From The University of Colorado-Boulder: “A star is born – Study reveals complex chemistry inside ‘stellar nurseries’”
From The University of Colorado-Boulder
2.6.23
Daniel Strain
daniel.strain@colorado.edu
Gas and dust swirl in the Taurus Molecular Cloud (TMC-1) as seen by the Herschel Space Observatory. (Credit: ESA/Herschel; R. Hurt/JPL-Caltech/NASA; CC BY-SA 3.0 IGO)
An international team of researchers has uncovered what might be a critical step in the chemical evolution of molecules in cosmic “stellar nurseries.” In these vast clouds of cold gas and dust in space, trillions of molecules swirl together over millions of years. The collapse of these interstellar clouds eventually gives rise to young stars and planets.
Like human bodies, stellar nurseries contain a lot of organic molecules, which are made up mostly of carbon and hydrogen atoms. The group’s results, published Feb. 6 in the journal Nature Astronomy [below], reveal how certain large organic molecules may form inside these clouds. It’s one tiny step in the eons-long chemical journey that carbon atoms undergo—forming in the hearts of dying stars, then becoming part of planets, living organisms on Earth and perhaps beyond.
“In these cold molecular clouds, you’re creating the first building blocks that will, in the end, form stars and planets,” said Jordy Bouwman, research associate at the Laboratory for Atmospheric and Space Physics (LASP) and assistant professor in the Department of Chemistry at CU Boulder.
Graphic showing how hexagonally-shaped ortho-benzyne molecules can combine with methyl radicals to form a series of larger organic molecules, each containing a ring of five carbon atoms. (Credit: Henry Cardwell)
For the new study, Bouwman and his colleagues took a deep dive into one stellar nursery in particular: the Taurus Molecular Cloud (TMC-1). This region sits in the constellation Taurus and is roughly 440 light years (more than 2 quadrillion miles) from Earth. The chemically complex environment is an example of what astronomers call an “accreting starless core.” Its cloud has begun to collapse, but scientists haven’t yet detected embryonic stars emerging inside it.
The team’s findings hinge on a deceptively simple molecule called ortho-benzyne. Drawing on experiments on Earth and computer simulations, the researchers showed that this molecule can readily combine with others in space to form a wide range of larger organic molecules.
Small building blocks, in other words, become big building blocks.
And, Bouwman said, those reactions could be a sign that stellar nurseries are a lot more interesting than scientists give them credit for.
“We’re only at the start of truly understanding how we go from these small building blocks to larger molecules,” he said. “I think we’ll find that this chemistry is so much more complex than we thought, even at the earliest stages of star formation.”
Fateful observation
Bouwman is a cosmochemist, studying a field that blends chemistry and astronomy to understand the churning chemical reactions that happen deep in space.
On the surface, he said, cold molecular clouds might not seem like a hotbed of chemical activity. As their name suggests, these galactic primordial soups tend to be frigid, often hovering around -263 degrees Celsius (about -440 degrees Fahrenheit), just 10 degrees above absolute zero. Most reactions need at least a little bit of heat to get a kick-start.
But cold or not, complex chemistry seems to be happening in stellar nurseries. TMC-1, in particular, contains surprising concentrations of relatively large organic molecules with names like fulvenallene and 1- and 2-ethynylcyclopentadiene. Chemists call them “five-membered ring compounds” because they each contain a ring of carbon atoms shaped like a pentagon.
“Researchers kept detecting these molecules in TMC-1, but their origin was unclear,” Bouwman said.
Now, he and his colleagues think they have an answer.
In 2021, researchers using the Yebes 40-metre Radio telescope in Spain found an unexpected molecule hiding in the clouds of gas of TMC-1: ortho-benzyne.
Yebes Observatory RT40m (ES). European VLBI Network (EU) (EVN)
Bouwman explained that this small molecule, made up of a ring of six carbon atoms with four hydrogens, is one of the extroverts of the chemistry world. It easily interacts with a number of other molecules and doesn’t require a lot of heat to do so.
“There’s no barrier to reaction,” Bouwman said. “That means it has the potential to drive complex chemistry in cold environments.”
Identifying the culprit
To find out what kind of complex chemistry was happening in TMC-1, Bouwman and his colleagues—who hail from the United States, Germany, the Netherlands and Switzerland—turned to a technique called “photoelectron photoion coincidence spectroscopy.” The team used light generated by a giant facility called a synchotron light source to identify the products of chemical reactions.
They saw that ortho-benzyne and methyl radicals, another common constituent of molecular clouds, readily combine to form larger and more complex organic compounds.
“We knew we were onto something good,” Bouwman said.
