SIMBAD references

1998A&A...337..246L - Astronomy and Astrophysics, volume 337, 246-252 (1998/9-1)

Interstellar isotope ratios from mm-wave molecular absorption spectra.


Abstract (from CDS):

We have measured galactic λ3mm absorption spectra of HCO+, HCN, HNC, and CS toward compact extragalactic continuum sources in order to derive the isotopic abundance ratios 12C/13C, 14N/15N, 16O/18O, and 32S/34S in local diffuse clouds. For carbon, our data confirm recent results for the local ISM: we find 12C/13C=59±2. For nitrogen, we find 14N/15N=237(-21,+27) consistent with the Solar value of 270, but substantially smaller than the values inferred from HCN emission in dense clouds. For sulfur we find 32S/34S ≃19±8 consistent with the Solar value of 23. We also find one striking individual anomaly: toward 3C111 (B0415+379), H12CN/H13^CN=170±50 in one kinematic component. We attribute this to the fractionation of 13C into 13CO which may be so great that HCN is starved for 13C.

Abstract Copyright:

Journal keyword(s): ISM: abundances - ISM: clouds - ISM: molecules - ISM: structure - radio lines: interstellar

Simbad objects: 14

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