Detection of 15NH2D in dense cores: A new tool for measuring the 14N/15N ratio in the cold ISM

Abstract

Ammonia is one of the best tracers of cold dense cores. It is also a minor constituent of interstellar ices and, as such, one of the important nitrogen reservoirs in the protosolar nebula, together with the gas phase nitrogen, in the form of N2 and N. An important diagnostic of the various nitrogen sources and reservoirs of nitrogen in the Solar System is the 14N/15N isotopic ratio. While good data exist for the Solar System, corresponding measurements in the interstellar medium are scarce and of low quality. Following the successful detection of the singly, doubly, and triply deuterated isotopologues of ammonia, we have searched for 15NH2D in dense cores, as a new tool for investigating the 14N/15N ratio in dense molecular gas. With the IRAM-30m telescope, we have obtained deep integrations of the ortho 15NH2D (1(1,1)-1(0,1)) line at 86.4 GHz, simultaneously with the corresponding ortho NH2D line at 85.9 GHz. o-15NH2D is detected in Barnard-1b, NGC1333-DCO+, and L1689N, while we obtained upper limits towards LDN1544 and NGC1333-IRAS4A, and a tentative detection towards L134N(S). The 14N/15N abundance ratio in NH2D ranges between 350 and 850, similar to the protosolar value of ~ 424, and likely higher than the terrestrial ratio of 270.

References in corpus (7)

• Observing the gas temperature drop in the high-density nucleus of L 1544
• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• Depletion and low gas temperature in the L183 prestellar core : the N2H+ - N2D+ tool
• Discovery of Fulminic Acid, HCNO, in Dark Clouds
• Large excess of heavy nitrogen in both hydrogen cyanide and cyanogen from comet 17P/Holmes
• Nitrogen superfractionation in dense cloud cores
• The distribution of ND2H in LDN1689N

Cited by in corpus (36)

• Our astrochemical heritage
• Interstellar Hydrides
• Isotopic fractionation of carbon, deuterium and nitrogen : a full chemical study
• Isotope selective photodissociation of N2 by the interstellar radiation field and cosmic rays
• Nitrogen isotopic ratios in Barnard 1: a consistent study of the N2H+, NH3, CN, HCN and HNC isotopologues
• 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
• Nitrogen Isotopic Fractionation in Interstellar Ammonia
• Nitrogen fractionation in high-mass star-forming cores across the Galaxy
• Spectral line survey of the ultracompact HII region Mon R2
• The CN/C15 N isotopic ratio towards dark clouds
• Observations of nitrogen isotope fractionation in deeply embedded protostars
• Nitrogen and hydrogen fractionation in high-mass star forming cores from observations of HCN and HNC
• A theoretical room-temperature line list for 15NH3
• Revised Models of Interstellar Nitrogen Isotopic Fractionation
• ${}^{14}$N/${}^{15}$N ratio measurements in prestellar cores with N${}_2$H${}^{+}$: new evidence of ${}^{15}$N-antifractionation
• Depletion of heavy nitrogen in the cold gas of star-forming regions
• First measurements of 15N fractionation in N2H+ toward high-mass star forming cores
• Chemical nitrogen fractionation in dense molecular clouds
• The nitrogen isotopic ratio of HC3N towards the L1544 prestellar core
• First measurement of the 14N/15N ratio in the analogue of the Sun progenitor OMC-2 FIR4
• N${}_2$H${}^{+}$ and N${}^{15}$NH${}^{+}$ towards the prestellar core 16293E in L1689N
• The rotational spectrum of ${}^{15}$ND. Isotopic-independent Dunham-type analysis of the imidogen radical
• Precise observations of the 12C/13C ratios of HC3N in the low-mass star-forming region L1527
• 15N Fractionation in Infrared-Dark Cloud Cores
• First interferometric study of enhanced N-fractionation in N${}_2$H${}^{+}$: the high-mass star-forming region IRAS 05358+3543
• Detection of N15NH+ in L1544
• Depletion and fractionation of nitrogen in collapsing cores
• Deuterium and ${}^{15}$N fractionation in N${}_2$H${}^{+}$ during the formation of a Sun-like star
• Nitrogen fractionation in ammonia and its insights on nitrogen chemistry
• Accurate rotational rest frequencies for ammonium ion isotopologues
• Depletion of 15N in the center of L1544: Early transition from atomic to molecular nitrogen?
• ExoMol line lists -- LX. Molecular line list for the ammonia isotopologue ${}^{15}$NH${}_3$
• Interstellar Nitrogen Isotope Ratios: New NH3 Data from the Galactic Center out to the Perseus Arm
• Amides from the carbonaceous asteroid (162173) Ryugu: nanoscale spectral and isotopic characterizations