Konstantin Batygin | CALTECH

Ian brunton

Caltech graduate student (planetary science) 2023-

Ian is fascinated by the ways astrophysical processes shape the Solar System, from the disruptive influence of nearby supernovae on Earth’s biosphere to the intricate dynamics of planetary satellites. His current research focuses on developing a theory for the origins of Jupiter’s inner moons, showing how Amalthea and Thebe could have migrated to their present locations through resonant interactions and aerodynamic drag within Jupiter’s primordial disk. In two 2025 studies (ApJ 991, 15; ApJL 990, L11), he showed that Amalthea’s present orbit is naturally explained by inward resonant transport with Io, while Thebe’s orbital history constrains its density to be at least 1 g/cm³, offering new insight into the coupled formation and evolution of Jupiter’s interior satellite system. He has also studied how sharp migration gradients suppress resonant overstability (ApJ 1003, 87).

Teng Ee (Tony) YAP

Caltech graduate student (planetary science) 2022-

Tony obtained his B.A. in Astrogeophysics from Colgate University before joining Caltech in 2022. Passionate about unraveling the early history of the Solar System, his research sits at the intersection of isotope cosmochemistry and planetary astrophysics. He has published on nucleosynthetic isotope anomalies (earning the 2023 Icarus Best Student-Led Paper Award) and on the coupled evolution of dust and gas in protoplanetary disks (arXiv:2408.00159, arXiv:2412.07211), where he developed a self-consistent framework that accounts for turbulent viscosity and magnetically driven winds. Turning to the Jovian satellites, he showed that Callisto’s nonresonant orbit can arise from substructure in Jupiter’s circumplanetary disk (ApJ 995, 218), and that ice lines in circumplanetary decretion disks can produce water-rich satellites (PSJ 2026).

Matthew Belyakov

Caltech postdoctoral scholar (planetary science) 2026 -

Matthew is interested in all things Solar System, including detection, spectroscopy, as well as population studies of outer Solar System objects, and how these can inform theories on the evolution of planetary systems. In his Ph.D. work at Caltech (completed in 2026), he showed that overlapping chains of resonances with Neptune govern the boundary of stability in the scattered disk (Icarus 443, 116773), and, using JWST spectroscopy, that Nereid is a primordial regular satellite of Neptune (Science Advances 12, eaeb1429).

Luke handley

Caltech graduate student (astronomy) 2024-

Luke, an NSF Graduate Research Fellow, is interested in unraveling the dynamics of exoplanetary systems through a combination of observations and theory. In particular, he is using the Keck Planet Finder (KPF) spectrograph at Keck Observatory to measure the spin-orbit alignment of Neptune-like planets across the nearby galaxy, and leads the KPF-SLOPE survey, which finds that compact multi-planet systems are preferentially aligned (arXiv:2603.23713). On the theory side, he showed that photoevaporative disk dispersal alone can drive Neptunes onto polar orbits (ApJ 998, 324). The architectures of these systems tell us something fundamental about the mutual dynamics between young stars, protoplanetary disks, and freshly birthed planets, challenging existing assumptions about planet formation at large.

Valeria Kachmar

Caltech graduate student (planetary science) 2022-

Valeria is broadly interested in the physics of planetary formation and evolution and the (re)cycle of planet-building materials – how do we go from dust to planets of diverse compositions and structures? Which environments are favorable for planetary formation? Currently, she is working on the century-old problem of white dwarf pollution.

Koki Yoshioka

Caltech graduate student (planetary science) 2025 -

Koki works on planet formation at large orbital separations, carrying out large-scale numerical simulations of coagulation and connecting them to the debris disks we observe today.

Pablo Drake

Caltech graduate student (planetary science) 2025 -

Pablo is pushing forward the analytic theory of Kuiper belt dynamics. His work focuses on the formation of the Kuiper belt and on Neptune’s migration within the Nice model, approached from a heavily analytic perspective.

