Atomic Physics with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. III. Oscillator Strengths for Neutral Carbon

Abstract

High quality spectra of interstellar absorption from C I toward β¹ Sco, ρ Oph A, and χ Oph were obtained with the Goddard High Resolution Spectrograph on HST. Many weak lines were detected within the observed wavelength intervals: 1150-1200 Å for β¹ Sco and 1250-1290 Å for ρ Oph A and χ Oph. Curve-of-growth analyses were performed in order to extract accurate column densities and Doppler parameters from lines with precise laboratory-based f-values. These column densities and b-values were used to obtain a self-consistent set of f-values for all the observed C I lines. A particularly important constraint was the need to reproduce data for more than one line of sight. For about 50% of the lines, the derived f-values differ appreciably from the values quoted by Morton.

Based on observations obtained with the NASA/ESA Hubble Space Telescope through the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.