J/ApJS/268/56 Obs. of Gal. interstellar ratio 18O/17O. II. (Zou+, 2023)
A systematic observational study on Galactic interstellar ratio 18O/17O.
II. C18O and C17O J=2-1 data analysis.
Zou Y.P., Zhang J.S., Henkel C., Romano D., Liu W., Zheng Y.H., Yan Y.T.,
Chen J.L., Wang Y.X., Zhao J.Y.
<Astrophys. J. Suppl. Ser., 268, 56 (2023)>
=2023ApJS..268...56Z 2023ApJS..268...56Z
ADC_Keywords: Carbon monoxide; Molecular clouds; Milky Way; Interstellar medium
Keywords: Interstellar molecules ; Radio source counts ; Isotopic abundances ;
Galaxy chemical evolution
Abstract:
To investigate the relative amount of ejecta from high-mass versus
intermediate-mass stars and to trace the chemical evolution of the
Galaxy, we have performed a systematic study of Galactic interstellar
18O/17O ratios toward a sample of 421 molecular clouds with
IRAM-30m and the 10m Submillimeter Telescope, covering a
galactocentric distance range of ∼1-22kpc. The results presented in
this paper are based on the J=2-1 transition and encompass 364 sources
showing both C18O and C17O detections. The previously suggested
18O/17O gradient is confirmed. For the 41 sources detected with
both facilities, good agreement is obtained. A correlation of the
18O/17O ratios with heliocentric distance is not found, indicating
that beam dilution and linear beam sizes are not relevant. For the
subsample of IRAM 30m high-mass star-forming regions with accurate
parallax distances, an unweighted fit gives
18O/17O=(0.12±0.02)RGC+(2.38±0.13) with a correlation
coefficient of R=0.67. While the slope is consistent with our J=1-0
measurement, the ratios are systematically lower. This should be
caused by larger optical depths of C18O 2-1 lines with respect to
the corresponding 1-0 transitions, which is supported by RADEX
calculations and the fact that C18O/C17O is positively correlated with
13CO/C18O. When we consider that optical depth effects with
C18O(J=2-1) typically reach an optical depth of ∼0.5, the corrected
18O/17O ratios from the J=1-0 and J=2-1 lines are consistent. A
good numerical fit to the data is provided by the MWG-12 model, which
includes both rotating stars and novae.
Description:
Our observations of the C18O and C17O J=2-1 lines were carried out
from 2017 January 11 until January 17, using the IRAM 30m at the Pico
Veleta Observatory (Granada, Spain). The center frequencies were set
at 219.560354 and 224.714187GHz for the C18O and C17O lines,
respectively.
With the IRAM 30m, we observed 103 sources of our sample. The
observational parameters are summarized in Table 1.
Our Submillimeter Telescope (SMT) 10m (on Mount Graham, Arizona, USA)
observations of J=2-1 lines were performed remotely in 2016 May and
June, 2018 January and November, 2019 December, 2020 June, July, and
November, and in 2021 January and February with a beam size of ∼29".
Table 1 presents the observational parameters of the SMT 10m results
for the sample of 380 sources, including the 62 sources that were
observed by both the IRAM 30m and the SMT 10m telescopes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 125 966 Observational parameters and 18O/17O
isotope ratios toward 420 molecular clouds
table2.dat 122 164 A comparison of IRAM 30m and SMT 10m results for
the 41 common sources with C18O and C17O detections
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See also:
J/A+AS/80/149 : IRAS Sources behind the Solar circle (Wouterloot+ 1989)
J/A+A/430/549 : C18O/C17O near rho Oph (Wouterloot+, 2005)
J/ApJ/724/748 : Galactic anticenter PNe and oxygen abundance (Henry+, 2010)
J/ApJ/741/110 : The BGPS. VII. Massive star-forming regions (Dunham+, 2011)
J/MNRAS/418/1689 : Red MSX water maser and ammonia emissions (Urquhart+, 2011)
J/A+A/544/A146 : ATLASGAL cold high-mass clumps with NH3 (Wienen+, 2012)