Yinuo han

Caltech Barr Fellow (planetary science) 2024 -

Yinuo’s current work aims to understand the formation and dynamical evolution of planetary systems through the study of debris disks. He explores how planets and small bodies could interact to shape disk structures based on high-resolution imaging from infrared to millimeter wavelengths. He led the radial-structure analysis of the ALMA ARKS survey (A&A 705, A196), measured the multi-wavelength vertical structure of the β Pictoris disk (A&A 711, A42), used JWST to reveal a broad collisional cascade around γ Oph, and developed non-parametric methods to model disk images. Most recently, he showed how planetesimal rings born in protoplanetary disks spread through their mutual gravity, linking protoplanetary and debris disk substructures (arXiv:2608.19329). 

Ruizhe (Roger) Wang

Caltech graduate student (planetary science) 2024 - 2025

Ruizhe carried out calculations of the formation of debris disks around white dwarfs from infalling, highly eccentric asteroids, a key step in explaining how planetary material pollutes white dwarf atmospheres.

Jon Zink

Caltech Hubble Fellow (astronomy/planetary science) 2021 - 2024

Jon used the population of planets around other stars to understand the physical processes that dictate planet formation. To accomplish this goal, he used the K2 mission data to extract a homogeneous catalog of transiting planets. This wide survey of the ecliptic plane enables examination of the stellar host’s role in these formation mechanisms. He also worked on understanding the origins and fate of the solar system, using numerical simulations to constrain the solar birth cluster and the mechanisms responsible for the system’s demise.

Gabriele pichierri

Caltech Barr Fellow (planetary science) 2023 - 2025

Gabriele was a postdoctoral researcher at Caltech, where he explored celestial mechanics, planet formation theory, and the dynamical evolution of the Solar System. His work spans hydrodynamic simulations of protoplanetary disks and analytic modeling of orbital interactions, with the goal of illuminating both early formation and long-term orbital stability in planetary systems. At Caltech, he also pursued advanced studies of the outer Solar System’s structure using numerical modeling techniques. In a 2025 Icarus paper (arXiv:2503.07146), he introduced a quantitative framework that classifies distant Kuiper Belt objects into stable, metastable, and unstable regimes by measuring their orbital diffusion, and demonstrated that (meta)stable objects tend to show stronger orbital clustering in perihelion and pole orientation compared to unstable ones. In 2025, Gabriele moved to the University of Milan as a postdoctoral fellow in the Department of Physics.

Dennis Raush

Caltech undergraduate student (astrophysics) 2020 - 2024

Dennis was broadly interested in computational astrophysics, with past work spanning the effects of dark matter physics on Population III star formation and the role of supernovae in dispersing metals and shaping the first galaxies. In the group, he investigated how the presence of a primordial solar companion could have influenced the early dynamical evolution of the Solar System. His undergraduate research culminated in a paper showing how an early solar binary companion could have enhanced the formation of the inner Oort cloud.

MAX Goldberg

Caltech graduate student (astrophysics) 2019 - 2024

Max was broadly interested in the formation and evolution of extrasolar planetary systems. His doctoral work included a theoretical description of the emergence of intra-system uniformity of exoplanets, as well as a study of long-term tidal evolution in nearly-resonant short-period systems. Max’s previous work considered how masses derived from Kepler transit timing variations could be improved with additional data from the TESS spacecraft. In a 2021 paper, Max identified the first pure 3-body resonance in the exoplanetary census. He went on to quantify the physical processes that shape the architectures of short-period sub-Jovian planets.

After completing his Ph.D. in 2024, Max joined the Observatoire de la Côte d’Azur in Nice as a postdoctoral researcher.

Juliette C. Becker

Caltech 51 Pegasi b postdoc (planetary science/astrophysics) 2019-2023

Juliette was a Heising-Simons Foundation 51 Pegasi b Fellow at Caltech. Her interests range from dynamical characterization of extrasolar planets to discovery of minor bodies in the distant solar system. Together, we worked to understand how the birth environments of planetary systems affect their final dynamical architecture. In this vein, Juliette proposed that Ultra-Short-Period planets are created during FU-Orionis type episodic accretion events. Her full list of publications is available here.

In August 2023, Juliette joined the Department of Astronomy at the University of Wisconsin–Madison as an assistant professor.

