by Sándor Demes, on
Presentation of the workshop
How does the chemical complexity transform throughout the intricate process that culminates in the creation of a Sun and its accompanying planetary system? Does the chemical diversity observed in Solar-like planetary systems have its roots in the earliest stages of their formation, or does a complete chemical reset occur at some point? A potent approach for addressing these inquiries involves a comparative analysis of the chemical compositions found in interstellar clouds, young protostars and primitive celestial bodies within the Solar System, utilizing astrochemistry as a pivotal tool. However, to undertake such investigations effectively, a comprehensive comprehension of the mechanisms governing the chemical evolution from a molecular cloud to a nascent planetary system is essential.
By joining the efforts from observational measurements in combination with astrochemical modeling and laboratory experiments great advances have been done to improve our know-how on the chemical composition and evolution and space. More recently, computational chemistry based on quantum mechanical simulations and molecular modeling has recently been integrated into this fascinating interdisciplinary field by providing unprecedented and invaluable atomic-scale information to chemistry occurring in the Universe, which is fundamental to fully understand Astrochemistry, this way becoming at the new frontier and an indispensable hinge between the different astrochemical disciplines.
The overarching objective of this conference is to convene the key players in this inherently interdisciplinary pursuit, including observational astrochemists, computational chemists, experimentalists and astrochemical modelers. Recent substantial advancements in these domains have created an opportune moment for these communities to come together and collectively ride the crest of this scientific wave.
During this workshop, S. Demes presented his work as a speaker.
Accurate collisional excitation data for non-LTE modelling of large carbon cycles in cold ISM clouds - S. Demes, F. Lique, C. T. Bop, M. B. Khalifa, J. Cernicharo, and M. Agúndez
Recent astronomical surveys have revealed an entirely new, complex molecular picture of the interstellar medium (ISM) through the detection of cyclic and aromatic carbon species. Following the first detection of benzonitrile [1], other large cycles have been detected in cold ISM clouds, such as cyclopentadiene (C5H6) [2]. In order to correctly interpret these observations, a complex, non-LTE analysis is often needed. This requires the proper knowledge of state-to-state collisional rate coefficients, since molecular excitations are mainly driven by collisions in such environments. We report the first collisional data for a large cyclic species – cyclopentadiene – calculated from the most accurate coupled channel (CC) quantum theory. Until now, such data were published only for benzonitrile and benzene, calculated from approximate scattering theories, e.g. by the coupled states (CS) model. We show on the example of C5H6, that the CC rate coefficients deviate from those of the CS ones usually by a factor up to 2 at low temperatures, which can have a significant impact on radiative transfer models.
References
[1] B.A. McGuire et al. Science 2018, 359, 202.
[2] J. Cernicharo, M. Agúndez et al. A&A 2021, 649, L15, ibid 2023, 677, L13.
