Presentation 1 : Oral
First deuterium results with FUSE (PNC)
G. H\'ebrard
Deuterium abundance measurements allow constraints to be put on the
Big Bang Nucleosynthesis, the baryonic content of the Universe,
and the chemical evolution of galaxies. Such measurements in a variety
of astrophysical environments are one of the main objectives of the
Far Ultraviolet Spectroscopic Explorer (FUSE) mission. The first
results are presented here.
Beside a tentative detection in Jupiter, deuterium absorption lines
are seen toward a few extragalactic targets and tens of interstellar
sight lines. In the local interstellar medium (within 100 pc),
it is likely that the D/H and D/O ratios have both a single
value in the local interstellar medium. They may present spatial
variations beyond the Local Bubble.
Presentation 2 : Poster
Quasi-molecular satellites in cool white dwarfs; Application to FUSE observations of G231-40 (PNPS)
G. H\'ebrard, N. F. Allard, I. Hubeny, S. Lacour, R. Ferlet, A. Vidal-Madjar
Comprehensive calculations of the Lyman-alpha and Lyman-beta line wings
which include perturbations by both neutral hydrogen and protons and all
possible quasi-molecular states of H2 and H2+ are used to predict synthetic
spectra for cool DA white dwarfs. They are compared with FUSE observation
of G231-40.
The appearance of the line wings between Lyman-alpha and Lyman-beta is
shown to be sensitive to the relative abundance of hydrogen ions and neutral
atoms, and thereby to provide a temperature diagnostic for stellar atmospheres
and laboratory plamas.