Detection in the Interstellar Medium of the Weak [Mg II] Transition at 1398.8 Å
Snow, Theodore P.; Destree, Joshua D.; Williamson, Karen E.
United States
Abstract
High- and medium-resolution ultraviolet spectra from the Space Telescope Imaging Spectrograph and the Goddard High Resolution Spectrograph were used to search for the weak electric quadrupole transitions of [Mg II] near 1398.8 Å. This forbidden doublet was detected in eight sight lines. We calculate an empirical f-value of (1.29 ± 0.13) × 10-5 from all detections and discuss prospects of using this weak line in future studies of translucent interstellar clouds and in damped Lyα systems.
Based on observations made with the NASA/ESA Hubble Space Telescope, 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.