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Accueil > Séminaires > Année 2019 > Séminaire de Kin Long Kelvin Lee (3 sept 2019)

Séminaire de Kin Long Kelvin Lee (3 sept 2019)

Center for astrophysics, Harvard & Smithsonian

par Martrenchard-Barra Séverine - 25 août 2019

Interstellar Aromatic Chemistry

Aromatic hydrocarbon molecules such as benzene (c-C6H6) demonstrate peculiar thermodynamic stability and chemical inertness. Thus, aromatic species are expected to be relatively prevalent in the interstellar medium - mainly in the form of polycyclic aromatic hydrocarbons (PAH) - where they are able to survive the harsh environments dominated by shocks and radiation. In spite of chemical intuition, aromatic chemistry as a field of research in space has remained relatively elusive ; no single PAH has been identified in space due to their broad and non-unique infrared absorption spectra, and smaller aromatics like benzene and naphthalene do not possess a permanent dipole moment, and are therefore invisible in the radio.
The recent discovery of benzonitrile (c-C6H5CN) - a polar analog of benzene - by McGuire and co-workers in the cold, dark molecular cloud TMC-1 with the 100 m Green Bank Telescope (GBT) has opened up a new avenue of interstellar chemistry, demonstrating derivatives of otherwise non-polar aromatic hydrocarbons can now be detected using radio-based methods, which have been the main workhorse for molecular astrophysics. The questions that we now seek to answer will extend the benzonitrile detection beyond novelty : how widespread is aromatic chemistry, and what role does it play in the chemical and physical dynamics of interstellar environments ? In this talk, I will present the combined observational, laboratory, and theoretical efforts to answer these questions, all of which stem from two large GBT projects, ARKHAM and GOTHAM. I will discuss laboratory and theoretical studies into how aromatic rings may form under low-temperature conditions, and preliminary results from the large GBT observational campaigns.

Séminaire de Kin Long Kelvin Lee - 150.8 kio

3 sept 2019