English  |  正體中文  |  简体中文  |  全文筆數/總筆數 : 49378/84106 (59%)
造訪人次 : 7365040      線上人數 : 78
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library & TKU Library IR team.
搜尋範圍 查詢小技巧:
  • 您可在西文檢索詞彙前後加上"雙引號",以獲取較精準的檢索結果
  • 若欲以作者姓名搜尋,建議至進階搜尋限定作者欄位,可獲得較完整資料
  • 進階搜尋
    請使用永久網址來引用或連結此文件: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/72736

    題名: Dense gas in nearby galaxies: VIII. The detection of OCS
    作者: Chin, Y.N.;R. Mauersberger, C. Henkel
    貢獻者: 淡江大學物理學系
    日期: 1995-02
    上傳時間: 2013-05-31 11:31:59 (UTC+8)
    出版者: Les Ulis: EDP Sciences
    摘要: The detection of extragalactic OCS, the heaviest molecule identified outside the Galaxy, is reported in three rotational transitions toward the bulge of NGC253. Toward M82, OCS has been tentatively detected. Abundances are consistent with models for warm, dense clouds which have not yet reached chemical equilibrium or with the frequent erosion of grain mantles by C-shocks. This can also explain the large abundances of complex molecules in NGC253. Densities and temperatures of the OCS emitting gas are compared with results from other molecular tracers. From model computations, OCS in the center of NGC253 is emitted by a moderately dense molecular component with n(H2) ~ 103.4 /cm3. This component makes up the bulk of the molecular gas mass. Other molecules also reveal the presence of a much denser component with 10(5-5.5) /cm3. A molecular gas mass of ~ 2 × 108 solar masses is estimated for a 180pc sized molecular cloud toward the center of NGC253; the mean H2 density is ~ 2000 /cm3; and the mean H2 column density, 7 × 1023 /cm2, corresponds to a visual extinction of 700m. The relative OCS abundance is X(OCS) ~ 10-8.9. From detections of the J=2-1 and 3-2 transitions of C34S, the density of the dense molecular gas toward the nuclear region of IC342 is n(H2) ~ 104.6 /cm3. Also presented are a possible detection of the HC3N J=16-15 line toward IC342 and upper limits for the emission of the DCN J=2-1 line toward NGC253 and IC342. For NGC253, [DCN]/[HCN] <= 4 × 10-3.
    關聯: Astronomy and Astrophysics 294, pp.23-32
    顯示於類別:[物理學系暨研究所] 期刊論文





    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library & TKU Library IR teams. Copyright ©   - 回饋