Jessica Werk – UW News

The carbon in our bodies probably left the galaxy and came back on cosmic ‘conveyor belt’

James Urton — Fri, 03 Jan 2025 17:39:56 +0000

Life on Earth could not exist without carbon. But carbon itself could not exist without stars. Nearly all elements except hydrogen and helium — including carbon, oxygen and iron — only exist because they were forged in stellar furnaces and later flung into the cosmos when their stars died. In an ultimate act of galactic recycling, planets like ours are formed by incorporating these star-built atoms into their makeup, be it the iron in Earth’s core, the oxygen in its atmosphere or the carbon in the bodies of Earthlings.

A team of scientists based in the U.S. and Canada recently confirmed that carbon and other star-formed atoms don’t just drift idly through space until they are dragooned for new uses. For galaxies like ours, which are still actively forming new stars, these atoms take a circuitous journey. They circle their galaxy of origin on giant currents that extend into intergalactic space. These currents — known as the circumgalactic medium — resemble giant conveyor belts that push material out and draw it back into the galactic interior, where gravity and other forces can assemble these raw materials into planets, moons, asteroids, comets and even new stars.

An image of a dense, star-rich portion of our galaxy, the Milky Way, taken by the Hubble Space Telescope. Photo: NASA/ESA/Hubble Heritage Team

“Think of the circumgalactic medium as a giant train station: It is constantly pushing material out and pulling it back in,” said team member , a ��Ӱ�Ӵ�ý doctoral candidate. “The heavy elements that stars make get pushed out of their host galaxy and into the circumgalactic medium through their explosive supernovae deaths, where they can eventually get pulled back in and continue the cycle of star and planet formation.”

Garza is lead author on a describing these findings that was published Dec. 27 in the Astrophysical Journal Letters.

“The implications for galaxy evolution, and for the nature of the reservoir of carbon available to galaxies for forming new stars, are exciting,” said co-author , UW professor and chair of the Department of Astronomy. “The same carbon in our bodies most likely spent a significant amount of time outside of the galaxy!”

In 2011, a team of scientists for the first time confirmed the long-held theory that — and that this large, circulating cloud of material includes hot gases enriched in oxygen. Garza, Werk and their colleagues have discovered that the circumgalactic medium of star-forming galaxies also circulates lower-temperature material like carbon.

“We can now confirm that the circumgalactic medium acts like a giant reservoir for both carbon and oxygen,” said Garza. “And, at least in star-forming galaxies, we suggest that this material then falls back onto the galaxy to continue the recycling process.”

Studying the circumgalactic medium could help scientists understand how this recycling process subsides, which will happen eventually for all galaxies — even ours. One theory is that a slowing or breakdown of the circumgalactic medium’s contribution to the recycling process may explain why a galaxy’s stellar populations decline over long periods of time.

“If you can keep the cycle going — pushing material out and pulling it back in — then theoretically you have enough fuel to keep star formation going,” said Garza.

In this artistic rendering, light from a distant quasar passes through the halo-like circumgalactic medium of a galaxy on its way to Earth, where it is measured by Hubble’s Cosmic Origins Spectrograph to determine the composition of the halo. Photo:

For this study, the researchers used the Cosmic Origins Spectrograph on the Hubble Space Telescope. The spectrograph measured how light from nine distant quasars — ultra-bright sources of light in the cosmos — is affected by the circumgalactic medium of 11 star-forming galaxies. The Hubble readings indicated that some of the light from the quasars was being absorbed by a specific component in the circumgalactic medium: carbon, and lots of it. In some cases, they detected carbon extending out almost 400,000 light years — or four times the diameter of our own galaxy — into intergalactic space.

Future research is needed to quantify the full extent of the other elements that make up the circumgalactic medium and to further compare how their compositions differ between galaxies that are still making large amounts of stars and galaxies that have largely ceased star formation. Those answers could illuminate not just when galaxies like ours transition into stellar deserts, but why.

Co-authors on the paper are , research fellow at the Herzberg Astronomy and Astrophysics Research Centre in British Columbia; , a UW postdoctoral researcher in astronomy; , a research fellow at the University of Colorado Boulder; , assistant professor of physics at North Carolina State University; and , professor of physics and astronomy at the University of Victoria. The research was funded by NASA and the National Science Foundation.

For more information, contact Garza at samgarza@uw.edu and Werk at jwerk@uw.edu.

