Astrochemistry

Astrochemistry is an interdisciplinary field which comprises astronomical observations, theoretical models and laboratory experiments aimed at understanding the physical and chemical processes which determine the composition of the interstellar gas and dust. The gas chemical composition strongly depends on the local density, temperature, gas ionization degree and radiation conditions. Molecules with a well-understood chemistry can therefore be used as probes of astrophysical phenomena. In this context, molecules are a valuable tool to increase our knowledge of the Universe at all scales from the entire galaxy to planetary atmospheres.

The chemistry of the interstellar gas regulates key aspects of star and planet formation. Large molecular clouds can fragment into dense cores to a large extent because molecules cool the gas, thus diminishing the thermal support relative to self-gravity. Moreover, the abundances of some atoms such as carbon Carbon and Sulfur determine the ionization fraction which controls the coupling of magnetic fields with the gas. The formation of dense cores and its subsequent collapse is hence related to the gas chemical composition.

The chemical composition of the interstellar gas and dust is also interesting by its own right. Dust grains are the prime material from which planets are formed and an accurate knowledge of their composition is essential for planet formation studies. Although the direct observation of grains composition is challenging, gas-grain chemical models have increased in complexity and now we can obtain a hint for their composition from the combination of high sensitivity observational data and sophisticated chemical modeling. In the deep interior of molecular clouds, grains become covered by water-rich icy mantles where complex organic compounds are formed. These species may be ultimately delivered to terrestrial planets when planetary systems are formed. The fate of some molecules such as water and complex organics are specially interesting because of their connection with the origin of life.

Astrochemists in the National Astronomical Observatory are primarily engaged in the understanding of the chemical composition of molecular clouds in the context of star formation and planet formation. The last generation of large (sub-)millimiter telescopes (40m Yebes telescope, Pico Veleta, NOEMA, ALMA) allows us to follow the chemistry of the interstellar material from molecular clouds to protoplanetary disks, from which planets and their atmospheres will be formed.