Oort constants describe the motions of stars near the sun, but they are also useful for determining the model of Milky Way kinematics, or how stars, gas, and objects move in our galaxy.
“It is a great example of how you use fundamental physics and mathematical concepts to study something in the larger picture,” said Shufan Xia ’21.
The physics major, scientific computation concentration, and Bryn Mawr history minor used data from the space telescope Gaia to measure accurate Oort constants in her thesis. She compared these observational results to a theoretical model of the Milky Way she simulated.
Her research began with learning about Oort constants and looking to existing research to see how she could calculate them herself. During this process, she found that Oort constants are only accurate for a small region near the Sun under strict simplified conditions, which do not match the complex reality of the Milky Way galaxy.
“With the reality that the Milky Way deviates from the simple assumptions in the Oort constants, we had to take a further look at how to measure them from huge observation data,” she said. “Besides setting up the procedures to find the Oort constants, we focused on finding where in the Milky Way around the solar vicinity and what groups of stars are those under the constraint of the Oort constants.”
The procedure that Xia and her advisors created provides guidance for other astronomers to use Oort constants in the future. What began as a roadblock, ended up leading to her thesis’ greatest contribution.
This fall, Xia is starting her master’s in interdisciplinary data science at Duke University. She wants to take the programming and data skills that she learned during her thesis process into her quantitative social science research in graduate school.
Who were your thesis advisors?
My thesis advisors are Dr. Zhao-Yu Li from Shanghai Jiaotong University and Professor Karen Masters. Professor Masters helped me contact one of her acquittances in my home city because I was hoping to stay in Shanghai during the summer last year. Dr. Li happily took me. […] We talked and discussed intermediate results weekly, during which Dr. Li and Professor Masters would help me answer any questions I had from the week and discuss what further investigations I could do. I did not have many experiences with astronomy, so have often relied on Dr. Li and Professor Masters to draw their astronomy knowledge to interpret and explain the anomalies I saw in my results.
What did you learn from working on your thesis?
I think I have grown the most at the soft skills of conducting research and collaborating. Since Dr. Li worked across a different time zone and Professor Masters has different expertise, I felt my research was more of an independent project. I had a lot of control on the thesis, but at the same time, it necessitated me to take the lead in what to do in my research. … I learned I really need to take initiative in progressing my work and communicating with my advisors. … I started to organize all of my weekly progress in written documents. It gave me motivation to process and organize the project, to reflect the questions I had, and emphasize the problems and the next steps of the project. Every week, I had a small formal report, which took more time to write, but it made showing my work so much easier and ultimately became a great resource for me to look back at when I put my thesis together in the drafts.
“What They Learned” is a blog series exploring the thesis work of recent graduates.