Chlorine in the Galactic Interstellar Medium: Revised f-Values with the Far Ultraviolet Spectroscopic Explorer and the Space Telescope Imaging Spectrograph
Abstract
Cl I is the atomic species most directly coupled to molecular hydrogen due to its chemistry. Its weakest lines are thereby probably the best tracer of optically thick H2 components in diffuse clouds. We report on the empirical determination of the oscillator strengths for four Cl I absorption lines predicted to be weak and often detected toward moderately reddened sight lines observed with the Far Ultraviolet Spectroscopic Explorer (FUSE). We compared our oscillator strength estimates with the oscillator strength calculations listed in Morton. We find that our empirical oscillator strength values for the Cl I 1004, 1079, 1090, and 1094 Å lines differ from the theoretical predictions by factors of ~3.1, 1.2, 2.4, and 0.42, respectively. We briefly discuss the value of Cl I as tracer of molecular gas for our star sample.
Based on observations made with the NASA/ESA Hubble Space Telescope (HST), obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2006
- DOI:
- 10.1086/508772
- arXiv:
- arXiv:astro-ph/0609132
- Bibcode:
- 2006ApJ...650L.115S
- Keywords:
-
- ISM: Abundances;
- ISM: Atoms;
- ISM: Clouds;
- ISM: General;
- Astrophysics
- E-Print:
- 12 pages, 3 figures, accepted for publication in ApJL