Discovery of alcohol molecule in interstellar space could change understanding of life’s origin

Findings could help shed more light on chemical composition of comets and other bodies in Solar system

Scientists have detected an alcohol molecule commonly used in hand sanitizers for the first time in interstellar space, an advance that sheds more light on the formation of organic molecules in the Milky Way galaxy.

The research, published recently in two studies in the journal Astronomy Astrophysics, identified isopropyl alcohol in a “delivery room” of stars, the massive star-forming region Sagittarius B2, located near the centre of the galaxy.

Scientists, including those from the Max Planck Institute for Radio Astronomy in Germany, made the findings using data from the ALMA telescope in the Chilean Atacama Desert.

Over the last five decades, researchers seeking to identify new molecules in space have so far discovered 276 specific molecule types.

The new study is the first to identify the molecule iso-propanol – the largest alcohol detected so far in interstellar space – demonstrating the increasing complexity of one of the most abundant classes of molecule found in space.

“We’re discovering molecules that are more and more complicated at the very early stages of star formation,” Rob Garrod, co-author of one of the studies from the University of Virginia in the US, said.

“Increasingly, we’re looking at a situation where life is potentially being given a head start by the chemistry happening very early on in space, before even a planet is formed,” Dr Garrod explained.

The new studies sought to understand how organic molecules form in the interstellar medium, in particular in regions where new stars are born, and how complex these molecules can be.

Scientists hope the findings could help establish connections to the chemical composition of bodies in the Solar system such as comets.

The new discovery was made possible by observing a specific star-forming region called Sagittarius B2 (SgrB2) in the galaxy where many molecules have already been detected.

While the microwave-wavelength energy emission from molecules floating around in Sgr B2 can be recognised back on Earth, scientists say these patterns can be weak and difficult to distinguish from each other.

One of the main difficulties in identifying organic molecules in starforming regions is what researchers call “spectral confusion.”

Molecules emit radiation at specific frequencies called its spectral “fingerprint” and this is known from laboratory measurements.

The bigger a molecule, the more spectral lines at different frequencies it produces, scientists say.

In a source like Sgr B2, there are so many molecules contributing to the observed radiation that their spectra overlap, making it difficult to disentangle their unique fingerprints.

But thanks to the high sensitivity and resolution of ALMA, they say it has been possible over the last decade to go beyond what could be achieved earlier.

“Our group began to investigate the chemical composition of Sgr B2 more than 15 years ago. These observations were successful and led in particular to the first interstellar detection of several organic molecules, among many other results,” Arnaud Belloche from the Max Planck Institute for Radio Astronomy, said.

Propanol is an alcohol molecule containing carbon, hydrogen and oxygen atoms, existing in two forms, or isomers, depending on which carbon atom the hydroxyl functional group (-OH) is attached to.

One of these forms is normal propanol, with the -OH bound to a terminal carbon atom of the chain, and the other is iso-propanol, with the hydroxyl bound to the central carbon atom in the chain.

Researchers identified both isomers of propanol in Sgr B2 based on the ALMA dataset.

The newly-published studies are part of a long-standing effort to probe the chemical composition of sites in Sgr B2, where new stars are being formed.

Scientists hope to understand from this ongoing work the chemical processes at work during star formation.

“The star formation process is associated not just with forming very complex molecules, but it’s also important for heating them up, releasing them from the dust grains and into the gas phase where we can actually detect them,” Dr Garrod explained.

“Our theory group at UVA produces computational models of all of that solid phase and gas phase chemistry, including the release of those molecules into the gas, in order to explain the actual abundances we detect with the radio telescopes,” he added.

Researchers say there are still many unidentified spectral lines in the ALMA spectrum of Sgr B2.

In future studies, scientists hope to fine-tune the ALMA instrumentation and reduce the spectral confusion even further to allow the identification of additional organic molecules in this spectacular source.