Nitrogen fractionation in high-mass star-forming cores across the Galaxy
Date Issued
2018
Author(s)
Colzi, L.
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Sánchez-Monge, A.
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Caselli, P.
Abstract
The fractionation of nitrogen (N) in star-forming regions is a poorly understood process. To put more stringent observational constraints on the N-fractionation, we have observed with the IRAM-30-m telescope a large sample of 66 cores in massive star-forming regions. We targeted the (1-0) rotational transition of HN13C, HC15N, H13CN and HC15N, and derived the 14N/15N ratio for both HCN and HNC. We have completed this sample with that already observed by Colzi et al., and thus analysed a total sample of 87 sources. The 14N/15N ratios are distributed around the Proto-Solar Nebula value with a lower limit near the TA value (∼272). We have also derived the 14N/15N ratio as a function of the Galactocentric distance and deduced a linear trend based on unprecedented statistics. The Galactocentric dependences that we have found are consistent, in the slope, with past works but we have found a new local 14N/15N value of ∼400, i.e. closer to the Prosolar Nebula value. A second analysis was done, and a parabolic Galactocentric trend was found. Comparison with Galactic chemical evolution models shows that the slope until 8 kpc is consistent with the linear analysis, while the flattening trend above 8 kpc is well reproduced by the parabolic analysis.
Volume
478
Issue
3
Start page
3693
Issn Identifier
0035-8711
Ads BibCode
2018MNRAS.478.3693C
Rights
open.access
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