| タイトル | Molecular and atomic clouds associated with infrared cirrus in Ursa Major |
| 著者（英） | De Vries, Hendrik Willem; Heithausen, Andreas; Thaddeus, Patrick |
| 著者所属（英） | Columbia Univ.|Bonn Univ.|NASA Goddard Inst. for Space Studies |
| 発行日 | 1987-08-15 |
| 言語 | eng |
| 内容記述 | Observations of CO and H I revealed that in Ursa Major the high-latitude far-infrared 'cirrus' emission discovered by the Infrared Astronomical Satellite comes from molecular and atomic clouds. These clouds differ sufficiently from the large clouds in the Galactic plane so that the ratio of H2 column density to velocity-integrated CO radiation temperature, N(H2)/W(CO), derived from Galactic plane surveys, may not apply to them. On the assumption of a constant gas-to-dust ratio, it is argued that the cirrus emission in Ursa Major is a good mass tracer, since both the atomic and the molecular gas are probably optically thin at visual wavelengths, and the grains are heated not by local sources but by the background field of Galactic starlight. The N(H2)/W(CO) ratio thus derived for those diffuse clouds, is significantly lower than the ratio applicable to Galactic plane surveys. |
| NASA分類 | ASTROPHYSICS |
| レポートNO | 87A52112 |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/375868 |
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