J/ApJS/257/39 NH3 isotope ratios of Galactic disk sources (Chen+, 2021)
Interstellar nitrogen isotope ratios: new NH3 data from the Galactic Center
out to the Perseus Arm.
Chen J.L., Zhang J.S., Henkel C., Yan Y.T., Yu H.Z., Qiu J.J., Tang X.D.,
Wang J., Liu W., Wang Y.X., Zheng Y.H., Zhao J.Y., Zou Y.P.
<Astrophys. J. Suppl. Ser., 257, 39 (2021)>
=2021ApJS..257...39C 2021ApJS..257...39C
ADC_Keywords: Molecular data; Interstellar medium; Radio lines; Milky Way
Keywords: Interstellar medium ; Galaxy abundances ;
Stellar nucleosynthesis ; Abundance ratios ; Stellar abundances ;
Radio astronomy ; Galaxy chemical evolution ; Interstellar molecules ;
Milky Way Galaxy
Abstract:
Our aim is to measure the interstellar 14N/15N ratio across the
Galaxy, to establish a standard data set on interstellar ammonia
isotope ratios, and to provide new constraints on the Galactic
chemical evolution. The (J,K)=(1,1), (2,2), and (3,3) lines of
14NH3 and 15NH3 were observed with the Shanghai Tianma 65m
radio telescope (TMRT) and the Effelsberg 100m telescope toward a
large sample of 210 sources. One hundred fourty-one of these sources
were detected by the TMRT in 14NH3. Eight of them were also
detected in 15NH3. For 10 of the 36 sources with strong NH3
emission, the Effelsberg 100m telescope successfully detected their
15NH3(1,1) lines, including 3 sources (G081.7522, W51D, and
Orion-KL) with detections by the TMRT telescope. Thus, a total of
15 sources are detected in both the 14NH3 and 15NH3 lines.
Line and physical parameters for these 15 sources are derived,
including optical depths, rotation and kinetic temperatures, and total
column densities. 14N/15N isotope ratios were determined from the
14NH3/15NH3 abundance ratios. The isotope ratios obtained from
both telescopes agree for a given source within the uncertainties, and
no dependence on heliocentric distance and kinetic temperature is
seen. 14N/15N ratios tend to increase with galactocentric
distance, confirming a radial nitrogen isotope gradient. This is
consistent with results from recent Galactic chemical model
calculations, including the impact of superasymptotic giant branch
stars and novae.
Description:
For our sample of 210 sources, we made observations of the
(J,K)=(1,1), (2,2), and (3,3) lines of 14NH3 and 15NH3
(23694.5MHz, 23722.6MHz, 23870.1MHz, 22624.9MHz, 22649.8MHz and
22789.4MHz, respectively), first with the Shanghai Tianma 65m radio
telescope (TMRT) in 2019 April, May, November, and December, with a
beam size of ∼50".
We also used the Effelsberg 100m telescope to observe the (J,K)=(1,1),
(2,2), and (3,3) lines of 14NH3 and 15NH3 toward 36 selected
sources with strong 14NH3 signals from previous TMRT observations
in 2019 December and 2020 January.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 102 108 Observational parameters of the (J,K)=(1,1), (2,2)
and (3,3) inversion lines of 14NH3 and
15NH3 obtained from Gaussian fits
(15 unique sources)
table4.dat 106 18 Observational parameters of NH3 measured with the
Shanghai Tianma 65m radio telescope (TMRT) and
the Effelsberg 100m telescope
table5.dat 113 23 Total 14NH3 and 15NH3 column densities with
and without opacity corrections and their ratios
table7.dat 74 1260 Our source list for 14NH3 and 15NH3
observations (195 unique sources)
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/699/1153 : Kinematic distances to GRS mol. clouds (Roman-Duval+, 2009)
J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010)
J/MNRAS/418/1689 : Red MSX water maser and ammonia emissions (Urquhart+, 2011)
J/MNRAS/430/1125 : RMS survey: NIR spectroscopy of massive YSOs (Cooper+, 2013)
J/ApJ/764/61 : H2O maser & NH3 survey of GLIMPSE EGOs (Cyganowski+, 2013)
J/ApJ/778/96 : Spitzer and NEWFIRM observations of NGC 6334 (Willis+, 2013)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/A+A/581/A48 : 1.3cm line survey toward Orion KL (Gong+, 2015)
J/MNRAS/453/645 : Molecular outflows distance-limited sample (Maud+, 2015)
J/ApJS/219/28 : C18O/C17O ratios in the Galactic center (Zhang+, 2015)
J/A+A/586/A50 : CMZ H2CO temperature maps (Ginsburg+, 2016)
J/A+A/609/A129 : HCN, HNC and DNC spectra of 27 sources (Colzi+, 2018)
J/MNRAS/478/3693 : N in Galactic high-mass star-forming cores (Colzi+, 2018)
J/ApJS/234/22 : SCUBA-2 Gal. Center compact source catalog (Parsons+, 2018)
