About Me

Hello! My name is Samantha Wu and I am a Carnegie Theoretical Astrophysics Center Fellow, based at Carnegie Observatories in Pasadena. I completed my Ph.D. in Astrophysics at Caltech in May 2024. For my research, I work on theoretical stellar astrophysics, using numerical calculations to study the interiors of stars.

Before coming to Caltech, I earned bachelor's degrees in Applied Mathematics and Astrophysics at UC Berkeley. At Berkeley, I started out in astronomy research with projects about TDEs and the numerics of GRMHD simulations. Between graduating from Berkeley and starting at Caltech, I worked on multi-dimensional hydrodynamical simulations of stellar mergers with Professor Enrico Ramirez-Ruiz's group at UC Santa Cruz.

Research

Publications: on ADS

Research Interests: My current focus lies in the realm of stellar evolution and internal stellar oscillations with applications to pre-supernova outbursts and tidal evolution of exoplanets. I have also worked on interacting stellar binaries and tidal disruption events.

Pre-Supernova Outbursts
A substantial fraction of observed core-collapse supernovae across all spectroscopic types have exhibited signatures of interaction with circumstellar material (CSM) produced by a pre-supernova outburst of material. In some events, luminous pre-supernova outbursts have also been detected. To address this observational puzzle, I have modeled the excitation and transmission of internal gravity waves excited in the cores of massive stars, which can couple with acoustic waves in the envelopes of these massive stars and deposit their energy. This energy deposition has the potential to unbind mass and produce luminous outbursts in the weeks to years before core-collapse. I showed that certain progenitor mass ranges are more likely to exhibit outbursts than others, and wave energy transport can precipitate expansion of stripped helium stars. Pre-supernova mass loss may also be triggered by binary mass transfer between a massive star and its companion. I demonstrated for low-mass helium star progenitors that mass loss during late-stage nuclear burning is consistent with inferred CSM properties of a subset of type Ibn supernovae and ultra-stripped supernovae.

Tidal dissipation in star-planet systems
Working with Dr. Janosz Dewberry , I am studying the dynamical tidal response of stars, which consists of normal modes of stellar oscillation that are excited by the tidal potential of a planetary companion. My current research involves modeling normal modes of oscillation in realistic stellar profiles of fully convective or partially convective stars in order to calculate the frequency-dependent tidal dissipation of the star, coupled with the stellar evolution from the pre-main sequence throughout the main sequence. With this approach, I have resolved orbital migration due to resonance locking, a mechanism by which the tidal potential of the planet resonantly excites a stellar oscillation mode over a prolonged period of time, leading to enhanced tidal dissipation and rapid orbital migration.

Community

Teaching and Mentoring: I developed my passion for teaching while working at the UC Berkeley Student Learning Center, and I remain dedicated to mentoring and STEM pedagogy through the Certificate of Practice in University Teaching at Caltech. I have also mentored for the LAMAT Institute , a REU at UCSC. See my mentee's work here!. At Caltech, I was a mentor for the Caltech Connection Program , which connects students at Pasadena Community College and other minority-serving institutions with Caltech graduate students and postdocs for research experiences.

Outreach: I have enjoyed the opportunity to present a Stargazing Lecture for Caltech Astronomy Outreach , as well as participate in the panels for many other Stargazing Lectures during my time at Caltech. I was a speaker and panelist at the Sequoia National Park Dark Sky Festival in September 2022.

Equity & Inclusion: I served on the organizing committee for Caltech's Gender Minorities and Women in PMA, GWIPMA.

Contact

Email: swu@carnegiescience.edu