J/ApJ/753/50 6.7GHz methanol masers. I. NH3 lines (Pandian+, 2012)
Physical conditions around 6.7 GHz methanol masers.
I. Ammonia.
Pandian J.D., Wyrowski F., Menten K.M.
<Astrophys. J., 753, 50 (2012)>
=2012ApJ...753...50P 2012ApJ...753...50P
ADC_Keywords: Masers ; Radio lines
Keywords: masers; stars: formation
Abstract:
Methanol masers at 6.7GHz are known to be tracers of high-mass star
formation in our Galaxy. In this paper, we study the large-scale
physical conditions in the star-forming clumps/cores associated with
6.7GHz methanol masers using observations of the (1,1), (2,2), and
(3,3) inversion transitions of ammonia with the Effelsberg telescope.
The gas kinetic temperature is found to be higher than in infrared
dark clouds, highlighting the relatively evolved nature of the maser
sources. Other than a weak correlation between maser luminosity and
the ammonia line width, we do not find any differences between low-
and high-luminosity methanol masers.
Description:
The observations were carried out between 2009 April 30 and May 7
using the Effelsberg 100m telescope. The receiver was tuned to a
frequency of 23.78GHz allowing simultaneous observation of the (1,1),
(2,2), and (3,3) NH3 inversion transitions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 96 79 Properties of NH3 lines toward the AMGPS sources
(Arecibo Methanol Maser Galactic Plane Survey)
table2.dat 64 61 *Physical parameters determined from the NH3
observations
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Note on table2.dat: Only sources with at least 4σ detections of at least
two NH3 transitions are shown in this table.
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See also:
J/MNRAS/431/1752 : ATLASGAL 6.7GHz methanol masers (Urquhart+, 2013)
J/ApJS/195/14 : The Bolocam Galactic Plane Survey. V. (Schlingman+, 2011)
J/A+A/486/191 : Distances towards 6.7GHz methanol masers (Pandian+, 2008)
J/ApJ/669/435 : AMGPS. Paper II. (Pandian+, 2007)
J/ApJ/656/255 : Arecibo methanol Maser Galactic Plane Survey (Pandian+, 2007)
J/AZh/84/579 : Catalog of Class I methanol masers (Val'tts+, 2007)
J/MNRAS/377/571 : GLIMPSE 6.7GHz masers non-detections (Ellingsen+, 2007)
J/A+A/432/737 : General Cat. of 6.7GHz Methanol Masers (Pestalozzi+, 2005)
J/A+A/403/1095 : 6.7GHz methanol masers survey of low-mass YSO (Minier+, 2003)
J/other/ChJAA/3.49 : Velocity & distance of methanol maser sources (Xu+, 2003)
J/A+AS/143/269 : 6.7GHz methanol maser emission survey (Szymczak+, 2000)
J/A+AS/134/115 : Medicina 6.7GHz methanol masers survey (Slysh+ 1999)
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 AMGPS source designation (GLL.ll+B.bb) (G1)
12 A1 --- m_Name [ab] Mutiplicity flag on Name (G2)
14- 18 F5.1 km/s Vlsr [-44.4/94.6]? LSR velocity (1)
20 A1 --- l_TMB11 Limit flag on TMB11 (3σ upper limit)
22- 25 F4.2 K TMB11 [0.09/2.9] NH3(1,1) main beam brightness
temperature
27- 30 F4.2 K e_TMB11 [0.02/0.09]? TMB11 uncertainty (2)
32- 35 F4.2 km/s dV11 [0.7/4.4]? NH3(1,1) FWHM (G3)
37- 40 F4.2 km/s e_dV11 [0.01/0.8]? dV11 uncertainty
42- 45 F4.2 --- tau11 [0.2/4.5]? NH3(1,1) optical depth (3)
47- 50 F4.2 --- e_tau11 [0.06/1.7]? tau11 uncertainty
52 A1 --- l_TMB22 Limit flag on TMB22 (3σ upper limit)
54- 57 F4.2 K TMB22 [0.07/1.8] NH3(2,2) main beam brightness
temperature
59- 62 F4.2 K e_TMB22 [0.02/0.1]? TMB22 uncertainty (2)
64- 67 F4.2 km/s dV22 [1.2/5.2]? NH3(2,2) FWHM (G3)
69- 72 F4.2 km/s e_dV22 [0.04/0.9]? dV22 uncertainty
74 A1 --- l_TMB33 Limit flag on TMB33 (3σ upper limit)
76- 79 F4.2 K TMB33 [0.07/3]? NH3(3,3) main beam brightness
temperature
81 A1 --- f_TMB33 [a] Blended line (4)
83- 86 F4.2 K e_TMB33 [0.03/0.09]? TMB33 uncertainty (2)
88- 91 F4.2 km/s dV33 [1.2/5.6]? NH3(3,3) FWHM (G3)
93- 96 F4.2 km/s e_dV33 [0.06/0.6]? dV33 uncertainty
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Note (1): No uncertainties are shown for the line velocities since they are well
below 0.1km/s.
Note (2): Note that the uncertainties in TMB only include the formal fitting
errors and do not include the uncertainty in flux calibration.
Note (3): Sources for which no τ(1,1,m) is listed had their (1,1) spectra
fitted using Gaussians due to the line being too weak.
Note (4):
a = No reliable fit possible due to blending from two closely separated
velocity components.
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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 AMGPS source designation (GLL.ll+B.bb) (G1)
12 A1 --- m_Name [ab] Multiplicity flag on Name (G2)
14- 16 F3.1 K Tex11 [3/8] Excitation temperature of NH3(1,1)
18 A1 --- f_Tex11 [a] Assumed value of Tex11 (5)
20- 22 F3.1 K e_Tex11 [0.1/2.3] Tex11 uncertainty (6)
24- 27 F4.1 K TR21 [12/32] Rotation temperature from (2,2)
and (1,1) lines
29- 31 F3.1 K e_TR21 [0.9/9.1] TR21 uncertainty (6)
33- 36 F4.1 K Tk [14/68] Kinetic temperature
38- 41 F4.1 K E_Tk [1.5/94] Tk positive error (6)
43- 46 F4.1 K e_Tk [1.5/32] Tk negative error (6)
48- 51 F4.1 K TR31 [17/56]? Rotation temperature from
(3,3) and (1,1) lines
53- 56 F4.1 K e_TR31 [0.7/19]? TR31 uncertainty (6)
58- 60 F3.1 10+15cm-2 N(NH3) [0.9/8] Total NH3 column density
62- 64 F3.1 10+15cm-2 e_N(NH3) [0.2/3] N(NH3) uncertainty (6)
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Note (5):
a = Tex assumed to be 4.1±0.9K since the optical depth of the (1,1) main
hyperfine component is not constrained.
Note (6): The uncertainties include contributions from the flux calibration.
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Global notes:
Note (G1): Arecibo Methanol Maser Galactic Plane Survey, Pandian et al., 2007,
Cat. J/ApJ/669/435 (See also Cat. J/ApJ/656/255);
<[PGD2007] GLL.ll+B.bb> in Simbad.
Note (G2): Four sources (in table 1) could be fitted using two velocity
components in both (1,1) and (2,2) transitions, and the two
components are distinguished by the suffix "a" and "b".
Note (G3): FWHM = Full Width at Half Maximum, measures the line width
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 12-Feb-2014