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J/A+A/609/A129      HCN, HNC and DNC spectra of 27 sources        (Colzi+, 2018)

Nitrogen and hydrogen fractionation in high-mass star forming cores from observations of HCN and HNC. Colzi L., Fontani F., Caselli P., Ceccarelli C., Hily-Blant P., Bizzocchi L. <Astron. Astrophys. 609, A129 (2018)> =2018A&A...609A.129C (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Radio lines Keywords: radio lines: ISM - ISM: molecules - ISM: abundances Abstract: The ratio between the two stable isotopes of nitrogen, 14N and 15N, is well measured in the terrestrial atmosphere (∼272), and for the pre-solar nebula (∼441, deduced from the solar wind). Interestingly, some pristine solar system materials show enrichments in 15N with respect to the pre-solar nebula value. However, it is not yet clear if and how these enrichments are linked to the past chemical history because we have only a limited number of measurements in dense star-forming regions. In this respect, dense cores, which are believed to be the precursors of clusters and also contain intermediate- and high-mass stars, are important targets because the solar system was probably born within a rich stellar cluster, and such clusters are formed in high-mass star-forming regions. The number of observations in such high-mass dense cores has remained limited so far. In this work, we show the results of IRAM-30m observations of the J=1-0 rotational transition of the molecules HCN and HNC and their 15N-bearing counterparts towards 27 intermediate- and high-mass dense cores that are divided almost equally into three evolutionary categories: high-mass starless cores, high-mass protostellar objects, and ultra-compact Hii regions. We have also observed the DNC(2-1) rotational transition in order to search for a relation between the isotopic ratios D/H and 14N/15N. We derive average 14N/15N ratios of 359±16 in HCN and of 438±21 in HNC, with a dispersion of about 150-200. We find no trend of the 14 N/15 N ratio with evolutionary stage. This result agrees with what has been found for N2H+ and its isotopologues in the same sources, although the 14N/15N ratios from N2H+ show a higher dispersion than in HCN/HNC, and on average, their uncertainties are larger as well. Moreover, we have found no correlation between D/H and 14N/15N in HNC. These findings indicate that (1) the chemical evolution does not seem to play a role in the fractionation of nitrogen, and that (2) the fractionation of hydrogen and nitrogen in these objects is not related. Description: We performed observations of the J=1-0 rotational transition of H15NC, HN13C, HC15N and H13CN towards the 27 sources observed by Fontani et al. (2015ApJ...808L..46F) from 6 to 9 June, 2015, using the 3mm receiver of the IRAM-30m telescope. We simultaneously observed the J=2-1 transition of DNC with the 2mm receiver. IRAM-30m Telescope, 1mm and 3mm receivers, fast Fourier transform spectrometers: FTS50 File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file sources.dat 142 27 *Total column densities (beam-averaged), of H15NC, HN13C, DNC (table 3) and HC15N and H13CN(1-0) transitions (table 4) dnc/* 89 27 DNC spectra h13cn/* 89 27 H13CN spectra h15nc/* 89 27 H15NC spectra hc15n/* 89 27 HC15N spectra hn13c/* 89 27 HN13C spectra
Note on sources.dat: Total column densities computed as explained in Sect. 3.
