ULTRAVIOLET MEASUREMENTS OF INTERSTELLAR C{sub 2}
We analyzed archival spectra acquired with the Hubble Space Telescope for a study of interstellar C{sub 2}. Absorption from the electronic transitions, D {sup 1}{Sigma}{sup +}{sub u} - X {sup 1}{Sigma}{sup +}{sub g} (0,0) as well as F {sup 1}{Pi}{sub u} - X {sup 1}{Sigma}{sup +}{sub g} (0,0) and (1,0), was the focus of the study. Our profile syntheses revealed that the lines of the F - X bands were broadened as a result of a perturbation involving the upper levels. Further evidence for the perturbation came from anomalies in line strength and position for the F - X (0,0) band. The perturbation likely arises from a combination of triplet-singlet interactions involving spin-orbit mixing between {sup 3}{Pi}{sub u} states and F {sup 1}{Pi}{sub u} and an avoided crossing between the {sup 3}{Pi}{sub u} states. Tunneling through a potential barrier caused by the 3 and 4 {sup 1}{Pi}{sub u} states and spin-orbit mixing with other close-lying triplet states of ungerade symmetry are less likely. Except for the broadening, lines in the F - X (1,0) band appear free from anomalies and can be used to study interstellar C{sub 2}; new results for 10 sight lines are presented.
- OSTI ID:
- 22140035
- Journal Information:
- Astrophysical Journal, Vol. 761, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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