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).
NANOCOSMOS successfully designed and constructed two new millimeter broad band receivers for the Q frequency band (31.5 − 50 GHz) and the W band (72 − 90.5 GHz) for the Yebes 40m radio telescope. One of our main achievements is the instantaneous frequency coverage in order to observe many molecular transitions with single tunings in single-dish mode.
Our Yebes observations have led to the discovery of multiple molecular species. These were made in 2019 (Q2, Q4), and 2020 (Q1) and were complemented with the IRAM 30m radio telescope in Granada (W band).
Objects: IRC+10216 as the archetypal AGB carbon rich star and the cold dark Taurus Molecular Cloud -1 or TMC-1.
Methodology: observations, laboratory characterization, ab-initio quantum calculations, rotational diagrams, gas-phase chemical models and radiative transfer calculations.
Summary of results with the NANOCOSMOS mm broad band receivers at Yebes 40m radio telescope:
Sulfur-bearing species NCS, HCCS, H2CCS, H2CCCS, and C4S – First time discovery in Space (TMC-1)
C5S – First time detection in a cold dark cloud (TMC-1)
State-of-the-art gas-phase chemical networks fail to reproduce the observed column densities. Thus, important reactions involving S and S+(neutral-neutral, neutral-ion) and those on dust grain surfaces are missing and much laboratory and theoretical work need be performed in order to understand the chemistry of sulfur
The analysis of C4S and C5S shows that S-bearing carbon chains do not follow the smooth decrease in abundance observed in cold dark molecular clouds and circumstellar envelopes for other carbon chains such as cyanopolyynes (HC2n + 1N; a factor 3–5 between members of this molecular species)
Propargyl radical (CH2CCH) 6 strongest hyperfine components of the 20, 2–10, 1 rotational transition – First time discovery in interstellarr Space (TMC-1)
Similar abundance as methyl acetylene. Thus, it is one of the most abundant radicals detected in TMC-1. Moreover, it is probably the most abundant organic radical with a certain chemical complexity ever found in a cold dark cloud
The observed high abundance, points out that CH2CCH probably plays a key role in the synthesis of large organic molecules and, in particular, the cyclization towards the first aromatic ring (benzene). This also happens in combustion processes where the CH2CCH radical has a key role in the synthesis of benzene and polycyclic aromatic hydrocarbons (PAHs).
Allenyl Acetylene (H2CCCHCCH) 19 rotational transitions – First time detection in Space (TMC-1)
We find that allenyl acetylene and methyl diacetylene are the two most stable C5H4 isomers and both have similar observed abundances in TMC-1
State-of-the-art chemical models understimate the observed abundances by an order of magnitude. We need to assess the main formation routes in the chemical models, mainly the reactions of the CCH radical with methyl acetylene (CH3CCH) and allene (H2CCCH2)
HC3S+ (4 lines) – First time detection in Space (TMC-1), laboratory production and characterization of the protonated form of C3S
The spectroscopic parameters obtained for HC3S+ from ab initio calculations agree very well with that obtained from observations and in the laboratory
Constraint in chemical formation routes: The derived C3S/HC3S+ ratio is well reproduced by a gas-phase chemical model in which HC3S+ is mostly formed through protonation of C3S and the reactions S+ + C3H2 and S + C3H3+
HC4NC (5 lines, Q band) – First time detection in Space
Cold molecular clouds favor the formation of metastable isomers due to their low temperatures.
In the ejecta of AGB stars, where the temperature is higher, the presence of high-energy isomers is less favorable because chemical reactions, including isomerization, are expected to favor the most stable isomer. The same pattern is expected for isotopic fractionation
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 Nanocosmos team published in October 21, 2019, at Nature Astronomy (available free at Europe PubMed Central), the results of a set of laboratory experiments showing that gas-phase chemistry, under conditions similar to those of a red giant star environment, can produce very efficiently small amorphous carbon grains and carbon chains similar to those found in oil.
Stardust, an ultra-high vacuum machine built in the ERC Nanocosmos project (a Synergy project funded by the European Research Council), was specifically conceived to simulate, with a high level of control, the complex conditions of stardust formation and processing in the environment of evolved stars. In addition, the AROMA setup was built to analyse the molecular content of the samples synthesized by Stardust.
