Discovery of Molecular Species in Space

NANOCOSMOS has performed a systematic work to identify “unknown” gas-phase species in circumstellar envelopes and interstellar molecular clouds. These species are the carriers of the so-called U-lines or unidentified features. Currently, the team has found more than 1,000 U-lines formed in the photosphere surroundings of the AGB carbon star IRC+10216. We are progressing in the identification of these carriers to complete a spectral catalogue and merge this catalogue into the MADEX radiative transfer code.

Definitely, NANOCOSMOS is characterizing different dust formation places in Space through the observations of molecular lines. So far, the team has already discovered 10 new molecular species in the inner regions of the envelope of IRC+10216 and 32 more in the interstellar medium until April 2021. These findings include the detection for the first time in Space of three new pure hydrocarbon cycles: c-C₃HCCH (ethynyl cyclopropenylidene), c-C₅H₆ (cyclopentadiene), and the polycyclic aromatic hydrocarbon (PAH) c-C₉H₈ (indene). These hydrocarbons could be one of the keystones to elucidate bottom-up mechanisms in the formation of the first aromatic ring in cold molecular clouds, from which large PAHs may grow.

Our discoveries amount to approximately a 20% of known molecules in Space.

The team has made a joint effort on the following objects. IRC+10216 is the archetypal AGB carbon rich star, given its proximity ~ 130 pc, and unpaired molecular richness with more than 80 molecular species prior to NANOCOSMOS. R Leo is one of the closest AGB oxygen rich stars, at a distance of ~ 80 pc. Multi-wavelength molecular observations of this star show no detection of CO₂ despite predictions from chemical models. Y CVn is a carbon rich semi-regular star at ~ 310 pc from the Earth. Its circumnuclear envelope has not been explored in detail mostly due to the lack of sensitive observations. Finally, the Taurus Molecular Cloud -1 or TMC-1, is a cold dark molecular cloud. It presents an interesting carbon-rich chemistry that leads to the formation of long neutral carbon-chain radicals and their anions, as well as cyanopolyynes, and protonated species of abundant large carbon chains.

This menu splits our stunning discoveries into the following entries:

Yebes 40 m radio telescope new broad band receivers and complementary observations with the IRAM 30 m radio telescope. Multiple discoveries of molecular species in IRC+10216 and TMC-1. Further contraints on chemical models.
High-resolution observations of the inner dust formation zone in IRC+10216 with the ALMA radio interferometer. Our analysis is ongoing.
ALMA and IRAM 30m observations of the circumstellar envelopes of AGB stars, cold dark clouds and prestellar cores. These observations include two IRAM molecular surveys of 40 AGB stars. Several discoveries of molecular species in IRC+10216 and in other objects.
High spectral resolution Infrared observations of R Leo with the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA), IRC+10216 with the NASA Infrared Telescope Facility (IRTF) and Y CVn with both observatories.

The team is currently submitting new exciting results from the NANOCOSMOS legacy molecular survey of evolved stars with the Yebes 40m radio telescope. Also, we are interpreting new challenging results from ALMA high resolution observations of IRC+10216 that will boost our previous observations of this source. The best for NANOCOSMOS is yet to come!

IRC+10216: new molecules inventory

3-atoms	4-atoms	5-atoms	6-atoms	7 or more
Si₂C	PH₃	MgC₃N	SiH₃CN	SiH₃CH₃
CaNC	MgCCH		C₄H₂
	NCCP		MgC₄H

Table: Red labels (Yebes 40m); Black (IRAM/ALMA); Green (IRTF/TEXES). See the internal menu pages for more ongoing information on these molecular species. Left: figure thanks to Dr. J. P. Fonfría.

