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Penn State Scranton professor receives NSF grant to study white dwarf stars

Agnes Kim, associate professor of physics at Penn State Scranton, has received a National Science Foundation grant aimed at enhancing the understanding of white dwarf stars. Credit: Morgan Sewack / Penn State. Creative Commons

DUNMORE, Pa. — Agnes Kim, associate professor of physics at Penn State Scranton, has received a National Science Foundation (NSF) grant aimed at enhancing the understanding of white dwarf stars.

The $363,623 grant, titled: "Collaborative Research:  The Seismic Technique for Accurate White Dwarf Parameters," is a collaborative project with Assistant Professor of Physics Keaton Bell from CUNY Queens College.

The primary focus of Kim’s research is to improve the accuracy of temperature and gravity measurements for white dwarfs, which are the remnants of stars that have exhausted their nuclear fuel. Kim said that achieving precise measurements has been challenging due to discrepancies in existing data.

“Ever since I started in the field in 2003, obtaining accurate measurements of the temperatures and surface gravities of white dwarfs has been difficult,” she said. “For one specific star, G29-38, we have 17 different determinations for its temperature and surface gravity, and while some overlap, none agree.”

Kim’s recent publication, “Constraints from Parallaxes and Average Period Spacings in the Asteroseismic Study of Eight Hydrogen-atmosphere Pulsating White Dwarfs,” explored the thickness of helium and hydrogen layers in white dwarfs and relates closely to the goals of the NSF-funded project.

The collaboration between Kim and Bell originated at a conference in Hilo, Hawaii, in 2019, shortly before the onset of the COVID-19 pandemic.

“I had just presented on how difficult it was to determine the mass and temperature of white dwarfs from asteroseismology alone, and how all over the place the spectroscopy was," she said. "Keaton and I talked after the presentation and the idea for the project formed. He is an expert on measuring pulsations and on doing statistics, while I have two decades of experience producing and using grids of white dwarf models."

Bell specializes in measuring pulsations and statistical analysis, while Kim brings extensive experience in white dwarf modeling.

Utilizing data from the Gaia space mission

The research will also utilize data from the Gaia space mission, which has provided precise distances for over 260,000 stars, including about 250 pulsating white dwarfs.

“There have been ground based observations and space missions before Gaia to measure distances, but Gaia is unprecedented in its scope and precision. Distances are the holy grail in astronomy and it's a shame not to use that information,” Kim said.

By combining this information with the pulsations of white dwarfs, Kim and Bell aim to create a systematic and statistically solid approach to measuring their properties.

White dwarfs are important objects in astrophysics, as they account for about 97% of stars, including our sun, at the end of their life cycles. Their study can reveal insights into the physical processes that govern stellar evolution.

“The coolest white dwarfs in our galaxy are used to determine the age of the Milky Way,” Kim said. “Understanding these stars helps us learn about the history and evolution of our galaxy.”

Undergraduate research opportunities

The grant’s objectives include creating undergraduate research opportunities. Kim is currently working with two students from University Park on this initiative.

“This will allow students to engage in research, develop skills and form connections with faculty,” Kim said.

Students who participate in the research project will gain practical experience in scientific methods and data analysis. Kim emphasized the importance of such opportunities: “Involvement in undergraduate research offers students a chance to develop both technical and soft skills outside the classroom,” she said.

The academic community has shown interest in Kim’s recent work. She said that her recent paper received positive feedback, and a related YouTube video achieved notable viewership.

“The video was ranked No. 3 among recent releases within its first four days,” Kim said. “I’ve received encouraging reactions from colleagues and friends.”

In addition to the research opportunities, Kim expressed excitement about collaborating with Bell and his doctoral students.

“Having the grant ensures that we can devote time and resources to this project,” she said. “We have been working [on it] on and off since early 2020, and this focused effort will help bring the project to completion.”

Looking ahead, Kim said she and her team are preparing to implement their research methodologies.

“We hope to be able to produce, for a number of pulsating white dwarfs, precise, reliable determinations of their mass and surface temperature. That would be new and very good to have. There are also by products of the research, tools that will be useful for the research community,” she said.

Fostering discovery through research

Kim's work is expected to have a lasting impact on the field, especially as it relates to understanding the end stages of stellar evolution. Through her work, Kim said she aims to contribute to a deeper understanding of white dwarf stars and their significance in the cosmos. As the project progresses, she said she looks forward to sharing her findings with both the academic community and her students at Penn State Scranton.

As Kim prepares to embark on this new phase of research, she said she remains committed to mentoring students and advancing scientific knowledge in the field of astrophysics.

“Research is challenging and can definitely be tedious," she said, "but there is the excitement of discovery that makes it all worth it.”

Last Updated October 31, 2024

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