ASU scientists lead study of galaxy's 'water worlds'

April 20, 2020

Astrophysical observations have shown that Neptune-like water-rich exoplanetsPlanets around other stars. are common in our galaxy. These “water worlds” are believed to be covered with a thick layer of water, hundreds to thousands of miles deep, above a rocky mantle. 

While water-rich exoplanets are common, their composition is very different from Earth, so there are many unknowns in terms of these planets’ structure, composition and geochemical cycles. Artist’s impression of planet K2-18b, a super-Earth exoplanet known to host both water and temperatures that could support life. Credit: ESA/Hubble, M. Kornmesser Download Full Image

In seeking to learn more about these planets, an international team of researchers, led by Arizona State University, has provided one of the first mineralogy lab studies for water-rich exoplanets. The results of their study have been recently published in the journal Proceedings of the National Academy of Sciences.

“Studying the chemical reactions and processes is an essential step toward developing an understanding of these common planet types,” said co-author Dan Shim, of ASU's School of Earth and Space Exploration.

The general scientific conjecture is that water and rock form separate layers in the interiors of water worlds. Because water is lighter, underneath the water layer in water-rich planets, there should be a rocky layer. However, the extreme pressure and temperature at the boundary between water and rocky layers could fundamentally change the behaviors of these materials.

To simulate this high pressure and temperature in the lab, lead author and research scientist Carole Nisr conducted experiments at Shim’s Lab for Earth and Planetary Materials at ASU using high pressure diamond-anvil cells.

For their experiment, the team immersed silica in water, compressed the sample between diamonds to a very high pressure, then heated the sample with laser beams to over a few thousand degrees Fahrenheit.

The team also conducted laser heating at the Argonne National Laboratory in Illinois. To monitor the reaction between silica and water, X-ray measurements were taken while the laser heated the sample at high pressures. 

What they found was an unexpected new solid phase with silicon, hydrogen and oxygen all together.

“Originally, it was thought that water and rock layers in water-rich planets were well-separated,” Nisr said. “But we discovered through our experiments a previously unknown reaction between water and silica and stability of a solid phase roughly in an intermediate composition. The distinction between water and rock appeared to be surprisingly 'fuzzy' at high pressure and high temperature.”

The researchers hope that these findings will advance our knowledge on the structure and composition of water-rich planets and their geochemical cycles.

“Our study has important implications and raises new questions for the chemical composition and structure of the interiors of water-rich exoplanets,” Nisr said. “The geochemical cycle for water-rich planets could be very different from that of the rocky planets, such as Earth.”

In addition to Nisr and Shim, co-authors from ASU include alumni Huawei Chen; Kurt Leinenweber of ASU’s Eyring Materials Center; and Andrew Chizmeshya of ASU’s School of Molecular Sciences. Additional researchers on the team represent the University of Chicago, University of Cologne (Germany), Argonne National Laboratory (Illinois) and George Washington University (Washington, D.C.).

Karin Valentine

Media Relations & Marketing manager, School of Earth and Space Exploration


ASU Kerr shines spotlight on local storytellers for ‘Gather’

New digital event brings together notable artists to share stories centered around the city of Phoenix

April 20, 2020

ASU Kerr Cultural Center will present “Gather,” a new digital storytelling event, at 6:30 p.m. on Thursday, April 23, via the venue’s Facebook Live page.

Co-presented by ASU Cultural Affairs venues ASU Kerr and ASU Gammage, the event is part of several livestreamed events that ASU Kerr will broadcast via Facebook Live in the month of April. Pianist and Phoenix jazz favorite Charles Lewis. Download Full Image

The livestream will feature three diverse and experienced storytellers: founder of Bicycle Nomad Erick Cedeño; Mathew Sandoval, faculty fellow at ASU’s Barrett, The Honors College in downtown Phoenix; and producer of the Storyline SLAM Dan Hoen Hull. In this first edition of “Gather,” stories centering around Phoenix will be shared, the craft of storytelling will be discussed and its future in the contemporary desert landscape will be celebrated. Pianist and local jazz favorite Charles Lewis will also perform during the streaming show.

“We hope to create inspiring digital gatherings that keep us connected to the stories, art and music of Phoenix-area residents during a time of increased isolation,” ASU Kerr General Manager Tracey Mason said.

Christine Anglin, ASU Kerr’s contracts and administration coordinator, and Fernanda Snellings, ASU Gammage’s artist liaison and engagement manager, are behind the “Gather” series. Impressed by the high caliber of storytellers in the Phoenix metropolitan area and driven by their own work as storytellers and poets, respectively, the pair have set out to present artists and compelling work that encourages listeners to share their own stories, Anglin said.

“Stories connect people and show us that we are not so different ... our stories speak to who we are,” Anglin said. “Phoenix has an active storytelling community filled with extremely talented storytellers ... and those who are willing to listen.”

Viewers can expect to be hoisted from their living rooms, bedrooms and kitchens and brought into a new world curated by the storyteller, Anglin added.

“We are proud to be able to share new livestreaming programming that supports Phoenix-area artists,” Mason said. “We want to strengthen the bonds between local creators, residents, viewers beyond Arizona and the beauty of the arts in any way we can.”

More information on “Gather” and other upcoming virtual events.

Marketing Communications Assistant, ASU Gammage