2013A&A...560A...3D


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.17CET17:39:06

2013A&A...560A...3D - Astronomy and Astrophysics, volume 560A, 3-3 (2013/12-1)

Nitrogen isotopic ratios in Barnard 1: a consistent study of the N2H+, NH3, CN, HCN, and HNC isotopologues.

DANIEL F., GERIN M., ROUEFF E., CERNICHARO J., MARCELINO N., LIQUE F., LIS D.C., TEYSSIER D., BIVER N. and BOCKELEE-MORVAN D.

Abstract (from CDS):

The 15N isotopologue abundance ratio measured today in different bodies of the solar system is thought to be connected to 15N-fractionation effects that would have occurred in the protosolar nebula. The present study aims at putting constraints on the degree of 15N-fractionation that occurs during the prestellar phase, through observations of D, 13C, and 15N-substituted isotopologues towards B1b. Molecules both from the nitrogen hydride family, i.e. N2H+, and NH3, and from the nitrile family, i.e. HCN, HNC, and CN, are considered in the analysis. As a first step, we modelled the continuum emission in order to derive the physical structure of the cloud, i.e. gas temperature and H2 density. These parameters were subsequently used as input in a non-local radiative transfer model to infer the radial abundance profiles of the various molecules. Our modelling shows that all the molecules are affected by depletion onto dust grains in the region that encompasses the B1-bS and B1-bN cores. While high levels of deuterium fractionation are derived, we conclude that no fractionation occurs in the case of the nitrogen chemistry. Independently of the chemical family, the molecular abundances are consistent with 14N/15N∼300, a value representative of the elemental atomic abundances of the parental gas. The inefficiency of the 15N-fractionation effects in the B1b region can be linked to the relatively high gas temperature ∼17 K, which is representative of the innermost part of the cloud. Since this region shows signs of depletion onto dust grains, we cannot exclude the possibility that the molecules were previously enriched in 15N, earlier in the B1b history and that such an enrichment could have been incorporated into the ice mantles. It is thus necessary to repeat this kind of study in colder sources to test such a possibility.

Abstract Copyright:

Journal keyword(s): ISM: abundances - ISM: molecules - ISM: individual objects: Barnard 1 - line: formation - astrochemistry - techniques: spectroscopic

Simbad objects: 13

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Number of rows : 13

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 1333 SFR 03 28 55 +31 22.2   10.9       ~ 1182 1
2 Barnard 1 MoC 03 33 16.3 +31 07 51           ~ 247 0
3 [HKM99] B1-b cor 03 33 20.32 +31 07 21.5           ~ 150 0
4 [HRF2005] 3 PoC 03 33 21.3 +31 07 27           ~ 54 0
5 [KJD2006] SMM J033335+31075 PoC 03 33 21.3 +31 07 28           ~ 66 0
6 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1010 0
7 LDN 1498 DNe 04 11.0 +24 58           ~ 241 0
8 NAME [BM89] L1521E DNe 04 29 21.0 +26 14 19           ~ 82 1
9 NAME Taurus Dark Cloud SFR 04 41.0 +25 52           ~ 3322 0
10 LDN 1544 DNe 05 04 16.6 +25 10 48           ~ 655 0
11 [PCW91] Ced 110 IRS 10 Y*O 11 06 33.38 -77 23 34.6           ~ 57 1
12 LDN 183 MoC 15 54 12.2 -02 49 42           ~ 674 1
13 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 463 0

    Equat.    Gal    SGal    Ecl

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2019.11.17-17:39:06

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