J/MNRAS/473/1059 : Complete sample of Gal. clump properties (Urquhart+, 2018)
J/ApJ/885/131 : ∼200 high-mass SFR plx & pm with VLBI (Reid+, 2019)
J/ApJ/877/154 : H2CO TMRT obs. of Galactic molecular clouds (Yan+, 2019)
J/ApJ/899/145 : Sulfur isotopes in SFR with 12m ARO and 30m IRAM (Yu+, 2020)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Object identifier
12 A1 --- Tel Telescope code (1)
14- 15 I2 h RAh [0/20] Hour of Right Ascension (J2000)
17- 18 I2 min RAm Minute of Right Ascension (J2000)
20- 23 F4.1 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the Declination (J2000)
26- 27 I2 deg DEd Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 35 F4.1 arcsec DEs Arcsecond of Declination (J2000)
37- 39 I3 min Time [11/360] Total exposure time
41- 54 A14 --- Mol Molecule identifier
56- 61 F6.2 mK rms [6.38/135] Root Means Square noise (2)
63- 68 F6.2 K.km/s IntTmbdv [0.09/245]? Integrated intensity (3)
70- 73 F4.2 K.km/s e_IntTmbdv [0.01/4]? Uncertainty in IntTmbdv
75- 80 F6.2 km/s VLSR [-19.5/95.6]? Local Standard of Rest velocity
82- 85 F4.2 km/s e_VLSR [0.01/4]? Uncertainty in VLSR
87- 91 F5.2 km/s DeltaV [1/13]? Line width; FWHM
93- 96 F4.2 km/s e_DeltaV [0.01/9.3]? Uncertainty in DeltaV
98-102 F5.2 K Tmb [0.03/15.34]? Main beam brightness peak
temperature
--------------------------------------------------------------------------------
Note (1): Telescope as follows:
T = TMRT: the Shanghai Tianma radio telescope - 65m.
E = Effelsberg - 100m.
Note (2): For channel widths of 0.78km/s (TMRT) or 0.70km/s (Effelsberg).
Note (3): Covering all groups of hyperfine components from Gaussian fitting.
For three sources with blended components in the 14NH3 spectra,
their spectrum can not be fitted well by Gaussian fitting. Thus we
determined their integrated intensities by summing line intensities
over the entire velocity interval needed to cover the main and the
satellite features (Orion-KL: -45 to 51km/s; W51D: 13 to 105km/s
and G10.47: 20 to 113km/s) using the first moment by the "Print"
command in CLASS.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Object identifier
12- 21 A10 --- Tel Telescope
23- 26 F4.2 --- tau1_1 [0.22/2.56] Peak optical depth of the
(J,K)=(1,1) main group of HF components of
14NH3 from the intensity ratio method
28- 31 F4.2 --- etau11 [0.01/0.4] tau1_1 uncertainty
33- 36 F4.2 --- tau2_2 [0.12/5.52] Peak optical depth of the
(J,K)=(2,2) main group of HF components of
14NH3 from the intensity ratio method
38- 41 F4.2 --- etau22 [0.01/0.8] tau2_2 uncertainty
43- 46 F4.2 --- tau3_3 [0.11/8.56]? Peak optical depth of the
(J,K)=(3,3) main group of HF components of
14NH3 from the intensity ratio method
48- 51 F4.2 --- etau33 [0.01/1]? tau3_3 uncertainty
53- 56 F4.2 --- tau1_1HF [0.23/3.27]? Peak optical depth of the
(J,K)=(1,1) main group of HF components of
14NH3 from the HF fitting procedure
provided by CLASS
58- 62 F5.2 --- etau11HF [0.02/30.01]? tau1_1HF uncertainty
64- 67 F4.2 --- tau2_2HF [0.1/4.72]? Peak optical depth of the
(J,K)=(2,2) main group of HF components of
14NH3 from the HF fitting procedure
provided by CLASS
69- 72 F4.2 --- etau22HF [0.03/1.1]? tau2_2HF uncertainty
74- 77 F4.2 --- tau3_3HF [0.1/4.3]? Peak optical depth of the
(J,K)=(3,3) main group of HF components of
14NH3 from the HF fitting procedure
provided by CLASS
79- 82 F4.2 --- etau33HF [0.03/0.8]? tau3_3HF uncertainty
84- 85 I2 K Tir [14/36] Rotational temperature Trotir
from the intensity ratio method
87- 88 I2 K e_Tir [4/22] Tir uncertainty
90- 91 I2 K Trd [8/46] Trotrd from the rotation diagram
method
93- 94 I2 K e_Trd [3/16] Trd uncertainty
96- 97 I2 K Thf [10/27] Trothf from the improved HF
fitting method (1)
99- 100 I2 K e_Thf [1/17] Thf uncertainty
102- 103 I2 K Tk [11/40] Kinetic temperature calculated from
the empirical formula displayed in Appendix B
of Tafalla+ (2004A&A...416..191T 2004A&A...416..191T)
105- 106 I2 K e_Tk [1/22] Tk uncertainty
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Note (1): Trothf from the improved HF fitting method (see Section 3.2.2)
for 11 sources, that of NGC 6334 I from the RADEX calculation, and
that of the remaining three sources with blended spectral features
(G10.47, Orion-KL, and W51D) from the HFGR method (see details in
Section 3.2.2).
