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Cheers! NASA’s Webb Finds Ethanol, Other Icy Ingredients for Worlds

An image of a region of a molecular cloud. The orange cloud is dense and bright close to the top of the image, like rolling clouds, and grows darker and more wispy toward the bottom and in the top corner. One bright star with six short diffraction spikes and several dimmer stars are visible as light spots among the clouds.

Webb MIRI image of a region near the protostar known as IRAS 23385. IRAS 23385 and IRAS 2a.

Credits: NASA, ESA, CSA, W. Rocha (Leiden University)

Editor's Note: This article was updated March 13, 2024, to clarify the likelihood that chemicals found around IRAS 2A were present in the first stages of development of our solar system.

What do margaritas, vinegar, and ant stings have in common? They contain chemical ingredients that NASA’s James Webb Space Telescope has identified surrounding two young protostars known as IRAS 2A and IRAS 23385. Although planets are not yet forming around those stars, these and other molecules detected there by Webb represent key ingredients for making potentially habitable worlds.

An international team of astronomers used Webb’s MIRI (Mid-Infrared Instrument) to identify a variety of icy compounds made up of complex organic molecules like ethanol (alcohol) and likely acetic acid (an ingredient in vinegar). This work builds on previous Webb detections of diverse ices in a cold, dark molecular cloud.

Image A: Parallel Field to Protostar IRAS 23385 (MIRI Image)

This image at a wavelength of 15 microns was taken by MIRI (the Mid-Infrared Instrument) on NASA’s James Webb Space Telescope, of a region near the protostar known as IRAS 23385. IRAS 23385 and IRAS 2A (not visible in this image) were targets for a recent research effort by an international team of astronomers that used Webb to discover that the key ingredients for making potentially habitable worlds are present in early-stage protostars, where planets have not yet formed.

NASA, ESA, CSA, W. Rocha (Leiden University)

What is the origin of complex organic molecules (COMs) ?

“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 complex organic molecules, or 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.”

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 improved understanding of the origins of other, even larger molecules in space.

Scientists are also keen to explore to what extent these COMs are transported to planets at much later stages of protostellar evolution. COMs in cold ices are thought to be easier to transport from molecular clouds to planet-forming disks than warm, gaseous molecules. These icy COMs can therefore be incorporated into comets and asteroids, which in turn may collide with forming planets, delivering the ingredients for life to possibly flourish.

The science team also detected simpler molecules, including formic acid (which causes the burning sensation of an ant sting), methane, formaldehyde, and sulfur dioxide. Research suggests that sulfur-containing compounds like sulfur dioxide played an important role in driving metabolic reactions on the primitive Earth.

Image B: Complex Organic Molecules in IRAS 2A

Graphic titled “NGC 1333 IRAS 2A Protostar, MIRI Medium -Resolution Spectroscopy” shows a graph of optical depth on the y-axis versus wavelength of light in microns on the x-axis. The x-axis ranges from 6.8 microns on the left to 8.6 microns on the right, labeled in even increments of 0.2 microns. The y-axis ranges from 0 on the top to about 0.65 on the bottom, with labeled tick marks at 0.2, 0.4, and 0.6. A jagged white line with several prominent valleys extends horizontally. Vertical bands in different colors mark different wavelength regions and are labeled with molecular names and formulas.

NASA’s James Webb Space Telescope’s MIRI (Mid-Infrared Instrument) has identified a variety of complex organic molecules that are present in interstellar ices surrounding two protostars. These molecules, which are key ingredients for making potentially habitable worlds, include ethanol, formic acid, methane, and likely acetic acid, in the solid phase. The finding came from the study of two protostars, IRAS 2A and IRAS 23385, both of which are so young that they are not yet forming planets.

Illustration: NASA, ESA, CSA, L. Hustak (STScI). Science: W. Rocha (Leiden University).

Similar to the early stages of our own solar system?

Of particular interest is that one of the sources investigated, IRAS 2A, is characterized as a low-mass protostar. IRAS 2A may therefore be similar to the early stages of our own solar system. As such, the chemicals identified around this protostar may have been in the first stages of development of our solar system and later delivered to the primitive Earth.

“All of these molecules can become part of comets and asteroids and eventually new planetary systems when the icy material is transported inward to the planet-forming disk as the protostellar system evolves,” said Ewine van Dishoeck of Leiden University, one of the coordinators of the science program. “We look forward to following this astrochemical trail step-by-step with more Webb data in the coming years.”

These observations were made for the JOYS+ (James Webb Observations of Young ProtoStars) program. The team dedicated these results to team member Harold Linnartz, who unexpectedly passed away in December 2023, shortly after the acceptance of this paper.

This research has been accepted for publication in the journal Astronomy & Astrophysics.

The James Webb Space Telescope is the world's premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

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This research has been accepted for publication in the journal Astronomy & Astrophysics.