About me

I am a PhD candidate at the California Institute of Technology (Pasadena, CA), working with Prof. Kareem El-Badry. I am interested in understanding the life and death of stars through observations of binary stars.

I am originally from Japan but have been living in the US for over 10 years. Before graduate school, I worked with Prof. Kevin Burdge at MIT (Cambridge, MA), where I earned my B.S. in Physics and Music. Outside of astrophysics, I like to play percussion, read books, and bake.

Full CV
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Research Interests

  • Binary stars
  • Intermediate-mass stripped stars
  • Observations and modeling
  • Hot subdwarf (sdB) stars

A large fraction of stars live in binary or higher order systems and will interact with a companion at least once within their lifetimes. Understanding these interactions is therefore essential for building a complete picture of stellar evolution. Sripped stars -- which have lost their hydrogen envelopes through binary interactionsn and are therefore products of recent binary interaction-- provide a window into how binary interactions shape stellar evolution processes. They are also progenitors to many astrophysically interesting systems, such as stripped supernovae, compact-object binaries, and gravitational wave sources, making them relevant to a broad range of astrophysical questions.

My research focuses on discovering and characterizing low- and intermediate-mass stripped stars and using those population to contrain binary evolution processes. I am primarily an observational astrophysicist, working across ultraviolet and optical using both photometry and spectroscopy. My research utilizes both archival data and targeted followed-up observations using state-of-the-art facilities such as Keck and Magellan. I also use population synthesis and forward modeling techniques to understand observational and selection biases and connect observed samples to the underlying population.

Publications

You can also access my complete publication record on NASA ADS or arXiv.

First-author publications

Co-authored publications

A Galactic intermediate-mass stripped star with a Wolf-Rayet-like wind

Johanna Müller-Horn, Kareem El-Badry, Andreas A. C. Sander, Hans-Walter Rix, Lisa Blomberg, J. J. Hermes, Pranav Nagarajan, Sahar Shahaf, Harim Jin, Dominick M. Rowan, Debasish Dutta, José G. Fernández-Trincado, Ylva Götberg, Ilya Ilyin, Tom Maccarone, José Eduardo Méndez Delgado, Guy S. Stringfellow, Andrew Tkachenko, Jaime I. Villaseñor, and Eleonora Zari (2026)

A systematic survey for hypervelocity runaways from thermonuclear supernovae

Kareem El-Badry, Klaus Werner, Ken J. Shen, Jay Strader, Antonio C. Rodriguez, Jiwon Jesse Han, Vedant Chandra, Laura Chomiuk, Zachary P. Vanderbosch, Lisa Blomberg, Natsuko Yamaguchi, Pranav Nagarajan, Ilaria Caiazzo, Jan van Roestel, Hila Glanz, Tin Long Sunny Wong, Aakash Bhat, Mark A. Hollands, and Boris T. Gänsicke (2026)

Teaching / Mentoring

In addition to research, I am also passionate about STEM education. Over the years, I have taught in K–12 and higher education settings, both locally and internationally. Alongside my thesis research, I am working toward completing Caltech's Certificate of Practice (CoP) in University Teaching.

I believe the role of an educator extends beyond teaching students the course material. As an instructor and mentor, I aim to help students/mentees develop critical thinking skills that can be applied in a variety of settings. Ultimately, I want my students to leave not only with a stronger understanding of the subject, but also greater confidence in their ability to tackle unfamiliar problems and learn independently.

Selected teaching experience

Graduate Teaching Assistant

California Institute of Technology

  • Ph 1b: Classical Mechanics and Electromagnetism (Winter 2025)
  • Ph 1a: Classical Mechanics and Electromagnetism (Fall 2024)
  • Ph 1c: Classical Mechanics and Electromagnetism (Spring 2024)
  • Ph 77: Advanced Physics Laboratory (Winter 2024)

MIT Global Teaching Lab

Niccolò Copernico State Scientific High School · Prato, Italy

  • Developed curriculum and taught special relativity to approximately 150 high school students
Global Teaching Labs website

Undergraduate Teaching Assistant

Massachusetts Institute of Technology

  • 8.13: Experimental Physics I (Fall 2022, Spring 2023)

Contact Me

Feel free to reach out to me via email :)

lblomber@caltech.edu