Astronomers have harnessed the power the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to detect methyl isocyanate — a chemical building block of life — in the warm, dense inner regions of the cocoon of dust and gas around solar-type protostars in the multiple system IRAS 16293-2422.
This image shows a region of star formation where methyl isocyanate was found. The insert shows the molecular structure of this chemical. Image credit: L. Calcada / ESO / Digitized Sky Survey 2.
Understanding the origin of life is one of the main challenges of modern science. It is believed that some basic prebiotic chemistry could have developed in space, likely transferring prebiotic molecules to the Solar Nebula and later on to Earth.
Methyl isocyanate (CH3NCO) is the simplest isocyanate, which along formamide (NH2CHO) contains C, N and O atoms, and could play a key role in the synthesis of amino acid chains known as peptides.
Interstellar methyl isocyanate was first detected in Sagittarius B2(N), the hot core of a giant molecular cloud near the Galactic center, in 2015.
Now, two international groups of astronomers have detected, for the first time, methyl isocyanate in solar-type protostars, the kind from which our Sun and the Solar System formed.
“Our findings indicate that the key ingredients for the origin of life could have been produced at an early stage of the Solar System,” said Dr. David Quénard, from Queen Mary University of London.
“This star system seems to keep on giving! Following the discovery of sugars, we’ve now found methyl isocyanate,” said Leiden Observatory astronomer Dr. Niels Ligterink and University College London researcher Dr. Audrey Coutens.
“This family of organic molecules is involved in the synthesis of peptides and amino acids, which, in the form of proteins, are the biological basis for life as we know it.”
IRAS 16293-2422 is located in a large star-forming region called Rho Ophiuchi in the constellation of Ophiuchus, at a distance of 391 light-years from Earth.
The system is composed of two infant stars, IRAS 16293-2422A and IRAS 16293-2422B, whose masses are about 0.5 solar masses.
The new results from ALMA show that methyl isocyanate gas surrounds each of these stars.
“We are particularly excited about the result because these protostars are very similar to the Sun at the beginning of its lifetime, with the sort of conditions that are well suited for Earth-sized planets to form,” said Dr. Rafael Martín-Doménech of the Centro de Astrobiología in Madrid, Spain, and Dr. Víctor Rivilla of the INAF-Osservatorio Astrofisico di Arcetri in Florence, Italy.
“By finding prebiotic molecules in this study, we may now have another piece of the puzzle in understanding how life came about on our planet.”
“Besides detecting molecules we also want to understand how they are formed,” Dr. Ligterink said.
“Our laboratory experiments show that methyl isocyanate can indeed be produced on icy particles under very cold conditions that are similar to those in interstellar space. This implies that this molecule — and thus the basis for peptide bonds — is indeed likely to be present near most new young solar-type stars.”
The findings are published in two papers in the Monthly Notices of the Royal Astronomical Society.
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N.F.W. Ligterink et al. 2017. The ALMA-PILS survey: detection of CH3NCO towards the low-mass protostar IRAS 16293−2422 and laboratory constraints on its formation. Mon Not R Astron Soc 469 (2): 2219-2229; doi: 10.1093/mnras/stx890
R. Martín-Doménech et al. 2017. Detection of methyl isocyanate (CH3NCO) in a solar-type protostar. Mon Not R Astron Soc 469 (2): 2230-2234; doi: 10.1093/mnras/stx915
