DCO/sup +//HCO/sup +/ abundance ratio and the electron density in cool interstellar clouds

Journal Article · Thu Jun 15 04:00:00 EDT 1978 · Astrophys. J., Lett.; (United States)

DOI:https://doi.org/10.1086/182712· OSTI ID:6827210

Watson, W D; Snyder, L E

The J=1-0 transiton of H/sup 13/CO/sup +/ has been detected in L134 at one-third the level (integrated antenna temperatures) of D/sup 12/CO/sup +/. Scaling of the DCO/sup +/-to-H/sup 13/CO/sup +/ abundance ratio and high-resolution studies of line profiles also presented here then provide more reliable information than previously available about the abundances of DCO/sup +/ and H/sup 12/CO/sup +/ in the representative dark cloud L134. These data imply that low relative abundances for electrons, CO, and N/sub 2/ do in fact occur, though our more firm upper limits are somewhat higher than those derived by certain previous investigators. We find (e)/(H/sub 2/)< or approx. =4 x 10/sup -8/ and (CO)/(H/sub 2/), (N/sub 2/),/(Hd2)< or approx. =1< or approx. =10/sup -5/. Since the H/sup 13/CO/sup +/ intensity is also one-seventh the level of H/sup 12/CO/sup +/ and the actual /sup 13/C//sup 12/C abundance ratio is quite unlikely to be so large, emission by the more abundant species is apparently reduced by optical depth effects. This casts doubt on the general validity of the premise that the DCO/sup +/-to-H/sup 12/CO/sup +/ abundance ratio in cool interstellar clouds can be derived by assuming that it is essentially the same as that which would be derived in the optically thin case.

• Research Organization: University of Illinois-Urbana
• OSTI ID: 6827210
• Journal Information: Astrophys. J., Lett.; (United States), Journal Name: Astrophys. J., Lett.; (United States) Vol. 222:3; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics &amp; Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CARBON
CHEMISTRY
COSMOCHEMISTRY
DEUTERIUM
ELECTRON DENSITY
ELEMENTS
ENERGY-LEVEL TRANSITIONS
HYDROGEN ISOTOPES
INTERSTELLAR MAGNETIC FIELDS
INTERSTELLAR SPACE
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MAGNETIC FIELDS
MOLECULES
NONMETALS
NUCLEI
ODD-ODD NUCLEI
SPACE
STABLE ISOTOPES