Julie inglis

Caltech graduate student (planetary science) 2020 - 2025

Julie used spectroscopy to characterize the atmospheres of giant planets in order to gain insight into their formation and evolution, and was also interested in the formation of satellites around giant planets and their properties. After completing her Ph.D. thesis on giant planets on extreme orbits, she became a postdoctoral researcher at UC San Diego.

Ryleigh Davis

Caltech graduate student (planetary science) 2020 - 2026

Ryleigh has a wide range of research interests from telescopic observations and laboratory work on icy moons to the dynamics and evolution of planetary systems. In the group, she examined tidal dissipation in super-Earths through modeling of planetary systems with significant non-Newtonian contributions to the apsidal precession. After completing her Ph.D. in 2026, she became a postdoctoral researcher at UC San Diego.

Darryl Seligman

University of Chicago TC Chamberlin Postdoctoral Fellow (Geophysical Sciences) 2020 - 2022

Darryl received his Ph.D. from Yale University in 2020, where he worked with Gregory Laughlin and was a Gruber Fellow. He graduated from the University of Pennsylvania in 2015, with degrees in mathematics and physics. He primarily studies theoretical and computational planetary science and astrophysics. He is generally interested in fluid dynamics, nonlinear dynamics, plasma physics and neuroscience. After Chicago, Darryl held an NSF Astronomy and Astrophysics Postdoctoral Fellowship at Cornell, and in 2025 he joined the Department of Physics and Astronomy at Michigan State University as an assistant professor.

Kellen Rodriguez

Caltech undergraduate student (computer science) 2021 - 2022

Kellen was a senior undergraduate student majoring in Computer Science, as well as Business, Economics, and Management, with a minor in Astrophysics. Before joining the group, Kellen did research in bioengineering, working on molecular programming and DNA nanotechnology. He was broadly interested in the formation and evolution of stars and planetary systems.

Marvin Morgan

University of Pennsylvania undergraduate student (physics) 2020 - 2021

As a 4th year undergraduate student at the University of Pennsylvania, Marvin worked on planetary dynamics of the early solar system in the context of the Nice Model. Using N-body simulations we showed how massive planetary embryos can form in the primordial disk of solar system planetesimals, thereby constraining the timing of the giant planet instability. He was broadly interested in solar system dynamics, exoplanetary dynamics, and time domain astronomy. Marvin went on to graduate school at the University of Texas at Austin, working with Brendan Bowler, and continued his Ph.D. at UC Santa Barbara when Bowler’s group moved there.

Walker Melton

Caltech undergraduate student (physics) 2015-2019

As an undergraduate researcher, Walker worked on understanding a correspondence between the secular inclination evolution of razor-thin self-gravitating particle disks and the Schrödinger equation, particularly in the case where long-range coupling in the disk could not be ignored (see published paper here). Walker went on to earn a Ph.D. in physics at Harvard in 2025, studying celestial conformal field theories and the holographic structure of quantum gravity in asymptotically flat and de Sitter spacetimes, and was then named a Junior Fellow of the Harvard Society of Fellows. 

Tobias Koehne

Caltech graduate student (geophysics) 2018-2020

Tobias’ interests centered on applying machine learning methods to seismology. However, during his first year as a graduate student, Tobias worked on delineating how highly inclined trans-Neptunian objects can get injected into the intra-Neptunian solar system, employing large-scale numerical simulations (see published paper here). Tobias went on to complete a Ph.D. in geophysics at Caltech in 2024 and then joined the German Aerospace Center (DLR) as a staff researcher.

Shirui Peng

Caltech graduate student (environmental science and engineering) 2019-2020

Shirui’s interests ranged from seismic ocean thermometry to computational studies of planet formation. Shirui carried out a series of numerical experiments aimed at characterizing the velocity dispersion of planetary building blocks on a detailed level, with an eye towards teasing out aspects of oligarchic growth that can be attributed to simulation artifacts. Shirui’s work showed that even in simulations where self-gravity of a planetesimal swarm is completely suppressed, particle disk excitation can ensue through indirect terms of the governing Hamiltonian. Shirui went on to complete a Ph.D. in environmental science and engineering at Caltech in 2024.

