Bibcode
Frost, R. L.; Beckman, J. E.; Watt, G. D.; White, G. J.; Phillips, J. P.
Bibliographical reference
IN: Submillimetre wave astronomy (A84-29251 12-89). Cambridge and New York, Cambridge University Press, 1982, p. 253-259.
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1982
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Refereed citations
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Description
The abundance ratio of D:H in the interstellar medium can be derived
either more directly from the UV absorption measurements of HD and H2 in
the spectra of early-type stars, or less directly from millimeter-wave
emission in the rotational lines of a variety of molecules. The latter
method is applicable over a much larger portion of the galaxy, but is
subject to the uncertainty inherent in chemical fractionation. It is
shown here how the basic assumptions of temperature distribution and
geometry within a single source can cause the derived ratio HDO:H2O to
vary between 0.05 and 0.0025, a comparable range to that found with
three different molecules DCN:HCN, DNC:HNC, and DCO(+):HCO(+) in the
same source. This result should lead to caution in the interpretation of
such abundance ratios and of their gradients within the galaxy.