Year: 2006
Type: article
Abstract: Analyses of spectra obtained with the Far Ultraviolet Spectroscopic Explorer ( FUSE ) satellite, together with spectra from the Copernicus and interstellar medium absorption profile spectrograph (IMAPS) instruments, reveal an unexplained, very wide range in the observed deuterium/hydrogen (D/H) ratios for interstellar gas in the Galactic disk beyond the Local Bubble. We argue that spatial variations in the depletion of deuterium onto dust grains can explain these local variations in the observed gas-phase D/H ratios. We present a variable deuterium depletion model that naturally explains the constant measured values of D/H inside the Local Bubble, the wide range of gas-phase D/H ratios observed in the intermediate regime [log N (H ) = 19.2-20.7], and the low gas-phase D/H ratios observed at larger hydrogen column densities. We consider empirical tests of the deuterium depletion hypothesis: (1) correlations of gas-phase D/H ratios with depletions of the refractory metals iron and silicon, and (2) correlation with the H 2 rotational temperature. Both of these tests are consistent with deuterium depletion from the gas phase in cold, not recently shocked regions of the ISM, and high gas-phase D/H ratios in gas that has been shocked or otherwise heated recently. We argue that the most representative value for the total (gas plus dust) D/H ratio within 1 kpc of the Sun is ≥23.1 ± 2.4(1 σ) parts per million (ppm). This ratio constrains Galactic chemical evolution models to have a very small deuterium astration factor, the ratio of primordial to total (D/H) ratio in the local region of the Galactic disk, which we estimate to be f d ≤ 1.19 (1 σ) or ≤1.12 ± 0.14(1 σ) depending on the adopted light-element nuclear reaction rates.
Source: The Astrophysical Journal
DOI: 10.1086/505556
Authors: Jeffrey L. Linsky, Bruce T. Draine, H. W. Moos, Edward B. Jenkins, Brian E. Wood, Cristina Oliveira, William P. Blair, Scott D. Friedman, Cecile Gry, David Knauth, Jeffrey W. Kruk, Sylvestre Lacour, Nicolas Lehner, Seth Redfield, J. Michael Shull, George Sonneborn, Gerard M. Williger
Institutions: National Institute of Standards and Technology, Joint Institute for Laboratory Astrophysics, Princeton University, Johns Hopkins University, Space Telescope Science Institute, Laboratoire d’Astrophysique de Marseille, Northwestern University, Observatoire de Paris, Laboratoire d’études spatiales et d’instrumentation en astrophysique, University of Wisconsin–Madison, McDonald Observatory, The University of Texas at Austin, University of Colorado Boulder, Goddard Space Flight Center
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W1970514469