Elizabeth Bailey

Caltech graduate student (planetary science) 2014-2020

Elizabeth first began working with me in 2016. In the first paper she led, she demonstrated that the ~6 degree obliquity of the Sun could in principle have been induced by the gravitational influence of Planet Nine. In her follow-up work, she considered whether or not constraints on Planet Nine’s current on-sky location could be derived from the observational data. Unfortunately, her simulations demonstrated that chaos spoils the feasibility of a resonance-based hunt for Planet Nine. In the latter half of her Ph.D., Elizabeth worked on the now-classic problem of hot Jupiter formation. In this vein, her work has shown that within the framework of the in-situ formation model, the inner boundary of the mass vs. semi-major axis distribution of extrasolar planets should follow a power-law with index -2/7. Intriguingly, this theoretical relationship provides an excellent match to the observational data. In 2020, Elizabeth joined the Department of Astronomy & Astrophysics at UCSC (my alma mater; go slugs!) as a Heising-Simons Foundation 51 Pegasi b Fellow, and in 2025 she joined the faculty of the Department of Earth and Planetary Sciences at the University of Texas at San Antonio.

Chris spalding

Caltech graduate student (planetary science) 2013-2018

While at Caltech, Chris led the development of a theory for the primordial excitation of spin-orbit misalignments in close-in planetary systems. Chris’s work has shown that the entire possible range of misalignments is attainable within the context of the purely gravitational disk-torquing mechanism, and that magnetic disk-star interactions may facilitate the observed correlation between stellar mass and spin-orbit misalignment. Chris has also investigated the connection between physics of disk-star coupling during the embedded phase of star formation and primordial coincidence between stellar and nebular angular momentum vectors, as well as the long-term fate of exo-moons and the origins of the Kepler dichotomy. In 2018, Chris was awarded the 51 Pegasi b Postdoctoral Fellowship by the Heising-Simons Foundation, which he held at Yale University and subsequently at Princeton University.

Maya Fuller

Caltech undergraduate student (astrophysics) 2017-2018

As an undergraduate research fellow, Maya carried out a numerical exploration of the implantation of short-period icy objects into the distant Kuiper belt by Neptune-facilitated outward scattering. Through direct N-body simulations, her work demonstrated that a considerable fraction of presently observed long-period Kuiper belt objects that exhibit rapid chaotic evolution may have been implanted into the distant domain of the solar system comparatively recently (i.e. within the last few hundreds of millions of years), and thus occupy orbits that are largely unaffected by the gravitational effects of putative Planet Nine.

Siteng Fan

Caltech graduate student (planetary science) 2015-2020

Taking advantage of the inherently parallel-computational nature of graphic processing units, Siteng carried out a large suite of self-consistent N-body simulations of the solar system's early dynamical evolution. Our simulations showed that the qualitative picture entailed by the Nice model is insensitive to collective effects of the planetesimal disk and that the coherent structure of the distant Kuiper belt is unlikely to have a self-gravitational origin. After his Ph.D. (2020), Siteng was a postdoctoral scholar at the Laboratoire de Météorologie Dynamique (CNRS) in Paris, and in 2023 he joined the Department of Earth and Space Sciences at the Southern University of Science and Technology (SUSTech) in Shenzhen as an associate professor.

TALIA KHAIN

Caltech undergraduate WAVE fellow (planetary science) 2017

The goal of the research project that Tali undertook was to characterize the evolutionary dependence of the solar system’s trans-Neptunian minor body population on the solar system’s birth environment. In particular, it is widely accepted that the sun and its collection of planets formed in a massive cluster of stars, whose gravitational influence would have had a direct effect upon the distant orbits of icy debris that orbit the sun. To evaluate this effect from quantitative grounds, Tali carried out a series of large-scale computer simulations that elucidated how nascent perturbations upon the solar system from passing stars translate to the dynamical structure of the Kuiper belt we observe today. Tali went on to earn a Ph.D. in physics at the University of Chicago in 2025 and then joined Harvard’s School of Engineering and Applied Sciences as a George F. Carrier Postdoctoral Fellow.

