Detection of N15NH+ in L1544

Abstract

Excess levels of 15N isotopes which have been detected in primitive solar system materials are explained as a remnant of interstellar chemistry which took place in regions of the protosolar nebula. Chemical models of nitrogen fractionation in cold clouds predict an enhancement in the gas-phase abundance of 15N-bearing molecules, thus we have searched for 15N variants of the N2H+ ion in L1544, which is one of the best candidate sources for detection owing to its low central core temperature and high CO depletion. With the IRAM 30m telescope we have obtained deep integrations of the N2H+(1-0) line at 91.2 GHz. The N2H+(1-0) line has been detected toward the dust emission peak of L1544. The 14N/15N abundance ratio in N2H+ resulted 446+/-71, very close to the protosolar value of ~450, higher than the terrestrial ratio of ~270, and significantly lower than the lower limit in L1544 found by Gerin et al. (2009, ApJ, 570, L101) in the same object using ammonia isotopologues.

Accepted for publication in Astronomy and Astrophysics

References in corpus (4)

• Cold Dark Clouds: The Initial Conditions for Star Formation
• Observing the gas temperature drop in the high-density nucleus of L 1544
• Nitrogen superfractionation in dense cloud cores
• Detection of 15NH2D in dense cores: A new tool for measuring the 14N/15N ratio in the cold ISM

Cited by in corpus (11)

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• The 15N-enrichment in dark clouds and Solar System objects
• Isotopic Anomalies in Primitive Solar System Matter: Spin-state Dependent Fractionation of Nitrogen and Deuterium in Interstellar Clouds
• Detection of (15)NNH+ in L1544: non-LTE modelling of dyazenilium hyperfine line emission and accurate (14)N/(15)N values
• The CN/C15 N isotopic ratio towards dark clouds
• Observations of nitrogen isotope fractionation in deeply embedded protostars
• Ion-molecule reactions involving HCO${}^{+}$ and N${}_2$H${}^{+}$: Isotopologue equilibria from new theoretical calculations and consequences for interstellar isotope fractionation
• 15N Fractionation in Infrared-Dark Cloud Cores
• Depletion of 15N in the center of L1544: Early transition from atomic to molecular nitrogen?