Byte-by-byte Description of file: sources.dat
Bytes Format Units Label Explanations
1- 5 A5 --- Type Type (HMPO, HMSC or UCHII) 7- 19 A13 --- Source Source name 20 A1 --- n_Source [w] Note on Source (1) 21- 22 A2 --- l_N(H15NC) [≤ ] Limit flag on N(H15NC) 23- 25 I3 10+10cm-2 N(H15NC) Total H15NC column density (beam-averaged) 27- 28 I2 10+10cm-2 e_N(H15NC) ? rms uncertainty on N(H15NC) (2) 29 A1 --- n_N(H15NC) [ut] Note on N(H15NC) (1) 31- 32 I2 10+10cm-2 DN1 ?=- Error on N(H15NC) without considering the calibration error 34- 38 F5.1 10+11cm-2 N(HN13C) Total HN13C column density (beam-averaged) 40- 43 F4.1 10+11cm-2 e_N(HN13C) rms uncertainty on N(HN13C) (2) 45- 47 F3.1 10+11cm-2 DN2 Error on N(HN13C) without considering the calibration error 49- 52 F4.1 10+11cm-2 N(DNC) Total DNC column density (beam-averaged) 54- 56 F3.1 10+11cm-2 e_N(DNC) rms uncertainty on N(DNC) (2) 58- 59 A2 --- l_HNC/H15NC [≥ ] Limit flag on HNC/H15NC 60- 62 I3 --- HNC/H15NC HNC/H15NC isotopic ratio (3) 64- 66 I3 --- e_HNC/H15NC ? rms uncertainty on HNC/H15NC (2) 68- 71 I4 --- HNC/DNC HNC/DNC isotopic ratio (4) 73- 75 I3 --- e_HNC/DNC rms uncertainty on HNC/DNC (2) 77- 82 E6.2 --- DNC/HNC DNC/HNC isotopic ratio 84- 89 E6.2 --- e_DNC/HNC rms uncertainty on DNC/HNC (2) 91- 92 A2 --- l_N(HC15N) [≤ ] Limit flag on N(HC15N) 93- 96 I4 10+10cm-2 N(HC15N) Total N(HC15N) column density (beam-averaged) 98-100 I3 10+10cm-2 e_N(HC15N) ? rms uncertainty on N(HC15N) 101 A1 --- n_N(HC15N) [ut] Note on N(HC15N) (1) 103-104 I2 10+10cm-2 DN3 ?=- Error on N(HC15N) without considering the calibration error 106-108 I3 10+11cm-2 N(H13CN) Total H13CN column density (beam-averaged) 110-111 I2 10+11cm-2 e_N(H13CN) rms uncertainty on N(H13CN) (2) 113-115 F3.1 10+11cm-2 DN4 Error on N(H13CN) without considering the calibration error 117-118 A2 --- l_HCN/HC15N [≥ ] Limit flag on HCN/HC15N 119-121 I3 --- HCN/HC15N HCN/HC15N isotopic ratio (3) 123-125 I3 --- e_HCN/HC15N ? rms uncertainty on HCN/HC15N (2) 127-128 I2 K Tk Kinetic temperature of the clump (5) 129 A1 --- n_Tk [*] Note on Tk (6) 131-142 A12 --- FName Name used in the spectra files (7)
Note (1): Flag as follows: w = "warm" HMSC u = upper limit t = tentative detection Note (2): Uncertainties in the column densities and in the isotope ratios have been computed as explained in Sect. 3.1 and 3.2. Note (3): it has been multiplied by 12C/13C as described in Section (3.1). Note (4): it has been multiplied by 12C/13C and by the correction of the different beams 3.09. Note (5): kinetic temperatures of the clumps derived from Fontani et al. (2015ApJ...808L..46F): for the sources without a derivation of Tk, the mean value for that evolutionary stage was taken (for the HMSCs the average was done without the "warm" ones, i.e those with a Tk<20K). Note (6): * for average value for the specific evolutionary stage Note (7): The spectra files are named : FName-dnc.spt in dnc subdirectory, FName-h13cn.spt in h13cn subdirectory, FName-h15cn.spt in 15cnn subdirectory, FName-hc15n.spt in hc15n subdirectory, FName-hn13c.spt in hn13c subdirectory.
Byte-by-byte Description of file: dnc/* h13cn/* h15nc/* hc15n/* hn13c/*
Bytes Format Units Label Explanations
1- 17 E17.13 km/s Vlsr LSR velocity 19- 29 E11.5 K Tmb Beam brightness temperature 32- 41 E10.5 --- Tmbf1 ? Tmb computed in the fit 44- 53 E10.5 --- Tmbf2 ? Tmb computed in the fit 56- 65 E10.5 --- Vlsr2 ? LSR velocity for the possible second component 68- 77 E10.5 --- Tmbs1 ? Beam brightness temperature for the possible second component 80- 89 E10.5 --- Tmbs2 ? Tmb computed in the fit for the possible second component
Acknowledgements: Laura Colzi, colzi(at)arcetri.astro.it
(End) Laura Colzi [Univ. Florence, Italy], Patricia Vannier [CDS] 20-Nov-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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