The team then drew on computer models to explore the role of ortho-benzyne in a stellar nursery spread out over several light-years deep in space. The results were promising: The models generated clouds of gas containing roughly the same mix of organic molecules that astronomers had observed in TMC-1 using telescopes.
Ortho-benzyne, in other words, seems to be a prime candidate for driving the gas-phase organic chemistry that occurs within these stellar nurseries, Bouwman said.
He added that scientists still have a lot of work to do to fully understand all of the reactions happening in TMC-1. He wants to examine, for example, how organic molecules in space also pick up nitrogen atoms—key components of the DNA and amino acids of living organisms on Earth.
“Our findings may just change the view on what ingredients we have in the first place to form new stars and new planets,” Bouwman said.
Co-authors on the new paper include researchers at Leiden University in the Netherlands, Benedictine College in the U.S., the University of Würzburg in Germany and Paul Scherrer Institute in Switzerland.
See the full article here .
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University of Colorado-Boulder has blossomed in size and quality since we opened our doors in 1877 – attracting superb faculty, staff, and students and building strong programs in the sciences, engineering, business, law, arts, humanities, education, music, and many other disciplines.
Today, with our sights set on becoming the standard for the great comprehensive public research universities of the new century, we strive to serve the people of Colorado and to engage with the world through excellence in our teaching, research, creative work, and service.
In 2015, the university comprised nine colleges and schools and offered over 150 academic programs and enrolled almost 17,000 students. Five Nobel Laureates, nine MacArthur Fellows, and 20 astronauts have been affiliated with CU Boulder as students; researchers; or faculty members in its history. In 2010, the university received nearly $454 million in sponsored research to fund programs like the Laboratory for Atmospheric and Space Physics and JILA. CU Boulder has been called a Public Ivy, a group of publicly funded universities considered as providing a quality of education comparable to those of the Ivy League.
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On March 14, 1876, the Colorado territorial legislature passed an amendment to the state constitution that provided money for the establishment of the University of Colorado in Boulder, the Colorado School of Mines in Golden, and the Colorado State University – College of Agricultural Sciences in Fort Collins.
Two cities competed for the site of the University of Colorado: Boulder and Cañon City. The consolation prize for the losing city was to be home of the new Colorado State Prison. Cañon City was at a disadvantage as it was already the home of the Colorado Territorial Prison. (There are now six prisons in the Cañon City area.)
The cornerstone of the building that became Old Main was laid on September 20, 1875. The doors of the university opened on September 5, 1877. At the time, there were few high schools in the state that could adequately prepare students for university work, so in addition to the University, a preparatory school was formed on campus. In the fall of 1877, the student body consisted of 15 students in the college proper and 50 students in the preparatory school. There were 38 men and 27 women, and their ages ranged from 12–23 years.
During World War II, Colorado was one of 131 colleges and universities nationally that took part in the V-12 Navy College Training Program which offered students a path to a navy commission.
University of Colorado-Boulder hired its first female professor, Mary Rippon, in 1878. It hired its first African-American professor, Charles H. Nilon, in 1956, and its first African-American librarian, Mildred Nilon, in 1962. Its first African American female graduate, Lucile Berkeley Buchanan, received her degree in 1918.
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The Institute for Behavioral Genetics (IBG) is a research institute within the Graduate School dedicated to conducting and facilitating research on the genetic and environmental bases of individual differences in behavior. After its founding in 1967 IBG led the resurging interest in genetic influences on behavior. IBG was the first post-World War II research institute dedicated to research in behavioral genetics. IBG remains one of the top research facilities for research in behavioral genetics, including human behavioral genetics, psychiatric genetics, quantitative genetics, statistical genetics, and animal behavioral genetics.
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ATLAS Institute is a center for interdisciplinary research and academic study, where engineering, computer science and robotics are blended with design-oriented topics. Part of CU Boulder’s College of Engineering and Applied Science, the institute offers academic programs at the undergraduate, master’s and doctoral levels, and administers research labs, hacker and makerspaces, and a black box experimental performance studio. At the beginning of the 2018–2019 academic year, approximately 1,200 students were enrolled in ATLAS academic programs and the institute sponsored six research labs.[64]
In addition to IBG, ICS and ATLAS, the university’s other institutes include Biofrontiers Institute, Cooperative Institute for Research in Environmental Sciences, Institute of Arctic & Alpine Research (INSTAAR), Institute of Behavioral Science (IBS), JILA, Laboratory for Atmospheric & Space Physics (LASP), Renewable & Sustainable Energy Institute (RASEI), and the University of Colorado Museum of Natural History.
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