Origin of life can be traced before the birth of planet!
On March 13, 2024, a team of international astronomers using the NASA/ESA/CSA James Webb Space Telescope made a groundbreaking discovery. They found a variety of molecules, ranging from simple ones like methane to more complex compounds like acetic acid and ethanol, in early-stage protostars where planets have not yet formed. This finding has significant implications for our understanding of the origins of life in the universe.
The presence of complex organic molecules (COMs) in the solid phase in protostars was first predicted decades ago through laboratory experiments. However, it was not until now that these molecules have been individually identified and confirmed to be present in interstellar ices thanks to the unprecedented spectral resolution and sensitivity of Webb’s Mid-InfraRed Instrument (MIRI). The discovery was made as part of the JOYS+ (James Webb Observations of Young ProtoStars) program.
Some of the key COMs detected include acetaldehyde, ethanol (commonly known as alcohol), methyl formate, and likely acetic acid (the acid found in vinegar). These molecules were previously detected in the warm gas phase but are now believed to originate from sublimation – changing directly from a solid to a gas – of ices. This suggests that solid-phase chemical reactions on the surfaces of cold dust grains can build complex molecules.
This finding contributes to one of the long-standing questions in astrochemistry, said team leader Will Rocha from Leiden University. 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 dust grains play a crucial role in their formation.
The detection of COMs in ices also raises the possibility of these molecules being transported to planets at later stages in the evolution of the protostar. This is because icy COMs are more efficiently transported into planet-forming discs than gas from clouds. Therefore, these molecules could potentially be inherited by comets and asteroids, which may then collide with planets in formation and provide the necessary ingredients for life to flourish.
In addition to COMs, the team also detected simpler molecules such as methane, formic acid (which makes the sting of ants painful), sulphur dioxide, and formaldehyde. The presence of sulphur dioxide is particularly interesting as it allows scientists to investigate the sulphur budget available in protostars. It is also of prebiotic interest as research suggests that sulphur-containing compounds played a crucial role in driving metabolic reactions on Earth.
The team also made another intriguing discovery – negative ions were detected. These ions are crucial components of salts that play a vital role in developing further chemical complexity.
The James Webb Space Telescope’s Early Release Science Ice Age program had previously discovered diverse ices in molecular clouds. However, this new finding takes us one step closer to understanding the origins of complex organic molecules and their role in the development of life.
Lead scientist Will Rocha shared his excitement about this discovery, saying, The detection of these complex organic molecules not only contributes to our understanding of astrochemistry but also opens up new possibilities for exploring the origins of life.
This groundbreaking discovery would not have been possible without the contributions of Harold Linnartz from Leiden University’s Laboratory for Astrophysics, who coordinated the measurements used in this study. Ewine van Dishoeck from Leiden University and one of the coordinators for JOYS+ expressed her gratitude towards Linnartz, saying, Harold was particularly happy that lab work could play an important role in the assignment of COMs as it has been a long time getting here.
The team’s findings have been published in the scientific journal Nature. With the James Webb Space Telescope’s advanced capabilities, we can expect more groundbreaking discoveries and a deeper understanding of our universe in the years to come.
For more information on this discovery and other updates from the James Webb Space Telescope, visit their website at https://esawebb.org/news/weic2409/?lang.
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