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Object identifier
12- 21 A10 --- Tel Telescope identifier
23- 29 E7.2 cm-2 Nt14NH3 [2.3e+14/1.2e+16]? 14NH3 column density
without opacity corrections
31- 37 E7.2 cm-2 Nt15NH3 [4.2e+12/3.2e+14] 15NH3 column density
without opacity corrections
39- 45 E7.2 cm-2 Ntc14NH3 [2.5e+14/3.1e+16]? 14NH3 column density
accounting for opacity effect
47- 53 E7.2 cm-2 Ntc15NH3 [4.6e+12/6e+14] 15NH3 column density
accounting for opacity effect (1)
55- 57 I3 --- Ratio [8/321] Ratio of the column densities,
14NH3/15NH3, neglecting opacity
corrections
59- 61 I3 --- e_Ratio [5/171] Ratio uncertainty
63- 65 I3 --- Ratioc [13/603] Opacity-corrected values of
14NH3/15NH3
67- 69 I3 --- e_Ratioc [6/213] Ratioc uncertainty
71- 74 F4.2 kpc Dist [0.21/8.4]? Heliocentric distance from the
parallax-based distance calculator
76- 79 F4.2 kpc e_Dist [0.11/1.3]? Dist uncertainty
81- 85 F5.2 kpc Rgc [0.31/10.3]? Galactocentric distance from
the heliocentric distance
87- 90 F4.2 kpc e_Rgc [0.11/2]? Rgc uncertainty
92- 97 A6 --- Class Source classification (2)
99-103 A5 --- r_Class References for the classification
from the literature (3)
105-113 A9 --- Notes Notes (4)
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Note (1): The corrected column density NtCorr(15NH3) was obtained with
the assumption of the same Trot as Trot(14NH3), which can be
derived taking into account the optical depth correction on 14NH3 in
the rotation diagram method.
Note (2): Classification as follows:
IRDC = infrared dark cloud (4 sources)
YSO = massive young stellar object (8 sources)
H II = associated with an HII region (2 sources)
UCH II = associated with an ultracompact HII region (1 source)
Note (3): Reference as follows:
Par18 = Parsons et al. (2018, J/ApJS/234/22)
Wyr96 = Wyrowski & Walmsley (1996A&A...314..265W 1996A&A...314..265W)
Urq18 = Urquhart et al. (2018, J/MNRAS/473/1059)
Coo13 = Cooper et al. (2013, J/MNRAS/430/1125)
God15 = Goddi et al. (2015A&A...573A.109G 2015A&A...573A.109G)
Urq11 = Urquhart et al. (2011, J/MNRAS/418/1689)
Wil13 = Willis et al. (2013, J/ApJ/778/96)
Mau15 = Maud et al. (2015, J/MNRAS/453/645)
Lis10 = Lis et al. (2010A&A...521L..26L 2010A&A...521L..26L)
Kim08 = Kim et al. (2008PASJ...60..991K 2008PASJ...60..991K)
Ryg10 = Rygl et al. (2010A&A...511A...2R 2010A&A...511A...2R)
Cut03 = Cutri et al. (2003, II/246)
Den84 = Dent et al. (1984MNRAS.210..173D 1984MNRAS.210..173D)
Note (4): Note as follows:
1 = the total column densities of 15NH3 were obtained from the
15NH3(1,1) line intensity, assuming the same Trot value for
15NH3 as for 14NH3.
2 = the total column densities of 15NH3 were obtained from the
15NH3(2,2) line intensity, assuming the same Trot value for
15NH3 as for 14NH3.
15NH3 = the total column densities of 15NH3 were obtained using the
Trot of 15NH3 from its 15NH3(1,1) and (2,2) line
intensities.
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- ID Object identifier
15- 18 A4 --- Tel Telescope
20- 21 I2 h RAh Hour of Right Ascension (J2000)
23- 24 I2 min RAm Minute of Right Ascension (J2000)
26- 31 F6.3 s RAs Second of Right Ascension (J2000)
34 A1 --- DE- Sign of the Declination (J2000)
35- 36 I2 deg DEd Degree of Declination (J2000)
38- 39 I2 arcmin DEm Arcminute of Declination (J2000)
41- 45 F5.2 arcsec DEs Arcsecond of Declination (J2000)
47- 51 F5.1 min Time [1.2/360] Total exposure time
53 A1 --- f_Mol [b] Indicates a line detection in Mol
55- 68 A14 --- Mol Molecule identifier
71- 74 I4 mK rms [6/7460] Root Means Square noise
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Feb-2022