High-resolution Infrared Observations

High spectral resolution infrared observations of circumstellar envelopes – CSEs – in AGB stars are essential to study important molecular species with no permanent dipole moment (e.g. H2, O2, CO2, SiH4, C2H4). This lack makes them undetectable in the millimeter range due to the absence of rotational transitions. Hence, the best possible observation of these molecules is through its vibration–rotation lines in the mid infrared range.

These observations are vital to study the amount of ejected matter in the pulsation phase and determine the chemical interactions between the ejected molecules in the CSEs. These studies help improve the underlying assumptions of currently available chemical models.

Therefore, we observed the carbon-rich star IRC+10216 with the Texas Echelon-cross-Echelle Spectrograph (TEXES) on the 3 m Infrared Telescope Facility (IRTF). We carried out observations of the oxygen rich star R Leo with the Stratospheric Observatory for Infrared Astronomy (SOFIA) with the high spectral resolution Echelon-cross-Echelle Spectrograph (EXES). Finally, we used both SOFIA/EXES and IRTF/TEXES to observe the carbon rich semi-regular star Y CVn.

Summary of oustanding results with the NANOCOSMOS high-resolution infrared observations of CSEs in AGB stars

Multi-frequency high spectral resolution observations of HCN toward the circumstellar envelope of Y CVn (J. P. Fonfría et al., A&A, submitted)

  • Analysis and Identification of 130 lines of HCN and H13CN with either P-Cygni profiles or pure absorption profiles
  • Dust grains could be mostly made of silicon carbide SiC in the inner layers of the CSE (~ 3.5 stellar radii) and of amorphous carbon in the outer envelope (up to 200 stellar radii)
  • The observed mid-IR lines are broader than expected due to possible high velocity matter ejections or photospheric movements related to stellar pulsation or convection.
  • HCN rotational and vibrational temperatures are out of local thermodynamics equilibrium so collisions do not play any role in the gas thermalization


Detection of infrared fluorescence of carbon dioxide in R Leonis with SOFIA/EXES (J. P. Fonfría et al., A&A, 11/2020)

  • CO2 (≃240 emission lines in the range 12.8−14.3 μm) New detection in R Leo
  • The observed CO2 lines can be grouped into three different populations, (warm, hot, and very hot), with approximate temperatures of 550, 1150, and 1600 K
  • The CO2 emitting regions at 1600, 1150, and 550 K are located at 2.2, 3.5, and 10 stellar radii from the center of R Leo
  • We need a systematic study of the CO2 emission in O-rich stars to understand how this molecule forms and the possible dependence of the column density on the mass-loss rate


Carbon Chemistry in IRC+10216: Infrared Detection of Diacetylene (J. P. Fonfría et al., ApJ, 01/2018)

  • C4H2 (24 absorption features in the range 8.0 to 8.1 μm) First detection in IRC+10216
  • The major emission of C4H2 arises in the dust formation zone at radii lower than 20 stellar radii (50 Astronomical Units) from the center of IRC+10216
  • Our photochemical models underestimate the observed C4H2 abundance. This finding could imply that the molecules in the envelope are photodissociated in shells closer to the star than is commonly assumed


The Abundance of C2H4 in the Circumstellar Envelope of IRC+10216 (J. P. Fonfría et al., ApJ, 01/2017)

  • C2H4 (80 ro-vibrational features in absorption) Part of the emission arises in the inner dust formation zone contrary to previous findings
  • Part of the emission of acetylene arises in the dust formation zone at radii between 14 and 28 stellar radii from the center of IRC+10216, with no evidence of C2H4 closer to the star. Previous findings supposed all C2H4 arises in the far outer envelopes.
  • Our photochemical models underestimate the observed C2H4 terminal abundance by a factor of 4. We estimate that a fraction of the acetylene gas-phase could condense onto the dust grains around 20 stellar radii. this fact could affect the chemistry evolution of the envelope

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).

    Carbon grains around evolved stars

    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.

    Chemical complexity

    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.

    NANOCOSMOS at the Guillermo Haro School on Molecular Astrophysics (Puebla, Mexico)

    Prof. José Cernicharo has been awarded with the Guillermo Haro Visiting Professorship 2016 at the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE, posterGH16Puebla, Mexico). Following this award, INAOE has organized the Guillermo Haro School on Molecular Astrophysics (October 11 – 21, 2016). Several NANOCOSMOS scientists (Asunción Fuente from CNIG-IGN, Nuria Marcelino, José Pablo Fonfría and Luis Velilla from ICMM-CSIC) will give lectures on the following topics:

    • Molecular Astrophysics, Spectroscopy, Chemistry in the ISM (José Cernicharo)
    • Physical and chemical processes in the ISM, Protoplanetary disks (Asunción Fuente)
    • Observational methods and interpretation (Nuria Marcelino)
    • Molecular excitation and radiative transfer, Circumstellar medium (José Pablo Fonfría)
    • Chemistry in the circumstellar medium, atmospheric  effects and calibration (Luis Velilla)

    José Cernicharo will give a public talk in Puebla downtown on Thursday 13: “Moléculas en el espacio: Astroquímica”.

    ECLA 2016 – webpage open

    Ecla2016-1125x510

    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.

    www.ecla2016.com

    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

    NANOCOSMOS will organize the ECLA2016 – Gas on the Rocks conference

    Stardustiram_PdV

    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.