Interstellar Medium: new molecules inventory

2-atoms	3-atoms	4-atoms	5-atoms	6-atoms	7 or more
NS⁺	NCO	HCCO	HC₃O⁺	CH₂CCH	HC₄NC
	HCS	CNCN	HDCCN	H₂CCCS	HCCCH₂CN
	HSC	HCCN	H₂CCS	HC₄N	CH₂CCHCN
	NCS	HCCS	C₄S	C₅S	CH₂CHCCH
		C₃N^_	HC₃S⁺	CH₃CO⁺	HC₅NH⁺
			H₂NCO⁺	C₅N^_	H₂CCCHCCH
					CH₃CH₂CN
					c-C₃HCCH
					c-C₅H₆
					c-C₉H₈ (PAH)

Table: Red labels (Yebes 40m); Black (IRAM/ALMA). See the internal menu pages for more information on these molecular species. Left image: Taurus Molecular Cloud – credit ESO.

OUTSTANDING RESULTS

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:

Stardust machine.
AROMA (Astrochemistry Research of Organics with Molecular Analyzer).
PIRENEA 2 (improvement of the “Ion Trap for the Research and Study of New Astrochemical Species”).
GACELA (Gas Cell for Laboratory Astrophysics).
Nanocosmos millimeter broad band receivers for GACELA and the 40m Yebes radio telescope.

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.

Carbon grains around evolved stars

2019/10/22 / Natalia Ruiz

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 astronomers will map Orion with SOFIA

2015/10/26 / Marcelo Castellanos

A legacy program to map the far-IR fine structure line of C⁺ at 158 microns with the Stratospheric Observatory for Infrared Astronomy (SOFIA) has been recently awarded to a small international team led by Prof. Tielens (Leiden Observatory, The Netherlands) and including 3 members of the NANOCOSMOS project, Dr. J. R. Goicoechea (ICMM-CSIC), Dr. O. Berné (IRAP, CNRS) and Prof. J. Cernicharo (ICMM-CSIC). The observing time to map the Orion molecular cloud will be more than 50 hours, which means several flights on board SOFIA!!

[CII] 158μm emission image taken by Herschel with the locations of famous regions in the cloud identified (Goicoechea et al. 2015). SOFIA will map an area 20 times larger than the region covered by Herschel.

The ionized carbon emission dominates the gas cooling of the low density interstellar medium and it is the brightest emission line in the IR spectrum of galaxies. In the next 2 years, astronomers will use the instrument upGREAT flying on board SOFIA to map an area of more than 20 times the central region of Orion recently observed with the Herschel Space Telescope (Goicoechea et al. 2015, ApJ, 812, 75, see the publications section). This project will allow to uniquely determine the use of the C⁺ line as a star formation rate indicator, derive the amount of molecular cloud mass not measured by CO (so-called “CO-dark” gas), and semi-empirically determine the photo-electric heating efficiency on Polycyclic Aromatic Hydrocarbons (PAHs) and interstellar dust grains.

The Stratospheric Observatory For Infrared Astronomy (SOFIA) is a joint project between NASA and the German Aerospace Center (DLR) consisting of a custom-modified Boeing 747SP aircraft with an effective aperture of 2.5 m mounted in an open cavity towards the tail of the aircraft.

SOFIA air-to-air over the Sierra Nevada Mountains (Credit: NASA, USRA (Universities Space Research Association), and L-3 Communications Integrated Systems/Jim Ross)

Nick Cox at The Physics of Evolved Stars (POE2015) conference

2015/06/18 / Marcelo Castellanos

nanocosmos_general_poster_final

The Nanocosmos project was presented at The Physics of Evolved Stars (POE2015) conference by Nanocosmos astronomer Dr. Nick Cox on behalf of the three PIs. This international meeting, held from 8-12 June in Nice, France, was organised to honour Dr. Olivier Chesneau (Observatoire de Nice) who passed away in 2014. Presentations at the meeting covered the broad range of scientific interests of Olivier: from AGB stars, Planetary Nebulae, R CrB stars, Novae, Symbiotic systems, and many more. Many presentations at this meeting centred on understanding the formation and presence of dust and molecules in circumstellar environments of both low- and high-mass evolved stellar systems, topics of particular interest to Nanocosmos researchers.