VOA科学技术2023--Astronomers Observe Most Distant Organic Molecules in Universe（在线收听）

Astronomers Observe Most Distant Organic Molecules in Universe

Scientists say they have observed the most distant organic molecules known to exist in the universe.

Astronomers made the discovery using the James Webb Space Telescope, operated by the American space agency NASA.

The kind of organic molecules observed are called polycyclic aromatic hydrocarbons, or PAHs. These molecules are considered the basic building blocks for early forms of life. They have a complex structure and are found in many environments on our own planet. For example, PAHs can be found on Earth in smoke, burned materials and air pollution.

The molecules were discovered in a galaxy more than 12 billion light years from Earth. The scientists say this is the most distant observation of PAHs ever.

Past observations of PAHs have been difficult in distant galaxies because of limitations in infrared telescope technology. But the James Webb's sensitive instruments made the discovery possible, the researchers said.

The team said that because of the extreme distance involved, the light used to make the observation likely began traveling when the universe was less than 1.5 billion years old. This is about 10 percent of the universe's current age.

The astronomers recently reported their findings in a study in the publication Nature.

The targeted galaxy is known as SPT0418-47. Scientists had already identified it as a galaxy similar to our own Milky Way in several ways. But the amount of dust surrounding it made past observations difficult.

The researchers said telescope data permitted them to differentiate between infrared signals produced by larger dust particles and those produced by PAHs.

Justin Spilker is an astronomer at Texas A&M University. He helped lead the research. He said in a statement that PAHs are "actually pretty common in space." But the latest research helped astronomers learn new things about them.

"Astronomers used to think they were a good sign that new stars were forming," Spilker said. "Anywhere you saw these molecules, baby stars were also right there..." Spilker noted that the power of the James Webb telescope permitted the team to find many areas with smoke but no star formation.

The researchers said an observation method called gravitational lensing also helped them. This method involves observing how the gravity of large collections of galaxies can distort the light of more distant galaxies that sit behind the galaxy group, NASA explains. To distort means to change the natural or normal quality of something.

Joaquin Vieira is a professor of astronomy and physics at the University of Illinois Urbana-Champaign. He was a lead researcher on the project. Vieira said that the combined abilities of James Webb and gravitational lensing made it possible for the researchers to observe through the dust to identify the PAHs.

Observations of the targeted galaxy suggested it contained gas filled with heavy elements. This means that generations of stars had already lived and died there, the team said.

Vieira said the findings were completely unexpected and could be a "game-changer" for future observations of distant galaxies.

"This work is just the first step, and we're just now learning how to use (the telescope) and learn its capabilities." He added, "We are very excited to see how this plays out."

The astronomers are looking forward to using the same equipment and methods to find out more about the early formation of the universe.

Texas A&M's Spilker said he is "excited to see all the new things" the James Webb can do for astronomers in the future.

"Detecting smoke in a galaxy early in the history of the universe? Webb makes this look easy," Spilker said. "Now that we've shown this is possible for the first time, we're looking forward to trying to understand whether it's really true that where there's smoke, there's fire," he added.

Words in This Story

organic – adj. used in chemistry to describe chemicals that contain carbon

galaxy – n. a very large group of stars held together in the universe

distort – v. to change the shape, sound or appearance of something

capability – n. the ability or power to do something

where there's smoke, there's fire - idiom a phrase meaning there are signs that something is true so it must be at least partly true