J/A+A/544/A146 ATLASGAL cold high-mass clumps with NH3 (Wienen+, 2012)
Ammonia from cold high-mass clumps discovered in the inner Galactic disk by
the ATLASGAL survey.
Wienen M., Wyrowski F., Schuller F., Menten K.M., Walmsley C.M.,
Bronfman L., Motte F.
<Astron. Astrophys. 544, A146 (2012)>
=2012A&A...544A.146W 2012A&A...544A.146W
ADC_Keywords: Galactic plane; Interstellar medium; Radial velocities;
Spectra, millimetric/submm; Surveys
Keywords: surveys - submillimeter: general - radio lines: ISM - ISM: molecules -
ISM: kinematics and dynamics - stars: formation
Abstract:
The APEX Telescope Large Area Survey: The Galaxy (ATLASGAL) is an
unbiased continuum survey of the inner Galactic disk at 870 micron. It
covers ±60° in Galactic longitude and aims to find all massive
clumps at various stages of high-mass star formation in the inner
Galaxy, particularly the earliest evolutionary phases.
We aim to determine properties such as the gas kinetic temperature and
dynamics of new massive cold clumps found by ATLASGAL. Most
importantly, we derived their kinematical distances from the measured
line velocities.
We observed the ammonia (J,K)=(1,1) to (3,3) inversion transitions
toward 862 clumps of a flux-limited sample of submm clumps detected by
ATLASGAL and extracted 13CO(1-0) spectra from the Galactic Ring
Survey (GRS). We determined distances for a subsample located at the
tangential points (71 sources) and for 277 clumps whose near/far
distance ambiguity is resolved.
Most ATLASGAL clumps are cold with rotational temperatures from 10-30K
with a median of 17K. They have a wide range of NH3 linewidths
(1-7km/s with 1.9km/s as median, which by far exceeds the thermal
linewidth, as well as a broad distribution of high column densities
from 1014 to 1016cm-2 (median of 2x1015cm-2) with an NH3
abundance in the range of 5 to 30x10-8. ATLASGAL sources are
massive, >100M☉, and a fraction of clumps with a broad linewidth
is in virial equilibrium. We found an enhancement of clumps at
Galactocentric radii of 4.5 and 6kpc. The comparison of the NH3
lines as high-density probes with the GRS 13CO emission as
low-density envelope tracer yields broader linewidths for 13CO than
for NH3. The small differences in derived clump velocities between
NH3 (representing dense core material) and 13CO (representing more
diffuse molecular cloud gas) suggests that the cores are essentially
at rest relative to the surrounding giant molecular cloud.
The high detection rate (87%) confirms ammonia as an excellent probe
of the molecular content of the massive, cold clumps revealed by
ATLASGAL. A clear trend of increasing rotational temperatures and
linewidths with evolutionary stage is seen for source samples ranging
from 24 micron dark clumps to clumps with embedded HII regions. The
survey provides the largest ammonia sample of high-mass star forming
clumps and thus presents an important repository for the
characterization of statistical properties of the clumps and the
selection of subsamples for detailed, high-resolution follow-up
studies.
Description:
The NH3(1,1) to (3,3) inversion transitions of a flux-limited sample
from the ATLASGAL survey, which reaches a Galactic longitude of
±60° and latitude of ±1.5°, were observed with the
Effelsberg 100-m telescope. The ammonia (1,1) to (3,3) spectra are
shown and NH3 line parameters are derived for 752 ATLASGAL sources.
For each clump equatorial coordinates, the optical depths of the
NH3(1,1) line as well as the LSR velocities, linewidths and main
beam brightness temperatures of the ammonia (1,1) to (3,3) inversion
transitions are given. In addition, the rotational temperature,
kinetic temperature, the column density and beam filling factor are
derived from the NH3 lines. The H2 column density, NH3
abundance, 870 micron dust continuum flux as well as near and far
kinematic distances are given. In addition, 13CO(1-0) spectra of a
subsample were extracted from the Galactic Ring Survey and the 13CO
velocity, linewidth and main beam brightness temperature are shown.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 752 Source positions and NH3(1,1) line parameters
table2.dat 85 752 NH3(2,2) and (3,3) line parameters
table3.dat 47 752 Parameters derived from the NH3(1,1) to (3,3)
inversion transitions
table4.dat 50 752 Parameters obtained from the NH3 lines and from
the 870 micron dust continuum
