Astronomy and Astrophysics Orfeus Ii Echelle Spectra: Deuterium and Molecular Hydrogen in the Ism towards Bd +39 3226

In ORFEUS II spectra of the sdO star BD +39 3226 interstellar hydrogen and deuterium is detected. From Ly α profile fitting and a curve of growth analysis of the Lyman series of H i and D i we derive the column densities NH = 1.20 −0.22·10 cm−2 and ND = 1.45 −0.38·10 cm−2. From the analysis of metal absorption lines in ORFEUS and IUE spectra we obtain column densities for 11 elements. In addition, we examine absorption lines of H2 for rotational excitation states up to J = 7. We find an H2 ortho-to-para ratio of 2.5, the fractional abundance of molecular hydrogen has a low value of log f = −4.08 for a total amount of N(H2) = 4.8 −1.6·10cm. The column densities of the excitation states reveal a moderate Boltzmann excitation temperature of 130 K and an equivalent excitation temperature for the excited upper states due to UV pumping of < 1800 K.