules
Abstract:
Single-pointing observations of NH3(1,1) and (2,2) were conducted
toward 672 Planck Early Cold Cores (ECCs) using the Nanshan 26-m radio
telescope. Out of these sources, a detection rate of 37 (249 cores)
was achieved, with a NH3(1,1) hyperfine structure detected in 187
cores and NH3(2,2) emission lines detected in 76 of them. The
detection rate of NH3 is positively correlated with the continuum
emission fluxes at a frequency of 857GHz. Among the observed 672
cores, ∼22 have associated stellar and infrared objects within the
beam size (∼2 arcmin). This suggests that most of the cores in our
sample may be starless. The kinetic temperatures of the cores range
from 8.9 to 20.7K, with an average of 12.3K, indicating a coupling
between gas and dust temperatures. The ammonia column densities range
from 3.6*1014 to 6.07*1015cm-2, with a median value of
2.04*1015cm-2^. The fractional abundances of ammonia range from 0.3
to 9.7*10-7, with an average of 2.7*10-7, which is one order of
magnitude larger than that of massive star-forming (MSF) regions and
infrared dark clouds (IRDCs). The correlation between thermal and
nonthermal velocity dispersion of the NH3(1,1) inversion transition
indicates the dominance of supersonic nonthermal motions in the dense
gas traced by NH3, and the relationship between these two parameters
in Planck cold cores is weaker, with lower values observed for both
parameters relative to other samples under our examination. The
cumulative distribution shapes of line widths in the Planck cold cores
closely resemble those of the dense cores found in regions of Cepheus,
in addition to Orion L1630 and L1641, with higher values compared to
Ophiuchus.
Description:
we used the Nanshan 26-m radio telescope to perform single-pointing
observations of NH3 (1,1) and (2,2) inversion transitions toward 672
Planck sources.
We conducted single-point observations of NH3 (1,1) and (2,2) lines
from March 2017 to August 2018 using the Nanshan 26-m telescope. A
22.0-24.2GHz dual polarization channel superheterodyne receiver was
employed, with the rest frequency centered at 23.708GHz to
simultaneously observe NH3 (1,1) (23.694GHz) and (2,2) (23.723GHz).
File tablea1.dat contains basic information of the observed sources.
File tablea2.dat contains observed parameters of the NH3 (1,1) and
NH3 (2,2) emission lines in the NH3 detected sources.
File tablea3.dat contains calculated parameters of the NH3 (1,1) and
(2,2) emission lines detected in the 73 cores.
File tablec1.dat contains parameters derived from the 12CO, 13CO, and
C18O (1-0) lines.
File tablec2.dat contains derived parameters of CO line.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 34 672 Basic information of the observed sources
tablea2.dat 89 249 Observed parameters of the NH3 (1,1) and
NH3 (2,2) emission lines in the NH3
detected sources
tablea3.dat 121 73 Contains calculated parameters of the NH3 (1,1)
and (2,2) emission lines detected in the
73 cores
tablec1.dat 112 195 Parameters derived from the 12CO, 13CO, and
C18O (1-0) lines
tablec2.dat 108 195 Derived parameters of CO line
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Galactic name (GLLL.ll+BB.bb)
15- 20 F6.2 deg GLON Galactic longitude of peak
22- 27 F6.2 deg GLAT Galactic latitude of peak
29- 34 F6.3 kpc Dist ? Heliocentric distance
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Galactic name (GLLL.ll+BB.bb)
14 A1 --- m_Name [ab] Multiplicity index on Name
16- 21 F6.2 km/s v(11) LSR velocity of the NH3(1,1)
inversion transition (23.694GHz)
23- 26 F4.2 km/s e_v(11) rms uncertainty on v(1,1)
28- 31 F4.2 km/s dv(11) NH3(1,1) linewidth
33- 36 F4.2 km/s e_dv(11) rms uncertainty on {DELTA}v(1,1)
38- 41 F4.2 --- tau(11) ? Optical depth of NH3(1,1) line (23.694GHz)
43- 46 F4.2 --- e_tau(11) ? rms uncertainty on tau(1,1)
48- 51 F4.2 K TMB(11) NH3(1,1) main beam brightness temperature
