An international team of astronomers using the
“This finding contributes to one of the long-standing questions in astrochemistry,” said team leader Will Rocha of Leiden University in the Netherlands. “What is the origin of COMs in space? Are they made in the gas phase or in ices? The detection of COMs in ices suggests that solid-phase chemical reactions on the surfaces of cold dust grains can build complex kinds of molecules.”
Significance of Solid-Phase COMs
As several COMs, including those detected in the solid phase in this research, were previously detected in the warm gas phase, it is now believed that they originate from the sublimation of ices. Sublimation is to change directly from a solid to a gas without becoming a liquid. Therefore, detecting COMs in ices makes astronomers hopeful about developing an improved understanding of the origins of other even larger molecules in space.
Harold Linnartz[2] led the Laboratory for Astrophysics in Leiden over many years and coordinated the measurements of the data used in this study. Ewine van Dishoeck of Leiden University, one of the coordinators of the JOYS+ program, shared, “Harold was particularly happy that in the COM assignments lab work could play an important role as it has been a long time getting here.”
Scientists are also keen to explore to what extent these COMs are transported to planets at much later stages in the evolution of the protostar. COMs in ices are transported more efficiently into planet-forming discs than gas from clouds. These icy COMs can therefore be inherited by comets and asteroids which in turn may collide with planets in formation. In that scenario COMs can be delivered to those planets, potentially providing the ingredients for life to flourish.
Broader Astrochemical Context
The science team also detected simpler molecules, including methane, formic acid (which makes the sting of ants painful), sulfur dioxide, and formaldehyde. Sulphur dioxide in particular allows the team to investigate the sulphur budget available in protostars. In addition, it is of prebiotic interest because existing research suggests that sulfur-containing compounds played an important role in driving metabolic reactions on the primitive Earth. Negative ions were also detected;[3] they form part of salts that are crucial for developing further chemical complexity at higher temperatures. This indicates that the ices may be much more complex and require further research.
Of particular interest is that one of the sources investigated, IRAS 2A, is characterized as a low-mass protostar. IRAS 2A may therefore have similarities with the primordial stages of our own Solar System. If that is the case, the chemical recent work by Pooneh Nazari of Leiden Observatory also raises astronomers’ hopes for finding more complexity in ices, following the tentative detections of methyl cyanide and ethyl cyanide from Webb NIRSpec data. Nazari says, “It is impressive how Webb now allows us to further probe the ice chemistry down to the level of cyanides, important ingredients in prebiotic chemistry.”
Notes
- A molecule is a particle made up of two or more atoms that are held together by chemical bonds. A complex organic molecule is a molecule with multiple carbon atoms.
- These results are dedicated to team member Professor Harold Linnartz, who unexpectedly passed away in December 2023, shortly after the acceptance of this paper. Linnartz made significant contributions to the study of gaseous and icy molecules in space. He was the Director of the Leiden Laboratory for Astrophysics and many of the ice-phase spectra of simple and complex molecules used in this research were collected by students under his supervision. Linnartz was thrilled with the quality of the Webb data and the significance of these results for astrochemistry.
- An ion is an DOI: 10.1051/0004-6361/202348427
More Information
These observations were taken as part of the JOYS+ (James Webb Observations of Young ProtoStars) program, coordinated by Ewine van Dishoeck of Leiden University in the Netherlands, and Michael Ressler of NASA’s Jet Propulsion Laboratory. The research was led by Will Rocha Leiden University. The cyanate studies were made as part of the IPA (Investigating Protostellar Accretion) program, coordinated by Tom Megeath of the University of Toledo.
Webb is the largest, most powerful telescope ever launched into space. Under an international collaboration agreement, ESA provided the telescope’s launch service, using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations for the Webb mission and for the procurement of the launch service by Arianespace. ESA also provided the workhorse spectrograph NIRSpec and 50% of the mid-infrared instrument MIRI, which was designed and built by a consortium of nationally funded European Institutes (The MIRI European Consortium) in partnership with