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Intermediate scale structure of the interstellar medium towards NGC 6231 in Sco OB1 with FUSE
The FUSE far-ultraviolet interstellar spectra toward seven targets inNGC 6231 show that the molecules H2, HD,and CO as well as various atomic species are distributed in severalclouds. The main absorption component found on the sight lines lies inthe Lupus cloud region at a distance of about 150 pc, and there is aweaker second one, presumably in the Sco OB1 shellsurrounding NGC 6231 (d≃1.8 kpc). H2excitation modelling is used to constrain the radiation field and thedensity in the gas; HD is used to estimate the abundance ofH+. The small angular separation of the target stars allowscolumn density variations to be probed over the field of view, on scalesof 0.05 pc in the case of the Lupus cloud distance. They are 40% forH2 and 60% for H I. A rather strong radiation field insidethe molecular clouds suggests a separation of the gas into smallercloudlets also along the line of sight.Based on observations made with the NASA-CNES-CSA Far UltravioletSpectroscopic Explorer. FUSE is operated for NASA by the Johns HopkinsUniversity under NASA contract NAS5-32985.
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
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