Universität zu Köln

Colzi, L., Fontani, F., Rivilla, V. M., Sanchez-Monge, A., Testi, L., Beltran, M. T. and Caselli, P. (2018). Nitrogen fractionation in high-mass star-forming cores across the Galaxy. Mon. Not. Roy. Astron. Soc., 478 (3). S. 3693 - 3721. OXFORD: OXFORD UNIV PRESS. ISSN 1365-2966

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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 (HNC)-C-13, (HCN)-N-15, (HCN)-C-13 and (HCN)-N-15, and derived the N-14/N-15 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 N-14/N-15 ratios are distributed around the Proto-Solar Nebula value with a lower limit near the TA value (similar to 272). We have also derived the N-14/N-15 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 similar to 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.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Colzi, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fontani, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Rivilla, V. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sanchez-Monge, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Testi, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Beltran, M. T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Caselli, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-178290
DOI:	10.1093/mnras/sty1027
Journal or Publication Title:	Mon. Not. Roy. Astron. Soc.
Volume:	478
Number:	3
Page Range:	S. 3693 - 3721
Date:	2018
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1365-2966
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PROTOSTELLAR CANDIDATES; CHEMICAL EVOLUTION; NUCLEOSYNTHESIS; HCN; TRANSITIONS; SPECTRUM; CARBON; CH3CN; N-15; HNC Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17829