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-atoms4-atoms5-atoms6-atoms7 or more
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-atoms3-atoms4-atoms5-atoms6-atoms7 or more
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 Cloudcredit ESO.