    More info here

     

    NANOCOSMOS at the recent ALMA / Herschel Archival Workshop (Garching, Germany)

    alma_herschel_low_resFour NANOCOSMOS researchers gave their presentations at the ALMA/Herschel Archival Workshop held in Garching (Germany) at the ESO headquarters in April 15 -17, 2015. José Cernicharo (NANOCOSMOS Corresponding P.I.) talked about the synergies between the ALMA high resolution observations in the innermost zones of star-forming regions, AGB, post-AGBs stars and extragalactic objects and those of Herschel´s archive submillimeter and far-IR observations. Our postdoctoral researchers, Marcelino Agúndez, Guillermo Quintana-Lacaci and Belén Tercero talked about the following topics: Continue reading →

    NANOCOSMOS workshops/meetings

    2017

    NANOCOSMOS Interstellar Dust Meeting

    Date: 12 – 13 June 2017

    Place: Université Paul Sabatier (Toulouse, France)

    Key dates: 

    Abstract submission deadline: April 30th, 2017

    Registration deadline: May 14th, 2017

    Webpage: https://epolm3-nanocosm.sciencesconf.org/

    2016

    European Conference on Laboratory AstrophysicsGas on the Rocks (ECLA2016)

    Outcome of the conference: See “A summary of the ECLA2016” link

    November 21 – 25, 2016 (CSIC Headquarters, Madrid, Spain)

    Webpage: ECLA2016

    FIRST ANNOUNCEMENT

    Key dates:
    Second announcement:  February 1st, 2016 (opening of the conference web page).
    Deadline for abstract submission: June 15, 2016
    Deadline for early registration: July 15, 2016
    Deadline for information participants about selected contributing talks: June 30, 2016
    Final program: July 15, 2016
    Last announcement with final details: November 1st, 2016

    Motivation:

    Over the last decade, European research activities in the field of laboratory astrophysics have experienced an impressive increase in their potential to address astrophysical problems, in particular by providing essential information on the physical and chemical processes leading to chemical complexity in space resulting in star and planet formation. These activities have been motivated by the interpretation of astronomical observations obtained with single dish telescopes and short baseline interferometers. The wealth of data obtained with ALMA, space facilities (Herschel, Spitzer, Rosetta, the coming JWST, E-ELT), and other ground based observatories (VLTI, NOEMA, …), require new methodologies for the astrophysical modeling that will lead to new challenges for laboratory astrophysics.

    This conference aims to address the state of the art in laboratory astrophysics within the context of these 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.

    The astrophysical areas that will be addressed are:

    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
    Chemical fingerprints of star formation
    The late stages of star evolution: dust formation
    Supernovae and shocks: high-energy processing of matter

    The conference will cover studies in many fields such as spectroscopy, analytical (geo) chemistry, reactivity, nanoscience, and quantum chemistry, pertaining to different matter components (gas, plasma, PAHs, ices, dust, solid surfaces, …).

    SOC composition
    Jose Cernicharo (chair). ICMM-CSIC, Madrid, Spain
    Christine Joblin (co-chair). IRAP, Univ. Paul Sabatier/CNRS, Toulouse, France
    Isabel Tanarro. IEM-CSIC, Madrid, Spain
    Jose Angel Martín Gago. ICMM-CSIC, Madrid, Spain
    Karine Demyk. IRAP, Univ. Paul Sabatier/CNRS, Toulouse, France
    Jean-Hugues Fillion. LERMA, UPCM Univ.  Paris 06, & Obs. Paris, France
    Maria Elisabetta Palumbo. INAF-Catania Astrophysical Obs., Italy
    André Canosa. IPR, Univ. Rennes 1/CNRS, France
    Harold Linnartz. Leiden Obs., Univ. of Leiden, The Netherlands
    Liv Hornekaer. iNANO, Aarhus Univ., Danemark
    Peter Sarre. School of Chemistry, Nottingham Univ., UK
    Stephan Schlemmer. Phys. Inst., Univ. Koln, Germany
    Jonathan Tennyson. Univ. College London, UK
    Yves Marrochi. CRPG-CNRS, Nancy, France
    Guillermo Muñoz Caro. CAB, INTA-CSIC, Madrid, Spain

    LOC composition
    Isabel Tanarro (Chair). IEM-CSIC, Madrid, Spain
    Belén Maté. IEM-CSIC, Madrid, Spain
    Víctor J. Herrero. IEM-CSIC, Madrid, Spain
    José Luis Doménech. IEM-CSIC, Madrid, Spain
    Ángel González-Valdenebro. IEM-CSIC, Madrid, Spain
    Marcelo Castellanos (co-chair). ICMM-CSIC, Madrid, Spain
    Belén Tercero.  ICMM-CSIC, Madrid, Spain
    Juan Ramón Pardo. ICMM-CSIC, Madrid, Spain
    Juan Antonio Corbalán. ICMM-CSIC, Madrid, Spain
    Natalia Ruiz-Zelmanovich. ICMM-CSIC, Madrid, Spain

    The project

    idea

    Cosmic dust is made in evolved stars. However, the processes involved in the formation and evolution of dust remain so far unknown. NANOCOSMOS will take advantage of the new observational capabilities (increased angular resolution) of the Atacama Large Millimeter/submillimeter Array (ALMA) to unveil the physical and chemical conditions in the dust formation zone of evolved stars. These observations in combination with novel top-level ultra-high vacuum experiments and astrophysical modelling will provide a cutting-edge view of cosmic dust.