Origins: From the Protosun to the First Steps of Life Proceedings IAU Symposium No. 345, 2018 B. G. Elmegreen, L. Viktor T´oth & M. G¨ udel, eds. c  International Astronomical Union 2020 doi:10.1017/S1743921319002138 Unveiling the whole from its parts or to see the forest for the trees Eduardo Janot-Pacheco 1 , Marina Rachid 1 , Philippe Bendjoya 2 , Armando Domiciano 2 , Caroline Antunes-Rosa 3 , Marcelo Emilio 4 and Claudia Lage 3 1 Institute of Astronomy, Geophysics and Atmospheric Sciences, So Paulo University, Brazil email: eduardo.janot@iag.usp.br 2 Universit´ e Cˆote d’Azur, Observatoire de la Cˆ ote d’Azur, CNRS, Laboratoire Lagrange, France email: Philippe.BENDJOYA@unice.fr 3 Carlos Chagas Filho Institute of Biophysics, Rio de Janeiro Federal University, Brazil email: lage@biof.ufrj.br 4 Ponta Grossa State University, Brazil email: marcelo emilio@yahoo.com Abstract. If biologically complex molecules as DNA were present in the extraterrestrial targets, their spectral signatures would be rather difficult to be unambiguously identified. As a matter of fact, the molecular array of a single nucleobasis will generate a tangled spectral signature. On the other hand, a part of it, e.g. bands due to the group of HNCO of guanine may have been detected but associated to smaller molecules, e.g. isocianic acid (HNCO). However, if comprised in a nucleobasis, its detection would be misinterpreted. Five key transitions were preliminarly selected for either purines and pyrimidines that should be observed together in the same target. If this happens, it may be that we are detecting the whole from its parts. Keywords. ISM: molecules, ISM: lines and bands, astrochemistry 1. Introduction We live in a molecular universe. In a spiral galaxy as the Milky Way (MW), interstellar molecular clouds are the bigger and heavier baryonic components of the spiral system. The largest molecular clouds are visible to the naked eye, appearing as dark patches against the brighter background of the MW. They can be seen all over the magnificent projection of the galaxy disk on the sky, mainly from the southern hemisphere. Biology tell us that more than 95 % of all life forms on Earth is composed by H, O, C N, P and S, sources of the known CHONPS anagram. Moreover, the genetic material of all life forms is encoded in huge molecules, formed by the long sequences of deoxyribonucleic or ribonucleic acids (DNA and RNA). 2. Molecular factories It is well known that interstellar molecular clouds and circumstellar envelopes harbour ice grains that can act as factories of molecular synthesis. Indeed, atoms and molecules can meet and react at the surface of the ices present in the clouds, the cosmic rays and energetic photons acting as the necessary energy source for ionization and chemical reactions (e.g. Marshall & Sadeghpour 2016). 215 https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1743921319002138 Downloaded from https://www.cambridge.org/core. IP address: 3.88.199.6, on 06 Sep 2021 at 14:16:49, subject to the Cambridge Core terms of use, available at