AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 71. Between the Stars II: The ISM, Galactic and Extragalactic
Display, Wednesday, June 2, 1999, 10:00am-6:30pm, Southwest Exhibit Hall

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[71.02] Alcohol Chemistry: Tentative Detections of Two New Interstellar Big Molecules CH3OC2H5 and (C2H5)2O

Y.-J. Kuan (Nat'l Taiwan Normal U. \& ASIAA), S.B. Charnley (NASA/Ames \& UC-Berkeley), T.L. Wilson (SMTO/U. Arizona), M. Ohishi (NAO Japan), H.-C. Huang (Nat'l Taiwan Normal U.), L.E. Snyder (UIUC)

Recent modeling of gas-grain chemistry demonstrated that many of the organic species are not the products of grain-surface reactions but are in fact synthesized in the warm gas from simpler species produced on grains. To test gas-grain chemistry, in particular alcohol chemistry, we have thus searched for (C2H5)2O (diethyl ether) and CH3OC2H5 (methyl ethyl ether), using the NRAO 12-m, in the giant molecular cloud cores Sgr B2(N), W51 e1/e2 and Orion-KL, where alcohols have been evaporated from ice mantles. In addition, we have also used the BIMA array to observe the 3-mm transitions of the two molecules toward Sgr B2.

The preliminary 12-m results indicate clean detections of various line transitions of the two molecular species in the 1-mm, 2-mm and 3-mm regimes in all 3 molecular cloud cores. Furthermore our BIMA maps show a clear concentration of CH3OH toward Sgr B2(N), the Large Molecule Heimat; sole detections of CH3OC2H5 and (C2H5)2O toward Sgr B2(N), instead of the more evolved Sgr B2(M), are also observed unambiguously as predicted by alcohol chemistry. Our detections of the two complex molecules not only further confirm the gas-grain chemistry but also require specifically that methanol (CH3OH) and ethanol (C2H5OH) to be formed in grain mantles. In addition, the detections of diethyl ether and methyl ethyl ether lead to the discovery of two new molecules, including the largest ever, (C2H5)2O.

This work was partially supported by: NSC grants 87-2112-M-003-007 and 88-2112-M-003-013 of Taiwan, National Taiwan Normal University, Academia Sinica Institute of Astronomy and Astrophysics, NSF AST 96-13999, the University of Illinois, and NASA's Exobiology Program.

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