Relative abundances of /sup 28/Si, /sup 29/Si, and /sup 30/Si in the interstellar medium
Millimeter-wave observations of the J = 2..-->..1 (v = 0) rotational transition of /sup 28/SiO and the isotopically substituted species /sup 29/SiO and /sup 30/SiO have been made toward four dense molecular clouds. Additional observations of the J = 3..-->..2 (v = 0) transition of /sup 28/SiO toward the same clouds were also made. The results are utilized to derive relative isotope abundances in the interstellar medium. It is shown that (/sup 29/Si//sup 28/Si) and (/sup 30/Si//sup 28/Si) are significantly larger than the terrestrial values, whereas the terrestrial and interstellar (/sup 30/Si//sup 29/Si) abundance ratios are comparable provided all lines are optically thin. No evidence for variation of isotope abundance with galactic radius is found.
- Research Organization:
- Bell Telephone Laboratories, Holmdel, New Jersey
- OSTI ID:
- 6535692
- Journal Information:
- Astrophys. J.; (United States), Vol. 242:3
- Country of Publication:
- United States
- Language:
- English
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ENERGY SPECTRA
ENERGY-LEVEL TRANSITIONS
ISOTOPE RATIO
MICROWAVE RADIATION
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640105* - Astrophysics & Cosmology- Galaxies