53- 56 F4.2 K e_TMB(11) rms uncertainty on TMB(1,1)
58- 63 F6.2 km/s v(22) ? LSR velocity of the NH3(2,2)
inversion transition (23.722GHz)
66- 69 F4.2 km/s e_v(22) ? rms uncertainty on v(2,2)
71- 74 F4.2 km/s dv(22) ? NH3(2,2) linewidth
76- 79 F4.2 km/s e_dv(22) ? rms uncertainty on dv(2,2)
81- 84 F4.2 K TMB(22) ? NH3(2,2) main beam brightness temperature
86- 89 F4.2 K e_TMB(22) ? rms uncertainty on TMB(2,2)
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Galactic name (GLLL.ll+BB.b)
14 A1 --- m_Name [ab] Multiplicity index on Name
16- 19 F4.2 K Tex Excitation temperature
21- 24 F4.2 K e_Tex rms uncertainty on Tex
26- 30 F5.2 K Trot Rotational temperature between the
NH3(1,1) and (2,2) inversion transition
32- 35 F4.2 K e_Trot rms uncertainty on Trot
37- 41 F5.2 K Tkin Kinematic temperature
43- 46 F4.2 K e_Tkin rms uncertainty on Kinematic temperature
48- 51 F4.2 [cm-2] NNH3 NH3 column density N(NH3)
53- 56 F4.2 [cm-2] e_NNH3 rms uncertainty on NNH3
58- 61 F4.2 km/s SigmaNT Nonthermal velocity dispersion SigmaNT
63- 67 F5.3 km/s e_SigmaNT rms uncertainty on SigmaNT
69- 72 F4.2 km/s SigmaTH Thermal velocity dispersion SigmaTH
74- 78 F5.3 km/s e_SigmaTH rms uncertainty on SigmaTH
80- 83 F4.2 km/s Cs Sound speed Cs
85- 89 F5.3 km/s e_Cs rms uncertainty on Cs
91- 94 F4.2 --- M Mach number
96- 99 F4.2 --- e_M rms uncertainty on M
101-104 F4.2 --- Rp Thermal-to-nonthermal pressure ratio
106-110 F5.3 --- e_Rp rms uncertainty on Rp
112-115 F4.2 10-7 chi ? NH3 abundance χ=N(NH3)/N(H2)
117-121 F5.3 10-7 e_chi ? rms uncertainty on chi
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Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Galactic name (GLLL.ll+BB.bb)
15- 20 F6.2 km/s v12CO LSR velocity of the 12CO(1-0) line
22- 25 F4.2 km/s e_v12CO rms uncertainty on v12CO
27- 31 F5.2 km/s dv12CO 12CO linewidth
33- 36 F4.2 km/s e_dv12CO rms uncertainty on dv12CO
38- 42 F5.2 K TMB12CO Main beam brightness temperature of the
12CO(1-0) transition
44- 47 F4.2 K e_TMB12CO rms uncertainty on TMB12CO
49- 54 F6.2 km/s v13CO LSR velocity of the 13CO(1-0) line
56- 59 F4.2 km/s e_v13CO rms uncertainty on v13CO
61- 64 F4.2 km/s dv13CO 13CO linewidth
66- 69 F4.2 km/s e_dv13CO rms uncertainty on dv13CO
71- 74 F4.2 K TMB13CO Main beam brightness temperature of the
13CO(1-0) transition
76- 79 F4.2 K e_TMB13CO rms uncertainty on TMB13CO
81- 86 F6.2 km/s vC18O ? LSR velocity of the C18O(1-0) line
88- 91 F4.2 km/s e_vC18O ? rms uncertainty on v13CO
93- 96 F4.2 km/s dvC18O ? C18O linewidth
98-101 F4.2 km/s e_dvC18O ? rms uncertainty on dvC18O
103-106 F4.2 K TMBC18O ? Main beam brightness temperature of the
C18O(1-0) transition
108-112 F5.3 K e_TMBC18O ? rms uncertainty on TMBC18O
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Byte-by-byte Description of file: tablec2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Galactic name (GLLL.ll+BB.bb)
15- 19 F5.2 K Tex(CO) Excitation temperature derived from CO lines
21- 24 F4.2 K e_Tex(CO) rms uncertainty on Tex(CO)
26- 29 F4.2 --- tau(13CO) ? Optical depth of 13CO
31- 34 F4.2 --- e_tau(13CO) ? rms uncertainty on tau(13CO)
36- 39 F4.2 --- tau(C18O) ? Optical depth of C18O
41- 44 F4.2 --- e_tau(C18O) ? rms uncertainty on tau(C18O)
46- 52 E7.1 [cm-2] N(13CO) ? 13CO column density N(13CO)
54- 60 E7.1 [cm-2] e_N(13CO) ? rms uncertainty on N(13CO)
62- 68 E7.1 [cm-2] N(C18O) ? 13CO column density N(C18O)
70- 76 E7.1 [cm-2] e_N(C18O) ? rms uncertainty on N(C18O)
78- 84 E7.1 [cm-2] NH2(13CO) ? Hydrogen column density derived
from 13CO column density
86- 92 E7.1 [cm-2] e_NH2(13CO) ? rms uncertainty on NH2(13CO)
94-100 E7.1 [cm-2] NH2(C18O) ? Hydrogen column density derived
from C18O column density
102-108 E7.1 [cm-2] e_NH2(C18O) ? rms uncertainty on NH2(C18O)
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Acknowledgements:
Dilda Berdikhan, dilda(at)xao.ac.cn
(End) Patricia Vannier [CDS] 05-Feb-2024