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Session 49 - The Frontiers of Far Ultraviolet Astrophysics - I.
Topical, Oral session, Wednesday, June 10

[49.01] FUV, Introduction

G. Sonneborn (NASA's GSFC)

A one-day topical session will review the observational and theoretical status of astrophysical problems where data in the 900 to 1200 Å\ range are essential for future advances. The session will include the study of FUV rest wavelengths at high redshifts. For example, the status of the deuterium-to-hydrogen abundance ratio will address the Milky Way and QSO absorption line systems. The FUV spectral region is well known for its unique spectral features and important scientific problems they address. The Lyman series of atomic hydrogen provides the only means to determine the production of deuterium in the Big Bang and its subsequent processing during galactic chemical evolution. The resonance doublet of the O VI ion is the highest temperature resonance line available to study the abundance and kinematics of diffuse hot gas in the disk and halo of the Galaxy and hot gas in accretion disks. The Lyman and Werner bands, the only electronic transitions of molecular hydrogen, probe cold gas in the diffuse ISM as well as the outer regions of dense molecular clouds. Strong transitions of several ionization states of carbon, nitrogen, oxygen, neon, sulphur, and argon provide unique diagnostics for studying interstellar gas and emission plasmas. This special session focuses on recent observational material and how the data limit the range of acceptable pictures. It is also intended to highlight key puzzles and describe anticipated progress from new instrumentation, in particular the Far Ultraviolet Spectroscopic Explorer mission, due to be launched in early 1999.

Program listing for Wednesday