Methyl silane (CH3SiH3) and silyl cyanide (SiH3CN, first time in Space)
We propose a formation mechanism through catalytic reactions on the surface of dust grains by hydrogenation of silicon-carbon species in the inner dust formation zone
Formation of SiC dust in C-rich AGBs
SiC2, CS, SiO and SiS gas-phase precursors of dust
Decline in the abundances of these molecular species with increasing density in the envelopes of C-rich AGB stars. Important constraints for Stardust experiments on SiC dust formation.
Formation of dust in O-rich AGBs
SiO and SO gas-phase precursors of dust
Decline in the abundances of these molecular species with increasing density in the envelopes of O-rich AGB stars
Discovery of molecular species in the Interstellar Medium
7 molecules, including one protonated form and isotopologs (2 of them, first time in Space)
See dedicated descriptions below (under construction)
Major NANOCOSMOS highlights in “ALMA/IRAM observations” (see dedicated descriptions below)
NANOCOSMOS has performed several key observations of the circumnuclear envelopes -CSEs- of AGB stars with the IRAM 30m radio telescope and the ALMA interferometer. These observations are mandatory to foster the study of the gas-phase precursors of dust in these envelopes. We have made fruitful efforts in the study of the Si-C chemistry in these objects.
NANOCOSMOS has discovered methyl silane, CH3SiH3 and silyl cyanide (SiH3CN) in the envelope of the C-rich AGB star IRC +10216. We suggest that both are formed in the inner zones of the circumstellar envelope through catalytic reactions on the surface of dust grains by hydrogenation of silicon-carbon species.
We have also performed two molecular surveys with the IRAM facility, one to study the envelopes of 25 C-rich AGB stars to search for emission lines of SiC2, SiC, Si2C, CS, SiO and SiS and another one with a sample of 30 O-rich AGB stars to investigate the potential role of SiO, CS, SiS, SO, and SO2 in the formation of dust in these environments.
Our results show strong evidences that the observed decline in the molecular abundances of these species with increasing density in the envelopes are due to their incorporation to the solid phase. Furthermore, we establish that SiC2, CS, SiO and SiS (tentatively) are very likely gas-precursors of SiC dust in C-rich envelopes of AGB stars and SiO and SO (tentatively) in O-rich AGB stars.
Finally, the team has detected 7 molecules in the Interstellar Medium, some of them of key importance to constrain chemical models. These are the c-C3D isotopologs, the metastable and polar isomer isocyanogen (CNCN), the isocyanate radical NCO, the thioformyl radical (HCS) and its metastable isomer HSC, all of them in the dark cold cloud core L483, which contains a low-mass protostar. We have also detected ethyl formate (CH3CH2OCOH) and NS+ in the young protostellar system Barnard 1b with ALMA and IRAM respectively.
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 in cold molecular clouds 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.
These achievements are based on groundbreaking innovative setups at CSIC and CNRS, e.g. Stardust, AROMA, PIRENEA 2 and cold plasma reactors, that foster the study of complex 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, the interstellar medium (ISM) 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 in CSEs. 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)
First detection of a pure PAH (indene) in the TMC-1 cold dark molecular cloud. This is totally an unexpected discovery and suggests an in-situ bottom-up formation process in these environments from smaller molecules in the gas-phase (Yebes 40m radio telescope + new mm receivers).
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).
NANOCOSMOS has successfully achieved significative breakthroughs to address the fundamental problem of cosmic dust formation. We have designed and implemented innovative experimental set-ups and analytical tools well beyond the state-of-the-art. Next we describe the design, construction, implementation and commissioning of these innovations in the dedicated links:
NANOCOSMOS is providing new exciting experimental results in different research fields and challenging theoretical grounds. This menu is devoted to the description and analysis of Outstanding Results and potential new challenges.
The paper “Compression and ablation of the photo-irradiated molecular cloud the Orion Bar” (Goicoechea et al. 2016) recently published in Nature, has put Astrochemistry and NANOCOSMOS in the leading edge forefront of many research institutIons, newspapers and mass media. A few examples can be found below:
The second announcement of the European Conference on Laboratory Astrophysics – “Gas on the Rocks” – ECLA 2016 has been issued today. This conference will be held at the CSIC headquarters (Madrid, Spain) in November 21 – 25, 2016. The webpage is open with all the relevant information.
More than 30 invited researchers will address new insights on the following science topics:
Comets, asteroids, meteorites and the primitive Solar System nebula: formation and evolution
Protoplanetary disks and planet formation
Planet, Moon, and exoplanet surfaces and atmospheres
The signatures of the evolving interstellar medium
Dense Clouds: the gas-ice interface and molecular complexity
Chemical fingerprints of star formation
The late stages of star evolution: dust formation
Supernovae and shocks: high-energy processing of matter