J/ApJ/777/157 90GHz obs. of high-mass star-forming regions (Hoq+, 2013)
Chemical evolution in high-mass star-forming regions:
results from the MALT90 survey.
Hoq S., Jackson J.M., Foster J.B., Sanhueza P., Guzman A., Whitaker J.S.,
Claysmith C., Rathborne J.M., Vasyunina T., Vasyunin A.
<Astrophys. J., 777, 157 (2013)>
=2013ApJ...777..157H 2013ApJ...777..157H
ADC_Keywords: Radio lines ; H II regions ; Interstellar medium ;
Millimetric/submm sources ; Galactic plane ; Surveys
Keywords: astrochemistry; ISM: abundances; ISM: clouds; ISM: molecules;
stars: formation
Abstract:
The chemical changes of high-mass star-forming regions provide a
potential method for classifying their evolutionary stages and,
ultimately, ages. In this study, we search for correlations between
molecular abundances and the evolutionary stages of dense molecular
clumps associated with high-mass star formation. We use the molecular
line maps from Year 1 of the Millimetre Astronomy Legacy Team 90GHz
(MALT90) Survey. The survey mapped several hundred individual
star-forming clumps chosen from the ATLASGAL survey to span the
complete range of evolution, from prestellar to protostellar to H II
regions. The evolutionary stage of each clump is classified using the
Spitzer GLIMPSE/MIPSGAL mid-IR surveys. Where possible, we determine
the dust temperatures and H2 column densities for each clump from
Herschel/Hi-GAL continuum data. From MALT90 data, we measure the
integrated intensities of the N2H+, HCO+, HCN and HNC(1-0)
lines, and derive the column densities and abundances of N2H+ and
HCO+. The Herschel dust temperatures increase as a function of the
IR-based Spitzer evolutionary classification scheme, with the youngest
clumps being the coldest, which gives confidence that this
classification method provides a reliable way to assign evolutionary
stages to clumps. Both N2H+ and HCO+ abundances increase as a
function of evolutionary stage, whereas the N2H+(1-0) to
HCO+(1-0) integrated intensity ratios show no discernable trend. The
HCN(1-0) to HNC(1-0) integrated intensity ratios show marginal
evidence of an increase as the clumps evolve.
Description:
Observations were taken with the 22m single dish Australia Telescope
National Facility (ATNF) Mopra Telescope as part of Year 1 of the
Millimetre Astronomy Legacy Team 90GHz (MALT90) Survey. Target sources
were chosen from the APEX Telescope Large Area Survey of the Galaxy
(ATLASGAL) Catalog (Contreras et al. 2013, J/A+A/549/A45; superseded
by J/A+A/568/A41) of compact 870um continuum sources. Observations
were taken from 2010 June to September of 499 high-mass star-forming
regions. The Mopra beamwidth is 38" at 86GHz. Of the 499 sources
observed, only 333 were confidently classified into one of the three
evolutionnary stages (quiescent, protostellar, and HII/PDR regions).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 333 MALT90 clump parameters
table4.dat 133 1332 Gaussian fit parameters for the 333 regions
table5.dat 125 333 Derived molecular properties
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See also:
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
J/A+A/565/A75 : ATLASGAL. Dust condensations (Csengeri+, 2014)
J/A+A/557/A94 : SiO and HCO+ massive molecular outflows (Sanchez-Monge+, 2013)
J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330<l<21 (Contreras+, 2013)
J/ApJ/756/60 : A 3mm line survey in 37 IR dark clouds (Sanhueza+, 2012)
J/ApJS/197/25 : MALT90 pilot survey (Foster+, 2011)
J/A+A/527/A88 : Chemistry in infrared dark clouds (Vasyunina+, 2011)
J/AJ/136/2391 : GLIMPSE Extended Green Objects catalog (Cyganowski+, 2008)
J/ApJ/641/389 : Millimetric observations of IRDC cores (Rathborne+, 2006)
J/ApJ/639/227 : MSX IRDC candidate catalog (Simon+, 2006)
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
http://malt90.bu.edu/ : MALT90 home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Source identifier (GLLL.lll+BB.bbb)
