Profile 04 Miho Ishigaki

Name: MIHO ISHIGAKI (Astronomer)
Hometown: Higashimatsushima, Miyagi Prefecture. The coastal area of my hometown was hit by the tsunami after the 2011 Japan Earthquake, but my family was safe because we live further inland.
Position: Kavli IPMU Project Researcher
Recommended reading: Galactic Dynamics (second edition), by J. Binney and S. Tremaine
Favorite place in Japan: I would have to promote my hometown, Higashimatsushima in the Tohoku region. The sushi and seafood is excellent, and it’s very fresh.

What can you tell us about your current research at Kavli IPMU?
I’m interested in old and long-lived stars in our Milky Way Galaxy, particularly their elemental abundances. By studying the chemical elements of stars, you can get a glimpse into chemical elements produced by supernova explosions of previous generations of stars.

Old stars also hint at nature of the First Stars. These are the first stars in the Universe - before them, no stars existed and the Universe was dark. I'm interested in learning the properties of these stars, and what kind of elements produced and ejected by their supernovae. What's amazing is that you can find all these things out by studying the elemental abundances of old stars, which can be used as fossil records of the early universe.

By studying orbital motions of a large number of old stars around the Milky Way, you can also start to predict where these stars came from. Combining elemental abundances and stellar motions is a powerful tool to reconstruct how our Galaxy was created.

What influenced your decision to become an astronomer?
My hometown is in the Tohoku region with rice paddy fields everywhere, but it is a great place for star gazing. When I was little, I loved spotting constellations and using small telescopes to look at the stars. When I was at high school, I used to look at books on stars and began to think very seriously about pursuing this as a career.

Unlike other careers, astronomy sparked my interest because you spent your days working on something you couldn’t reach out and touch with your hands. It was a field where people found creative ways to use the data from observations to calculate how far objects where, or what properties they had.

Can you share your academic background?
My undergraduate, Masters and PhD were all in different fields. I didn't quite get the score needed to enroll into the astronomy program at university, but I knew that physics was fundamental to astronomy, so I embarked on a degree in physics at the International Christian University in Tokyo. Then I spent the next two years at the Tokyo Institute of Technology as part of an infrared astronomy project. After that I went to Tohoku University where I started my PhD in an area of astronomy which is where I still work in today.

While working at the NAOJ (National Astronomical Observatory of Japan) following my PhD, I spent my time analyzing observational data from telescopes to deduce the chemical makeup of stars. But to understand the meaning of the chemical makeup, I thought that working with theoretical researchers would improve my understanding.

What is it like working at the Kavli IPMU?
I’ve always been surrounded by experimental researchers such as myself, so to come into a place where there are just as many theoretical researchers is something very new for me.

I listen to theoretical researchers talk about their work, and sometimes I'm surprised because when they find something interesting, sometimes it will be something I had never looked twice at. It’s a great way to build on my work.

Our personalities can be different as well. Astronomy can be very generalized sometimes. Once we find a positive outcome, we are pretty happy overall. But sometimes that won’t be enough for physicists. They really like checking the probabilities and getting into the details. But this brushes off on my own research in a good way.

What is the next step in your research project?
I’m looking at chemical elements now, and how these elements produced by the first generation of stars. I want to study more stars in the Galaxy, and see how their chemical elements are distributed across space. From that it might be possible to find a constraint to how our Galaxy was created.

Right now, the PFS (Prime Focus Spectrograph) is being built for the Subaru Telescope. Once it is operational in a few years, it’ll make it possible to study the chemical elements of stars on the outer edge of our Galaxy for the first time. Using that data I’m hoping to find a much stronger constraint in regards to how the Galaxy was created.

Where can we find your work?
You can read my papers online (1, 2, 3), and my team's work has been promoted as news on the Kavli IPMU website.