J/ApJ/764/61 : H2O maser & NH3 survey of GLIMPSE EGOs (Cyganowski+, 2013)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/ApJS/219/28 : C18O/C17O ratios in the Galactic center (Zhang+, 2015)
J/ApJ/822/59 : BGPS. XIV. Molecular cloud clumps GBT obs. (Svoboda+, 2016)
J/ApJS/237/13 : Models & yields of massive stars (Limongi+, 2018)
J/MNRAS/490/2779 : Dust clumps assoc. with methanol masers (Billington+, 2019)
J/ApJ/885/131 : High-mass SFR plx & proper motion with VLBI (Reid+, 2019)
J/ApJ/877/154 : H2CO TMRT obs. of Galactic molecular clouds (Yan+, 2019)
J/A+A/642/A222 : CS isotopes towards Galactic centre clouds (Humire+, 2020)
J/ApJ/899/145 : Sulfur isotopes in SFR with 12m ARO and 30m IRAM (Yu+, 2020)
J/ApJS/249/6 : Galactic interstellar ratio 18O/17O. I. (Zhang+, 2020)
J/ApJS/257/39 : NH3 isotope ratios of Galactic disk sources (Chen+, 2021)
J/A+A/649/A21 : ATLASGAL deuteration of ammonia (Wienen+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Source Name (GBBB.bb+LL.ll or WB89 NNNA)
14 A1 --- m_Name Component on source name for G123.06-06.30
16- 17 I2 h RAh Hour of Right Ascension (J2000)
19- 20 I2 min RAm Minute of Right Ascension (J2000)
22- 25 F4.1 s RAs Second of Right Ascension (J2000)
27- 27 A1 --- DE- Sign of the Declination (J2000)
28- 29 I2 deg DEd Degree of Declination (J2000)
31- 32 I2 arcmin DEm Arcminute of Declination (J2000)
34- 38 F5.2 arcsec DEs Arcsecond of Declination (J2000)
40- 44 F5.2 kpc RGC [0.3/22.6]? Galactocentric distance
46- 50 F5.2 kpc Dist [0.1/20.5]? Heliocentric distance
52- 55 A4 --- Tel Telescope used ("IRAM" or "SMT")
57- 60 A4 --- Line Line ("C18O" or "C17O")
62- 64 I3 mK rms [9/750]? Root-mean-square value; in units of Tmb
66- 73 F8.3 km/s Vpeak [-102/121]? Velocity of the peak Tmb
75- 79 F5.3 km/s e_Vpeak [0/0.5]? Uncertainty in Vpeak
81- 86 F6.3 km/s FWHM [0.6/18.8]? FWHM
88- 92 F5.3 km/s e_FWHM [0.001/1.1]? Uncertainty in FWHM
94-100 F7.3 K.km/s Tmbdv [0.06/181]? Integrated line intensity
102-106 F5.3 K.km/s e_Tmbdv [0.008/2.7]? Uncertainty in Tmbdv
108-113 F6.3 K Tpeak [0.03/21.7]? Antenna temperature at Tmb peak
115-119 F5.3 --- Rcorr [1.2/9.6]? Frequency-corrected abundance ratio
121-125 F5.3 --- e_Rcorr [0.008/2]? Uncertainty in Rcorr
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Source Name (GBBB.bb+LL.ll or WB89 NNN)
14 A1 --- m_Name Component on source name for G123.06-06.30
16- 17 I2 h RAh Hour of Right Ascension (J2000)
19- 20 I2 min RAm Minute of Right Ascension (J2000)
22- 25 F4.1 s RAs Second of Right Ascension (J2000)
27- 28 I2 deg DEd Degree of Declination (J2000)
30- 31 I2 arcmin DEm Arcminute of Declination (J2000)
33- 37 F5.2 arcsec DEs Arcsecond of Declination (J2000)
39- 43 F5.2 kpc RGC [6.3/13.7] Galactocentric distance
45- 49 F5.2 kpc Dist [0.6/10.8] Heliocentric distance
51- 54 A4 --- Tel Telescope used ("IRAM" or "SMT")
56- 59 A4 --- Line Line ("C18O" or "C17O")
61- 63 I3 mK rms [22/186]? Root-mean-square value;
in units of Tmb
65- 71 F7.3 km/s Vpeak [-73/67.1]? Velocity of the peak Tmb
73- 77 F5.3 km/s e_Vpeak [0/0.5]? Uncertainty in Vpeak
79- 83 F5.3 km/s FWHM [0.9/9.3]? FWHM
85- 89 F5.3 km/s e_FWHM [0.001/0.8]? Uncertainty in FWHM
91- 97 F7.3 K.km/s Tmbdv [0.8/161.1]? Integrated line intensity
99-103 F5.3 K.km/s e_Tmbdv [0.008/1.3]? Uncertainty in Tmbdv
105-110 F6.3 K Tpeak [0.15/20.4]? Antenna temperature at Tmb peak
112-116 F5.3 --- Rcorr [2.6/4.4]? Frequency-corrected abundance ratio
118-122 F5.3 --- e_Rcorr [0.018/1]? Uncertainty in Rcorr
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History:
From electronic version of the journal
References:
Zhang et al. Paper I. 2020ApJS..249....6Z 2020ApJS..249....6Z Cat. J/ApJS/249/6
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Jan-2024