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Deuterium in the Local Interstellar Medium: Its Cosmological SignificanceWe 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) x 10(exp -5), T = 7000 K, and turbulent velocity 1.66 km/s. 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 x 10(exp -5) (+/- 3 sigma) 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.
Document ID
19970007593
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Linsky, Jeffrey L.
(Colorado Univ. Boulder, CO United States)
Diplas, Athanassios
(California Univ. San Diego, CA United States)
Savage, Blair
(Wisconsin Univ. Madison, WI United States)
Andrulis, Catherine
(Colorado Univ. Boulder, CO United States)
Brown, Alex
(Colorado Univ. Boulder, CO United States)
Date Acquired
August 17, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Frontiers of Space and Ground-Based Astronomy
Publisher: Kluwer Academic Publisher
Subject Category
Astrophysics
Report/Patent Number
NASA-CR-203146
NAS 1.26:203146
Accession Number
97N70579
Funding Number(s)
CONTRACT_GRANT: NASA Order S-56500-D
Distribution Limits
Public
Copyright
Public Use Permitted.
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