Five UW scientists awarded Sloan Fellowships for early-career research

Jackson Holtz — Thu, 15 Feb 2018 15:06:09 +0000

Five faculty members at the ��Ӱ�Ӵ�ý have been awarded early-career from the Alfred P. Sloan Foundation. The new Sloan Fellows, Feb. 15, include , assistant professor of computer science and engineering; , assistant professor of clean energy and physics; , assistant professor of electrical engineering and physics; , assistant professor of astronomy; and , assistant professor of aquatic and fishery sciences.

Open to scholars in eight scientific and technical fields — chemistry, computer science, economics, mathematics, molecular biology, neuroscience, ocean sciences and physics — the fellowships honor those early-career researchers whose achievements mark them as the next generation of scientific leaders.

The 126 were selected in close coordination with the research community. Candidates are nominated by their peers, and fellows are selected by independent panels of senior scholars based on each candidate’s research accomplishments, creativity and potential to become a leader in his or her field. Each fellow will receive $65,000 to apply toward research endeavors.

This year’s fellows come from 53 institutions across the United States and Canada, spanning fields from evolutionary biology to data science. The new Sloan Fellows at the UW reflect this diversity, probing complex questions in robotics, quantum physics and the formation of the galaxy.

Maya Cakmak Photo: ��Ӱ�Ӵ�ý

Cakmak, for example, directs the , where she studies human-robot interactions, end-user programming and assistive robotics. She aims to develop robots that can be programmed and controlled by diverse users.

“It’s about packaging robot capabilities at the right level and creating the right interface for different users,” said Cakmak.

Rather than aiming for a one-size-fits-all robot, Cakmak argues for customizing each robot to the unique needs, preferences and environments of users. Today, only expert roboticists can do that sort of customization. Cakmak aims to make robot programming accessible to a much wider audience. She believes this could be the key to mass adoption of robots and democratize “robot programming” jobs of the future.

Jiun-Haw Chu Photo: ��Ӱ�Ӵ�ý

Chu, of the , focuses on the synthesis and characterization of materials with unconventional electronic and magnetic ground states, such as high-temperature superconductors and topological insulators. Simply put, Chu manufactures materials and measures their properties.

“My goal is to find more materials of this kind and study their properties to find why they come out this way, or if there are additional hidden properties that people don’t know about,” said Chu.

The goal is to understand and control these emergent quantum behaviors and apply them to energy and information technology.

Arka Majumdar Photo: ��Ӱ�Ӵ�ý

Majumdar, a researcher with the , is at the forefront of the interdisciplinary research that combines quantum materials and nanophotonics. His research attempts to store light in an optical resonator to study its tiniest components. Majumdar is setting out to build quantum systems using light that can mimic the interactions between electrons in many of today’s technologies. That would pave the way for new materials and optical nano-structures that could revolutionize computing. Developing these technologies, however, can be very difficult.

“Our plan is to engineer new materials and new optical nanostructures to make photons interact with each other, which is a key element for performing computation with light, be it quantum or classical computing,” said Majumdar.

Jessica Werk Photo: ��Ӱ�Ӵ�ý

Werk is a kind of galaxy historian, studying matter on atomic scales to help understand how galaxies — and the universe as a whole — evolve. By aiming giant telescopes at the night’s sky, she uses spectrographs to study atoms billions of light years away. Werk looks at the distinction between subatomic particles that exist both outside and inside galaxies. The outcome, she hopes, will help elucidate a better understanding of our own cosmic origins.

“When I look at the sky I see lots of different atomic transitions that I’m trying to piece together into a coherent picture,” said Werk.

Chelsea Wood Photo: ��Ӱ�Ӵ�ý

�´Ǵǻ�’s research explores the ecology of parasites and pathogens in a changing world. She is interested in how human impacts on ecosystems affect the transmission of parasites. �´Ǵǻ�’s work has shown that disruption can alter what kinds of parasites are common and rare — increasing the abundance of some kinds of parasites and decreasing the abundance of others. The Sloan Fellowship will allow Wood and her team to look back in time at how parasite transmission changed as industrialization intensified human impacts on the oceans. She’ll accomplish this by examining parasites preserved in museum specimens — mainly fish floating perennially in ethanol — including many that are more than a century old.

“These fish are basically parasite time capsules,” said Wood.

By developing time profiles of parasite abundance, Wood will provide the world’s first glimpse of what parasite communities might have been like in a more “pristine” ocean.

###

For more information, contact Jackson Holtz at the UW News Office at 206-543-2580 or jjholtz@uw.edu.