In the words of José Ángel Martín-Gago (Institute of Materials Science of Madrid, ICMM-CSIC, Spain), responsible for the Stardust instrument, “Mimicking the conditions of the envelope of an evolved star, laboratory experiments allow scientists to follow, step by step, the formation process of dust grains, from atoms to simple molecules and their growth to more complex clusters of molecules.”
For José Cernicharo (Institute of Fundamental Physics, IFF-CSIC, Spain), lead co-investigator of the project together with Martín-Gago and Christine Joblin (Institut de Recherche en Astrophysique et Planétologie, IRAP-CNRS, France), “That process is important because those grains of dust, which emerge from the final stages of the evolution of medium-sized stars like our Sun will provide the fundamental pieces needed for the birth of the planets and the main ingredients for the onset of life once injected into the interstellar medium.”
This is why it is essential to develop experiments combining laboratory astrophysics, surface science and astronomical observations to unveil the chemical routes that operate in the inner layers of the envelope of evolved stars.
The results obtained show the formation of amorphous carbon nanograins and aliphatic carbon clusters with traces of aromatic species and no fullerenes. This shows that the latter species cannot form effectively by gas-phase condensation at these temperatures in the zone of the evolved star where the dust is formed, a region that extends up to a few stellar radii.
Carbon dust analogues were produced in Stardust and analysed with several characterization techniques including Scanning Tunneling Microscopy and mass spectrometry with the AROMA setup. To produce them only gas carbon atoms and molecular hydrogen were used in a ratio close to that in the atmospheres of AGB stars.
The results showed two types of products: amorphous carbonaceous nanograins – the most abundant, considered to be the main component of carbonaceous star dust – and aliphatic carbon groups. But almost no aromatic molecules were found in the analysis.
According to Joblin, “Polycyclic aromatic hydrocarbons (PAHs) are widespread in massive star-forming regions and in carbon-rich protoplanetary and planetary nebulae. Large carbonaceous molecules like buckminsterfullerene C60 have also been detected in some of these environments. But it seems that they need different conditions to be formed”.
One possible pathway could be through thermal processing of aliphatic material on the surface of dust, which could take place as a result of the significant rise in the temperature of nanograins that occurs in highly UV-irradiated environments. Those results give us new insights into the chemistry of carbonaceous stardust seed formation and foster new observations in order to constrain the physical and chemical conditions in the inner shells of the envelops of evolved stars.
About the ERC
The European Research Council, set up by the
European Union in 2007, is the premier European funding organisation for
excellent frontier research. Every year it selects and funds the very
best, creative researchers of any nationality
and age to run projects based in Europe. The ERC has three grant
schemes for individual principal investigators – Starting Grants,
Consolidator Grants, and Advanced Grants – and Synergy Grants for small
groups of excellent researchers.
To date, the ERC has funded more than 9,000 top
researchers at various stages of their careers, and over 50,000
postdoctoral fellows, PhD students and other staff working in their
research teams. The ERC strives to attract top researchers
from anywhere in the world to come to Europe.
The ERC is led by an independent governing body,
the Scientific Council. The ERC current President is Professor
Jean-Pierre Bourguignon. The ERC has an annual budget of €2 billion for
the year 2019. The overall ERC budget from 2014 to
2020 is more than €13 billion, as part of the Horizon 2020 programme,
for which European Commissioner for Research, Innovation and Science
Carlos Moedas is currently responsible.
On June 7, 2019, a first paper on the GACELA (GAs CEll for Laboratory Astrophysics) experimental set-up is out at the “Astronomy & Astrophysics” journal (A&A, volume 626, A34, 2019).
More than 3 years have elapsed since the first designs were envisaged for this set-up. Finally, at the end of 2017, the chamber (see figure above) was delivered and successfully tested against leaks. On the other hand, the GACELA broad-band radio receivers (Q and W bands, 31.5–50 and 72–116.5 GHz, respectively) were successfully commissioned in the second semester of 2017 and interfaced with the GACELA set-up in February 2018. Several experimental runs were performed, showing high quality signal-to-noise ratio spectra of molecular species (CH3CN, CH3OH, CH4/N2, CH4/N2/CH3CN, etc).
