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In a development believed to shed light on the building blocks of life, an international team of scientists, including Prof Wendy Brown from the University of Sussex, has discovered diverse ices in the darkest, coldest regions of space so-far measured, which are around 500 light years from Earth.

The discovery within a molecular cloud was made by scientists from the IceAge project, an international consortium of academics using the James Webb Space Telescope (JWST), to observe the building blocks of life.  The JWST is a collaboration between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).

This result allows astronomers to examine the simple icy molecules that will be incorporated into future exoplanets – which are the planets which orbit stars outside of our solar system – while opening a new window on the origin of more complex molecules that are the first step in the creation of the building blocks of life.  The study offers the first proof that complex molecules form in the ice deep within molecular clouds before stars themselves are born.

The ices were detected and measured by studying how starlight from beyond the molecular cloud was absorbed by icy molecules at specific infrared wavelengths visible to the JWST. This process leaves behind chemical fingerprints known as absorption spectra which can be compared with laboratory data to identify which ices are present in the molecular cloud – which is where Professor Brown’s expertise comes in.

In this study, the team targeted ices buried in a particularly cold, dense and difficult to investigate region of the Chameleon I molecular cloud, a region roughly 500 light-years from Earth, which is currently in the process of forming dozens of young stars.

Professor Wendy Brown from the University of Sussex is part of the project. Her role is to undertake laboratory investigations, for example, recording laboratory spectra – which act as fingerprints for molecules – for model ices to look for signatures within the ices that can help to assign the spectra recorded with JWST.

Prof Brown, Head of the Department of Chemistry within the School of Life Sciences at the University of Sussex, said:

“We use the JWST to look at ices and to observe the ice mantle composition, structure and physical and chemical evolution, which helps us to understand how stars and planets were formed.

“In my role I undertake experiments in the laboratory to record spectra of model ices containing a range of components such as water and organic molecules. These spectra help us to understand the composition of the ices observed in space by the JWST.

“It’s an incredibly exciting project as we can now more clearly observe images and spectra that allow us to identify the molecules found on icy dust grains in space. This will help us to have a better understanding of the building blocks of life, where they come from and how they were made.”

Now an in-depth inventory of the deepest, coldest ices measured to date in a molecular cloud has been announced by the international team of astronomers using the JWST. In addition to simple ices like water, the team was able to identify frozen forms of a wide range of molecules, from carbon dioxide, ammonia, and methane, to the complex organic molecule methanol. This is the most comprehensive census to date of the icy ingredients available to make future generations of stars and planets, before they are heated during the formation of young stars.

In addition to the identified molecules, the team found evidence for prebiotic molecules more complex than methanol in these dense cloud ices, and, although they didn't definitively attribute these signals to specific molecules, this proves for the first time that complex molecules form in the icy depths of molecular clouds before stars are born.

Professor Brown is working closely with the members of the consortium led by Dr Melissa McClure, an astronomer at Leiden Observatory who is the principal investigator of the observing program and lead author of the paper describing this result.

Dr McClure, Assistant Professor at Leiden Observatory, said:

“Our results provide insights into the initial, dark chemistry stage of the formation of ice on the interstellar dust grains that will grow into the centimetre-sized pebbles from which planets form in discs. These observations open a new window on the formation pathways for the simple and complex molecules that are needed to make the building blocks of life.”

“This is just the first in a series of spectral snapshots that we will obtain to see how the ices evolve from their initial synthesis to the comet-forming regions of protoplanetary discs. This will tell us which mixture of ices — and therefore which elements — can eventually be delivered to the surfaces of terrestrial exoplanets or incorporated into the atmospheres of giant gas or ice planets.”

This research forms part of the IceAge project, one of Webb's 13 Early Release Science' programmes.

This news is the latest development for the University of Sussex’s stellar astronomy experts. In the autumn, Dr Rosemary Coogan, a recent graduate of the University of Sussex was announced as one of the European Space Agency’s (ESA) new astronauts. Dr Coogan is a newly appointed ‘career astronaut’ for the ESA, following her studies at Sussex between 2015 and 2019, when she completed a Masters and PhD which focused on super-massive black holes and the formation of stars.

And last summer, Dr Stephen Wilkins was part of the team to analyse, and shed light on, the very first images from the James Webb Space Telescope, having been involved with the telescope since before its launch. 

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