table5.dat 57 513 Line parameters derived from the 13CO(1-0)
transition for 513 ATLASGAL sources emitting 13CO
sp/* . 2247 FITS spectra for NH3 lines (1,1), (2,2) and (3,3)
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See also:
J/A+A/540/A113 : Starless clumps in ATLASGAL (Tackenberg+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name ATLASGAL source name (GLLL.ll+B.bb)
12 A1 --- m_Name [ab] Multiplicity index on Name
14- 15 I2 h RAh Right Ascension J2000 (hours)
17- 18 I2 min RAm Right Ascension J2000 (minutes)
20- 26 F7.4 s RAs Right Ascension J2000 (seconds)
28 A1 --- DE- Declination J2000 (sign)
29- 30 I2 deg DEd Declination J2000 (degrees)
32- 33 I2 arcmin DEm Declination J2000 (minutes)
35- 40 F6.3 arcsec DEs Declination J2000 (seconds)
42- 45 F4.2 --- tau(1,1) Optical depth of NH3(1,1) line (23.694GHz)
47- 50 F4.2 --- e_tau(1,1) rms uncertainty on tau(1,1)
52- 57 F6.2 km/s v(1,1) LSR velocity of the NH3(1,1) inversion
transition
59- 62 F4.2 km/s e_v(1,1) rms uncertainty on v(1,1)
64- 67 F4.2 km/s dv(1,1) NH3(1,1) linewidth
69- 72 F4.2 km/s e_dv(1,1) rms uncertainty on dv(1,1)
74- 77 F4.2 K TMB(1,1) NH3(1,1) main beam brightness temperature
79- 82 F4.2 K e_TMB(1,1) rms uncertainty on TMB(1,1)
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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- 11 A11 --- Name ATLASGAL source name (GLLL.ll+B.bb)
12 A1 --- m_Name [ab] Multiplicity index on Name
14- 19 F6.2 km/s v(2,2) ?=- LSR velocity of the NH3(2,2) inversion
transition (23.722GHz)
21- 24 F4.2 km/s e_v(2,2) ? rms uncertainty on v(2,2)
26- 31 F6.2 km/s dv(2,2) ?=- NH3(2,2) linewidth
34- 37 F4.2 km/s e_dv(2,2) ? rms uncertainty on dv(2,2)
39 A1 --- l_TMB(2,2) Limit flag on TMB(2,2)
40- 43 F4.2 K TMB(2,2) ?=- NH3(2,2) main beam brightness temperature
45- 48 F4.2 K e_TMB(2,2) ? rms uncertainty on TMB(2,2)
50- 55 F6.2 km/s v(3,3) ?=- LSR velocity of the (3,3) line (23.870GHz)
57- 60 F4.2 km/s e_v(3,3) ? rms uncertainty on v(3,3)
62- 68 F7.3 km/s dv(3,3) ?=- NH3(3,3) linewidth
70- 74 F5.3 km/s e_dv(3,3) ? rms uncertainty on dv(3,3)
76 A1 --- l_TMB(3,3) Limit flag on TMB(3,3)
77- 80 F4.2 K TMB(3,3) ?=- NH3(3,3) main beam brightness temperature
82- 85 F4.2 K e_TMB(3,3) ? rms uncertainty on TMB(3,3)
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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- 11 A11 --- Name ATLASGAL source name (GLLL.ll+B.bb)
12 A1 --- m_Name [ab] Multiplicity index on Name
14- 18 F5.2 K Trot ?=- Rotational temperature between the
NH3(1,1) and (2,2) inversion transition
20- 24 F5.2 K e_Trot ?=- rms uncertainty on Trot
26- 30 F5.2 K Tkin ?=- Kinetic temperature
32- 36 F5.2 K e_Tkin ?=- rms uncertainty on Tkin
38- 42 F5.2 [cm-2] log(NNH3) ?=- NH3 column density log(N(NH3))
44- 47 F4.2 [cm-2] e_log(NNH3) ?=- rms uncertainty on log(NNH3)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name ATLASGAL source name (GLLL.ll+B.bb)
12 A1 --- m_Name [ab] Multiplicity index on Name
14- 17 F4.2 --- eta ?=- Beam filling factor η
19- 24 F6.2 10+22cm-2 NH2 ?=- H2 column density N(NH2)
26- 30 F5.2 10-7 chi ?=- NH3 abundance χ=N(NH3)/N(H2)
32- 36 F5.2 Jy S870 ?=- 870 micron dust continuum flux
integrated over 40arcsec
38- 42 F5.2 kpc Dnear ?=- Near kinematic distance
43 A1 --- n_Dnear [*] * for source with known distance
45- 49 F5.2 kpc Dfar ?=- Far kinematic distance
50 A1 --- n_Dfar [*] * for source with known distance
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name ATLASGAL source name (GLLL.ll+B.bb)
12 A1 --- m_Name [ab] Multiplicity index on Name
14- 21 F8.3 km/s v13CO ?=-999 LSR velocity of the 13CO(1-0) line
23- 27 F5.3 km/s e_v13CO ?=9.99 rms uncertainty on v13CO
29- 36 F8.3 km/s dv13CO ?=-999 13CO linewidth
38- 43 F6.3 km/s e_dv13CO ?=9.99 rms uncertainty on dv13CO
44- 51 F8.3 K TMB13CO ?=-999 Main beam brightness temperature of the
13CO(1-0) transition (110.201GHz)
52- 57 F6.3 K e_TMB13CO ?=9.99 rms uncertainty on TMB13CO
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Acknowledgements:
Marion Wienen, mwienen(at)mpifr-bonn.mpg.de
References:
Schuller et al., 2009arXiv0903.1369S 2009arXiv0903.1369S, ATLASGAL-The APEX telescope large area
survey of the galaxy at 870 micron
Jackson et al., 2006ApJS..163..145J 2006ApJS..163..145J, The Boston University-Five College
Radio Astronomy Observatory Galactic Ring Survey
(End) Patricia Vannier [CDS] 30-Jul-2012