Deuterium and Cosmology Research Programs

Deuterium is a relic of the primordial nucleosynthesis that occured between 100 and 1,000 seconds after the Big Bang. It is generally believed that since the Big Bang, deuterium has been destroyed but not created in nuclear reactions occuring inside of stars. We are analyzing Lyman resonance line absorption by interstellar deuterium and hydrogen seen in HST and FUSE spectra of nearby stars. The objective is to determine the D/H ratio and its possible variations in the interstellar gas clouds located in the disk of our Galaxy. The figure shows the D/H ratios that we have measured with HST spectra (diamonds) for lines of sight to nearby late-type stars as a function of distance to the star. Also plotted are D/H ratios obtained from FUSE spectra (squares) for stars both inside and outside the Local Bubble (log hydrogen column density < 19.2), from Copernicus (asterisks) and the IMAPS experiment (diamonds)..

Research Objectives:

• Measure the D/H ratio in local interstellar gas using Lyman-alpha line profiles seen in HST spectra of late-type stars
• Measure the D/H ratio in local interstellar gas using Lyman-beta and higher lines of the Lyman series in FUSE spectra of late-type stars and white dwarfs
• Test Galactic chemical evolution models using D/H and abundances of other elements

Important Results and Discoveries:

• Measured the D/H ratio in interstellar gas along lines of sight to many stars from high-resolution Lyman-alpha spectra obtained with the FUSE, HST and Copernicus satellites.
• Measured the D/H ratio in interstellar medium gas within about 200 pc of the Sun. This value has been generally accepted since 2006 and is highly cited.
• Showed that the D/H ratio elsewhere is the Galaxy is highly variable and can be explained by the preferential absorption of deuterium atoms on the surfaces of interstellar grains.
• Estimated the primordial D/H ratio from the observed variations in the D/H ratio in the Galaxy. The primordial D/H ratio is a critical constraint on models of the early Universe.

Papers published in refereed journals since 2000:

• Linsky, J.L. et al.: 2006, "What is the total deuterium abundance in the local Galactic disk?", Astrophysical Journal 647, 1106
• Wood, B.E., Linsky, J.L., Hebrard, G., Williger, G.M., Moos, H.W., and Blair, W.P.: 2004, "Two new low Galactic D/H measurements from FUSE", Astrophysical Journal, 609,838
• Moos, H.W. et al.: 2002, "Abundances of deuterium, nitrogen, and oxygen in the local ISM: Overview of the first results from the FUSE mission", Astrophysical Journal Supplement Series, 140, 3
• Wood, B.E., Linsky, J.L., Hebrard, G., Vidal-Madjar, A., Lemoine, M., Moos, H.W., Sembach, K.R., and Jenkins, E.B.: 2002, "Deuterium abundance toward WD 1634-573: Results from the FUSE mission", Astrophysical Journal Supplement Series, 140, 91
• Hebrard, G., et al.: 2002, "Deuterium abundance toward WD 2211-495: Results from the FUSE mission", Astrophysical Journal Supplement Series, 140, 103
• Kruk,J.W., et al.: 2002, "Abundances of deuterium, nitrogen, and oxygen toward HZ 43: Results from the FUSE mission", Astrophysical Journal Supplement Series, 140, 19

Review Papers conference papers since 2000: