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Deuterium in the Local Interstellar Medium: Its Cosmological Significance

  • Jeffrey L. Linsky
  • Athanassios Diplas
  • Blair Savage
  • Catherine Andrulis
  • Alex Brown
Part of the Astrophysics and Space Science Library book series (ASSL, volume 187)

Abstract

We report on our ongoing program to measure the deuterium/hydrogen (D/H) ratio and interstellar gas properties along many lines of sight through the local interstellar medium using the HST Goddard High-Resolution Spectrograph. For the line of sight towards Capella (12.5 pc) we had previously found D/H=1.65(+0.07, -0.18)×l0-5, T=7,000 K, and turbulent velocity 1.66 km s-1. These quantities were determined by modeling the interstellar hydrogen and deuterium Lyman alpha lines and the resonance lines of Fe II and Mg II against the background stellar emission-line profiles. We now report on our preliminary analysis of these spectral lines for the line of sight toward Procyon (3.5 pc). We find that D/H=1.40 ± 0.05 × 10-5 (±3σ photometric random errors only), which is lower than but perhaps consistent with the value of D/H derived for the Capella line of sight when the systematic errors associated with the uncertain intrinsic Procyon emission line are included. Further analysis of this and other lines of sight are planned to determine whether the D/H ratio varies within the local interstellar medium. We infer the primordial value of D/H from Galactic evolution models and comment on the derived baryon density of the Universe.

Key words

Deuterium cosmology interstellar medium 

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Copyright information

© Springer Science+Business Media Dordrecht 1994

Authors and Affiliations

  • Jeffrey L. Linsky
    • 1
    • 2
  • Athanassios Diplas
    • 3
  • Blair Savage
    • 4
  • Catherine Andrulis
    • 1
  • Alex Brown
    • 1
  1. 1.JILA/University of Colorado and NISTBoulderUSA
  2. 2.Quantum Physics DivisionNational Institute of Standards and TechnologyUSA
  3. 3.University of CaliforniaSan DiegoUSA
  4. 4.Astronomy DeptUniversity of WisconsinMadisonUSA

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