As stated by the authors, GACELA has achieved an important milestone. It is the first time that we can observe the thermal emission of molecules with an instantaneous band width of 20 GHz in Q band and 3 × 20 GHz in W band for Laboratory Astrophysics. These rotational spectroscopy measurements are complemented by mass spectrometry and optical spectroscopy.
In summary, NANOCOSMOS has developed an elegant and fast-responding set-up, the GACELA, to provide high-resolution and high-sensitivity spectra of molecular species produced in cold plasmas or UV experiments.
This research was presented in the paper “Broad-band high-resolution rotational spectroscopy for laboratory astrophysics“, published in Astronomy and Astrophysics 626, A34 (29pp), 2019 June 7. The authors are: José Cernicharo (Instituto de Física Fundamental, IFF-CSIC), Juan D. Gallego (Centro de Desarrollos Tecnológicos, Observatorio de Yebes, IGN), José A. López-Pérez (CDT, OY, IGN), Félix Tercero (CDT, OY, IGN), Isabel Tanarro (Instituto de Estructura de la Materia, IEM-CSIC), Francisco Beltrán (CDT, OY, IGN), Pablo de Vicente (CDT, OY, IGN), Koen Lauwaet (Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC & IMDEA Nanociencia), Belén Alemán (ICMM-CSIC & IMDEA Materiales), Elena Moreno (IFF-CSIC), Víctor J. Herrero (IEM-CSIC), José L. Doménech (IEM-CSIC), Sandra I. Ramírez (Centro de Investigaciones Químicas, UAEM, Mexico), Celina Bermúdez (IFF-CSIC), Ramón J. Peláez (IEM-CSIC), María Patino-Esteban (CDT, OY, IGN), Isaac López-Fernández (CDT, OY, IGN), Sonia García-Álvaro (CDT, OY, IGN), Pablo García-Carreño (CDT, OY, IGN), Carlos Cabezas (IFF-CSIC), Inmaculada Malo (CDT, OY, IGN), Ricardo Amils (CDT, OY, IGN), Jesús Sobrado (Centro de Astrobiología, INTA-CSIC), Carmen Díez-González (CDT, OY, IGN), José M. Hernández (IFF-CSIC/CDT, OY, IGN), Belén Tercero (CDT, OY, IGN), Gonzalo Santoro (ICMM-CSIC), Lidia Martínez (ICMM-CSIC), Marcelo Castellanos (IFF-CSIC), Beatriz Vaquero-Jiménez (CDT, OY, IGN), Juan R. Pardo (IFF-CSIC), Laura Barbas (CDT, OY, IGN), José A. López-Fernández (CDT, OY, IGN), Beatriz Aja (Universidad de Cantabria), Arnulf Leuther (Fraunhofer Institut fur Angewandte Festkorperphysik, Germany), José A. Martín-Gago (ICMM-CSIC).
The GACELA experimental set-up is located at the Centro de Desarrollos Tecnológicos, Observatorio de Yebes, thanks to a bilateral agreement between CSIC and IGN for the development of the NANOCOSMOS project.
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 Nature Journal published yesterday a paper entitled “Compression and ablation of the photo-irradiated molecular cloud the Orion Bar”, led and with the participation of several members of our group.
One-arcsecond-resolution millimetre-wave images taken with ALMA enable the ‘skin’ of the Orion molecular cloud to be resolved. The stunning images reveal a fragmented ridge of high-density filamentary substructures, photoablative gas flows and instabilities that suggest that the cloud edge has been compressed by a high-pressure wave expanding into the molecular cloud. These results are in contrast to predictions from static equilibrium models and reveal a very dynamic UV-irradiated cloud edge.
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
The European Conference on Laboratory Astrophysics – Gas on the Rocks (ECLA2016) will be held at the CSIC headquarters in Madrid on November 21 – 25, 2016.
The conference will address the state of the art in laboratory astrophysics within the context of new astrophysical data and to improve communication and collaboration between astrophysicists, physicists and (geo) chemists. Hence, the conference structure will consist of invited talks presenting topics in astrophysics and planetary science and related laboratory astrophysics activities. Contributing talks will be selected to complement the topics from the astrophysical, laboratory, and theoretical/modeling points of view.