Complex molecules in galactic dust cores: Biologically interesting molecules and dust chemistry

Details Complex molecules in galactic dust cores: Biologically interesting molecules and dust chemistry Complex molecules in galactic dust cores: Biologically interesting molecules and dust chemistry

Jun 2000

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000phdt........16l&link_type=abstract

Thesis (PhD). UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN, Source DAI-B 60/12, p. 6152, Jun 2000, 129 pages.

Mathematics

Logic

1

Scientific paper

The astronomical study of molecules has been an essential research field since the development of radio astronomy. Presently nearly 120 molecules have been identified in interstellar and circumstellar environments. The complexity of molecular species, and particularly organic molecules, that can be synthesized in the interstellar medium (ISM) leads to one interesting and important subfield in interstellar molecular studies, namely, the search and study for molecules of possible biological interest. Observationally, complex and most saturated molecules are observed exclusively toward compact hot, dense regions, often called ``hot cores'', in molecular clouds. To account for the observed amount of saturated organic molecules, interstellar dust particles play an important role. It has often been suggested that solid state reactions on grain surfaces provide an efficient way to synthesis saturated organic molecules. The objective of this study is to obtain observational data on biologically interesting molecules and to study important complex interstellar molecules. Since hot molecular cores are inherently compact, interferometric observations are therefore an ideal approach to study these sources. All our observations were all made with the Berkeley-Illinois-Maryland-Association (BIMA) Array. We conducted the first survey of formic acid (HCOOH) with an interferometric array, and identified at least three sources. HCOOH is found with column densities above 1015 cm-2 in these sources. The correlation between HCOOH and HCOOCH3 emission implies a surface chemistry origin of HCOOH. Details of the results are given in Chapter 2. Meanwhile, we continued to search for molecules of biological interest, namely urea, acetic acid, and glycine. In Chapter 3, the results of column density limits set by our observations are discussed. We have also investigated properties of individual hot molecular cores. It is very important to obtain the physical and chemical properties of these cores in order to understand the formation mechanisms for complex organic molecules. Chapter 4 presents the results from our Sgr B2 observations of molecules including silicon monoxide (SiO), a main component in the refractory core of silicate grain particles, and vinyl cyanide (C2H3 CN) and ethyl cyanide (C2H5CN), molecules suggested to be formed predominantly through gain surface reactions. The enhanced SiO abundance in Sgr B2(M) and the high column densities of C2H 3CN and C2H5CN found in Sgr B2(N) indicate a chemical differentiation between Sgr B2(N) and Sgr B2(M). It appears that Sgr B2 (N) is at an earlier evolutionary stage which results in the low abundance of SiO but high abundances of complex molecules in the gas phase. The picture is consistent with the current dust chemistry models. Moreover, it is significant that the spatial resolution achieved in our observations corresponds to the size of our solar nebula at the distance of the galactic center. In Chapter 5, we show that HCOOH appears to exist ubiquitously in dense molecular cores in either solid or gas phase. The detected HCOOH sources are good candidate targets for future acetic acid and glycine searches. Preliminary results from new 1 mm band observations toward Sgr B2 and Orion KL are also presented. Future prospects are given at the end.

Affiliated with

Also associated with

No associations

Rating

Complex molecules in galactic dust cores: Biologically interesting molecules and dust chemistry does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Complex molecules in galactic dust cores: Biologically interesting molecules and dust chemistry, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Complex molecules in galactic dust cores: Biologically interesting molecules and dust chemistry will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1247648