Natalia Storch

Caltech Burke postdoctoral fellow (astronomy) 2015-2018

Natalia was a Sherman Fairchild Postdoctoral Scholar in Theoretical Astrophysics at Caltech’s Burke Institute for Theoretical Physics. Natalia’s work focused on the long-term evolution of extrasolar planetary systems as well as the chaotic dynamics of stellar rotation (see also here). Together, we worked on characterizing a new mode of disk-driven planetary migration, as well as modeling the final stages of planet formation in the solar system. Natalia went on to pursue her life-long passion for writing fantasy and sci-fi novels.

Abhijit Puranam

Caltech undergraduate student (physics) 2014-2017

As an undergraduate research fellow, Abhi was studying the long-term implications of rapid chaotic evolution of planetary systems, using the emblematic Gliese 876 planetary system as a case study. His analysis involved a combination of large-scale numerical N-body simulations and perturbative treatment of stochastic differential equations. Abhi went on to work as a data scientist in Silicon Valley.

Bhawna (mia) Motwani

Caltech graduate student (astrophysics) 2015-2017

While at Caltech, Bhawna studied the physics of planetary migration that occurs during the nebular stage of a planetary system’s lifetime. She employed large-scale magnetohydrodynamical simulations to model the early stages of the solar system’s evolution, with an eye towards constraining the amplitude of turbulent fluctuations within the solar system’s natal disk. Bhawna subsequently continued her doctoral research in computational astrophysics at Columbia University and the Flatiron Institute.

Stephen Markham

Caltech graduate student (planetary science) 2016

When Steve was a first-year graduate student, he and I worked on deriving model-independent constraints on the rates of radial migration of planets in protoplanetary disks. Unlike the conventional approach of modeling this process directly, Steve looked at indirect consequences of radial migration, to obtain observationally grounded estimates of this elusive process. Steve went on to complete a Ph.D. at Caltech on the seismology and cooling of gas giant planets, followed by postdoctoral positions at the Observatoire de la Côte d’Azur and at New Mexico State University as a Tombaugh Scholar.

Katherine Deck

Caltech JCPA fellow (planetary science/astronomy) 2014-2016 

Kat is an expert in the field of orbital dynamics and was a postdoctoral fellow at the Joint Center for Planetary Astronomy at Caltech. She worked on extracting subtle signatures of planet-planet interactions from transit timing variations data, and instigated a description of how planetary systems evolve from their natal configurations to the architectures we observe today. After a period working in data science, Kat returned to Caltech as a research scientist with the Climate Modeling Alliance (CliMA).

Gongjie Li

Harvard graduate student (astrophysics) 2012-2014

Gongjie has revisited the now classic problem of chaotic spin-axis evolution of a putative Moon-less Earth. In doing so, she formulated a purely analytical framework that allowed for an estimation of the characteristic timescale for dynamically-forced climate change and gave an intuitive interpretation of numerical results. Gongjie has extended her results with an aim of quantifying pre-late-heavy-bombardment evolution of the Earth’s obliquity. Gongjie went on to a Junior Fellowship at the Harvard Society of Fellows and joined the School of Physics at Georgia Tech in 2018, where she was promoted to associate professor in 2024.

Juliette Becker

Caltech undergraduate student (astronomy) 2011-2013

Juliette and I worked on understanding the coupling between the planetary interior structure and the orbital state that arises for giant planets that reside in extreme proximity to their host stars. Using the HAT-P-13 system as an illustrative example, Juliette showed that in multi-planet systems that harbor a hot Jupiter, precise characterization of the system's orbital state can yield meaningful constraints on the transiting planet's interior structure, and such a calculation is applicable to an extensive range of orbital architectures. After completing her undergraduate degree, Juliette went on to pursue a Ph.D. in Astronomy at University of Michigan.

Hayden Betts

Polytechnic High School student, summer 2011

Along with Mike Brown and myself, Hayden worked on quantifying the possibility of the existence of an additional ice giant planet in the primordial Solar System. Our study included a large-scale numerical exploration of instability-driven dynamical evolution and showed that indeed, the Solar System may have harbored an additional massive object early on. Our findings were published here. Upon graduating from high school, Hayden enrolled into Harvard University as an undergraduate.