Kwang-Il Seon

FUV Interstellar Absorption Toward the Lupus Loop Region (abstract)

Far‐ultraviolet (FUV) observation of interstellar absorption toward the Lupus Loop region (SNR 330.0+15.0) is presented. Using Hipparcos, more accurate distance estimates to 52 B‐type stars in Lupus are obtained. When a distance of 155±8 pc to the supernova remnant is adopted, most stars seem to lie in the foreground. Seven stars lie in the background, allowing a clearer interpretation of absorption lines. Prior to Hipparcos, research suffered from distance uncertainties, leading to confusion as to whether the origin of an observed absorption line was stellar or interstellar. FUV emission studies detected ionic lines inferred to be tracers of warm and hot (104<106° K) interstellar plasma. Important cooling lines (e.g., C IV, O VI, S II, and N IV) from diffuse warm gas have been reported. Assuming that these lines are caused by the same plasma, a detailed absorption analysis is performed toward seven background stars in Lupus. The ionic lines detected in emission are also well detected in absorption, sugge...

ORFEUS SURVEYS OF THE INTERSTELLAR MOLECULAR HYDROGEN

We present measurements of interstellar absorption lines in the continuum spectra of 54 early-type stars in the Galactic disk and halo and 3 stars in the Magellanic Clouds. The data were obtained with the Berkeley Extreme and Far-Ultraviolet Spectrometer (BEFS), part of the ORFEUS telescope, which flew on the ORFEUS-SPAS I and II space-shuttle missions in 1993 and 1996, respectively. The spectra extend from the interstellar cutoff at to about with a spectral resolution of and statistical signal-to-noise ratios between 10 and 65. Assuming a velocity profile derived from optical observations (when available), we model the column densities N(J) of the rotational levels J