Browsing by Author "Vesterinen, Henrik"

Astrobiology is an interdisciplinary research field which studies the origin of life. One of the great challenges of modern observational astronomy in this area is to find building blocks of life in interstellar molecular clouds. These so-called biomolecules are under study in this thesis. First I present some fundamentals of radio spectroscopy and molecular structure. Then emphasis is put on observations made with the SEST- and APEX-telescopes of the objects NGC 6334F and IRAS 16293-2422. These objects represent the so-called hot cores. They are concentrations of gas and dust inside a molecular cloud where a new star is being born. One of the objectives in studying these hot sources is to find glycine NH2CH2COOH. Glycine is the most simple amino acid which means it is also a building block of our DNA. It has been hypothesised that several reaction chains may lead to glycine, either in gas phase or solid phase. Molecules that are part of the reaction chains that lead to glycine, are called precursors. Possible precursos of glycine are, for example, acetic acid and formic acid. The objective of this thesis is to find some of these precursors or their isomers. I have endeavoured to identify all molecular lines in the observed rotation spectra. This is done with the GILDAS/CLASS software package and specifically with its new Weeds extension. This has required estimation of the column density and then modifying its value until Weeds' model fits the observations. A lot of organic molecules were found. Glycine was not found and of its precursors only formic acid and methyl formate were found. However, the most interesting result was the detection of aminoethanol (NH2CH2CH2OH), which is a precursor of amino acid alanine (CH3NH2CHCOOH). Although this is only a tentative detection, it justifies a thorough investigation of future observations. Many of the observed spectral lines are blended so better resolution is needed. Many lines are also weak and are lost amid all the noise. The new ALMA interferometer will prove to be an invaluable tool in searching for new biomolecules. ALMA has very high angular and spectral resolution, high sensitivity, and large bandwidth. These properties are needed if we are to confirm or refute this new detection of aminoethanol.