Interstellar iron and silicon depletions in translucent sight lines

Adam Miller*, J. T. Lauroesch, Ulysses J. Sofia, Stefan I.B. Cartledge, David M. Meyer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


We report interstellar Fe II and Si II column densities toward six translucent sight lines (AV ≳ 1) observed with the Space Telescope Imaging Spectrograph (STIS). The abundances were determined from the absorption of Si II] at 2335 Å, and several weak Fe transitions including the first reported detections of the λ2234 line. We derive an empirical f-value for the Fe II λ2234 transition of log (fλ) = -1.54 ± 0.05. The observed sight lines sample a variety of extinction characteristics as indicated by their RV values, which range from 2.6 to 5.8. The dust-phase abundances of both Si and Fe are positively correlated with the small-grain population (effective radii smaller than a few hundred μm) toward the targets. The physical conditions along the sight lines suggest that this relationship may be due to differences in the survival of small particles in some interstellar environments. The chemical composition of the small grains could either resemble dust mantles or be silicate-rich.

Original languageEnglish (US)
Pages (from-to)441-446
Number of pages6
JournalAstrophysical Journal
Issue number1 I
StatePublished - Apr 10 2007


  • Dust, extinction
  • ISM: abundances

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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