17- 18 I2 h RAh [12/18] Hour of Right Ascension (J2000)
20- 21 I2 min RAm Minute of Right Ascension (J2000)
23- 26 F4.1 s RAs Second of Right Ascension (J2000)
28 A1 --- DE- [-] Sign of the Declination (J2000)
29- 30 I2 deg DEd [19/63] Degree of Declination (J2000)
32- 33 I2 arcmin DEm Arcminute of Declination (J2000)
35- 38 F4.1 arcsec DEs Arcsecond of Declination (J2000)
40- 51 A12 --- Class Spitzer Classification (H II; Protostellar;
Quiescent or PDR=photodissociation region)
53- 56 F4.1 K T [9/42]? Temperature
58- 60 F3.1 K e_T [0.9/6]? Lower uncertainty in T
62- 64 F3.1 K E_T [1.4/9]? Upper uncertainty in T
66- 70 F5.1 10+22/cm2 NH2 [0/100.2]? The H2 column density
72- 76 F5.2 10+22/cm2 e_NH2 [0.01/25.1]? Uncertainty in NH2
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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- 21 A21 --- Mol Molecular line identifier
23- 37 A15 --- Name Source identifier
39- 42 F4.2 K Trms ? Root-mean-square temperature (noise in T*A)
44- 47 F4.2 K T*A [0.08/6.1]? Antenna temperature
49- 52 F4.2 K e_T*A [0.01/0.2]? Uncertainty in T*A
54- 57 F4.2 K.km/s sigma [0.04/0.4]? 1σ uncertainty of
integrated intensity
59- 63 F5.2 K.km/s Int [0.1/11.8]? Integrated Intensity
over ±1km/s of T*A
65- 69 F5.2 km/s DelV [0.7/19.7]? Line width ΔV
71- 74 F4.2 km/s e_DelV [0.02/2.2]? Uncertainty in DelV
76- 82 F7.2 km/s Vlsr [-128.3/193]? Local Standard of Rest velocity (1)
84- 88 F5.2 km/s e_Vlsr [-0/79.4]? Uncertainty in Vlsr
90-133 A44 --- Det Detection category (2)
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Note (1): These values are based on the fits to the average spectra in the
central circular area of diameter 38" of each map. The consensus
velocities of the MALT90 sample will be released in a forthcoming
publication (Whitaker et al. 2013, in prep), which may differ from
the present values by ∼1km/s.
Note (2):
Broadended = The lines are too broad to produce reliable fits and so this
source is not included in the analysis of the molecular
parameters. Broadended sources are mostly located near the
galactic center.
Upper Limit = A non detection, but a ΔV of 2.0km/s was assumed and the
brightness temperatures of the lines were set equal to 3 times
the rms of the spectrum to produce upper limits. Therefore, no
uncertainties are listed for these values.
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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- 15 A15 --- Name Source identifier
17- 19 F3.1 --- OD-N2H+ [0/3]? The N2H+ optical depth
21- 23 F3.1 --- e_OD-N2H+ [0.1/3]? Uncertainty in OD-N2H+
25- 29 F5.1 --- OD-HCO+ [3/218]? The HCO+ optical depth
31- 35 F5.1 --- e_OD-HCO+ [0.4/331]? Uncertainty in OD-HCO+
37- 41 F5.1 10+12/cm2 CD-N2H+ [1/158]? The N2H+ column density
43- 46 F4.1 10+12/cm2 e_CD-N2H+ [0.6/29]? Uncertainty in CD-N2H+
48- 51 F4.1 10+14/cm2 CD-HCO+ [0.4/36]? The HCO+ column density
53- 56 F4.1 10+14/cm2 e_CD-HCO+ [0.1/59]? Uncertainty in CD-HCO+
58- 62 F5.1 10-10 A-N2H+ [0/168]? The N2H+ abundance
64- 67 F4.1 10-10 e_A-N2H+ [0.1/79]? Uncertainty in A-N2H+
69- 73 F5.1 10-9 A-HCO+ [0.2/197]? The HCO+ abundance
75- 78 F4.1 10-9 e_A-HCO+ [0.1/92]? Uncertainty in A-HCO+
80- 98 A19 --- Dt-N2H+ The N2H+ detection type (1)
100-125 A26 --- Dt-HCO+ The HCO+ detection type (1)
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Note (1): The meanings of the categories are:
N2H+ Detection (5/3 HF) = Detection (hyperfine
T123-012≥(5/3)*T112-012);
N2H+ Edge = Edge of Spectral Window;
HCO+ Self-Ab = HCO+ (1-0) Self-Absorbed;
HCO+ Self-Ab (T13≥T12) = HCO+ (1-0) Self-Absorbed,
Peak of H13CO+ (1-0) ≥ Peak of HCO+ (1-0);
HCO+ Detection (T13≥T12) = HCO+ (1-0) Detected, Peak of
H13CO+ (1-0) ≥ Peak of HCO+ (1-0);
HCO+ Two Limits = HCO+ (1-0) Self-Absorbed,
H13CO+ (1-0) Upper Limit;
UL = Upper Limit;
Multiple Vel. Comp. = Multiple Velocity Components in Spectrum.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Apr-2015