New theoretical grounds in Astrochemistry

For the first time, NANOCOSMOS has attempted to reproduce the complex molecular chemistry and stardust formation in circumstellar envelopes (CSEs) of asymptotic giant branch (AGB) stars and interstellar environments under accurate and realistic laboratory conditions. These conditions differ from previous studies and techniques to produce stardust analogs, mostly based on laser ablation and pyrolysis, flames, and other far related conditions from those in the CSEs of AGB stars.

Hence, we have used our innovative setups at CSIC and CNRS, e.g. Stardust, AROMA, PIRENEA 2 and cold plasma reactors, to study the processes that lead to carbon dust formation including polycyclic aromatic hydrocarbons (PAHs) and fullerenes. We have studied the chemistry of atomic silicon and the formation of silicate dust grains. We have also investigated the aromatic content of two different meteorites, Murchison and Almahata Sitta.

In summary, our synergetic results provide significant and surprising breakthroughs in our current understanding of the chemical processes at play in CSEs and meteoritic samples. These new and open theoretical grounds have also important implications in current chemical models. These NANOCOSMOS breakthroughs are the following:

  • Aliphatic nature of carbonaceous cosmic dust analogs. Our realistic laboratory conditions do not lead to the efficient formation of aromatic molecules (PAHs and fullerenes) in the gas phase, contrary to all previous studies (Stardust, AROMA).
  • Efficient mechanism for the formation of silane and disilane in the gas phase from Si, H, and H2 in the innermost regions of the CSEs around AGB stars (Stardust).
  • Further evidence for the role of metal (iron) seeds to increase not only the formation of metal clusters but also catalyzed hydrocarbon growth in the CSEs of AGB stars (Cold plasma reactors, AROMA, PIRENEA 2 and ESPOIRS).

  • First firm detection of fullerenes in meteorites (Almahata Sitta) and co-existence of carbon clusters along with PAHs in this meteorite (AROMA).

    High-Resolution Submillimeter Spectroscopy of the Interstellar Medium and Star Forming Regions — From Herschel to ALMA and Beyond (Zakopane, Poland, May 12 – 16, 2015)

    copyright © : Subaru Telescope, National Astronomical Observatory of Japan (NAOJ)
    copyright © : Subaru Telescope, National Astronomical Observatory of Japan (NAOJ)

    Two NANOCOSMOS members, Prof. José Cernicharo and Dr. Javier R. Goicoechea gave two invited talks at this workshop in Poland. José Cernicharo showed the NANOCOSMOS latests results from the ALMA observations of the archetypical AGB carbon-star IRC+10216. The NANOCOSMOS team has published 4 articles (see publications) on these results (including IRAM observations) and new exciting results are expected for the coming months. Javier R. Goicoechea talked about the velocity-resolved [CII] emission and [CII]/FIR mapping along Orion. The [CII] 158μm fine structure line is arising in gas irradiated by UV-photons from the Trapezium cluster and contributes significantly to the cooling of the cold neutral medium. These observations in combination with Far-Infrared photometric images of the dust emission and maps of the H41α hydrogen recombination and CO provide an unprecedented close view (0,16 light-years in resolution) of the Orion Cloud surrounding the Trapezium. Stay tuned¡