# Frederic A. Rasio
Frederic A. Rasio (also published as F. A. Rasio) is a Belgian-born theoretical and computational astrophysicist who studies the long-term dynamics of gravitational N-body (system of many bodies interacting through gravity) systems, from planetary systems to dense star clusters. He is the Joseph Cummings Professor of Physics at [Northwestern University](https://www.edgepedia.org/northwestern-university) and was a founding co-director of Northwestern's Center for Interdisciplinary Exploration and Research in [Astrophysics](https://www.edgepedia.org/astrophysics) (CIERA).[1](https://www.amacad.org/person/fred-rasio) • [2](https://bpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/9/7460/files/2024/12/CV_2019.html) He is known for work on dynamical instability as a shaper of planetary systems, including a 1996 *Science* paper on the formation of eccentric extrasolar planets and a 2005 *Nature* paper explaining the eccentric orbits of the planets around [Upsilon Andromedae](https://www.edgepedia.org/upsilon-andromedae) by planet–planet scattering.[3](https://ar5iv.labs.arxiv.org/html/astro-ph/0502441)
| Fact | Detail |
|---|---|
| Field | Theoretical and computational astrophysics: planetary-system dynamics, dense stellar systems, gravitational-wave sources[1](https://www.amacad.org/person/fred-rasio) |
| Signature work | "Dynamical Instabilities and the Formation of Extrasolar Planetary Systems", *Science*, 1996 |
| Honors | APS Fellow 2006; Brouwer Career Award 2019; American Academy of Arts and Sciences, 2025, per the American Academy of Arts and Sciences |[2](https://bpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/9/7460/files/2024/12/CV_2019.html) • [5](https://physics.northwestern.edu/people/faculty/core-faculty/frederic-rasio.html) • [1](https://www.amacad.org/person/fred-rasio)
## Education and career
Rasio's own curriculum vitae lists [Stuart L. Shapiro](https://www.edgepedia.org/stuart-l-shapiro) as thesis advisor; the American Astronomical Society's Astronomy Genealogy Project records both Shapiro and [Saul A. Teukolsky](https://www.edgepedia.org/saul-a-teukolsky) as advisors.[2](https://bpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/9/7460/files/2024/12/CV_2019.html) • [6](https://astrogen.aas.org/front/searchdetails.php?agnumber=11705)
## Representative work
Cornell's [Chronicle](https://www.edgepedia.org/chronicle) reported the work in November 1996, when Rasio was an MIT assistant professor, describing it as proposing violent, instability-driven beginnings for the newly discovered Jupiter-sized planets.[7](https://news.cornell.edu/stories/1996/11-3)
The 2005 *Nature* paper applied this picture to Upsilon Andromedae, a star with three known giant planets. It argued the planets began on nearly circular orbits, and that chaotic evolution then perturbed the outer planet into a high-eccentricity orbit; in the simulations, after roughly a thousand years of strongly chaotic evolution the outermost planet is ejected, leaving a two-planet system resembling the one observed.[3](https://ar5iv.labs.arxiv.org/html/astro-ph/0502441) The model also reproduced a distinctive observed detail: the inner eccentric planet returns to a nearly circular state every 9,000 years.[3](https://ar5iv.labs.arxiv.org/html/astro-ph/0502441)
## Research program
Rasio's research spans exoplanets and planet formation; the dynamics of dense stellar systems such as globular clusters, galactic nuclei, and young star clusters; hydrodynamic stellar interactions; and relativistic astrophysics.[5](https://physics.northwestern.edu/people/faculty/core-faculty/frederic-rasio.html) His methods include [Monte Carlo](https://www.edgepedia.org/monte-carlo) cluster simulations, N-body integration, and numerical hydrodynamics, the latter reaching back to his doctoral work on stellar interactions.[2](https://bpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/9/7460/files/2024/12/CV_2019.html) His most recent focus, per his department page, is on tightly packed planetary systems, gravitational-wave sources for the LIGO and LISA detectors, and the formation of massive black holes through stellar-dynamical processes.[5](https://physics.northwestern.edu/people/faculty/core-faculty/frederic-rasio.html)
The disk picture and the instability picture connect in his group's later work. A 2010 *Astrophysical Journal* study co-authored by Rasio used a hybrid N-body and gas-disk code to follow three-planet systems through the dissipation of their gas disk, finding that the distribution of orbital distances is largely set within the gas disk while the distribution of eccentricities is set by planet–planet interactions after the disk dissipates.[8](https://iopscience.iop.org/article/10.1088/0004-637X/714/1/194) In the dense-cluster domain, a 2015 *Physical Review Letters* paper on binary black hole mergers from globular clusters laid out implications for Advanced LIGO's detections.[9](https://doi.org/10.1103/physrevlett.115.051101)
## Role at CIERA and service
At Northwestern, Rasio was a founding co-director of CIERA and served as its Co-Director from 2009 to 2013.[4](https://aspenphys.org/people/frederic-fred-a-rasio/) • [2](https://bpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/9/7460/files/2024/12/CV_2019.html) In 2013 he became Lead Editor of *The Astrophysical Journal Letters*.[1](https://www.amacad.org/person/fred-rasio) • [2](https://bpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/9/7460/files/2024/12/CV_2019.html)
## Honors
He was elected a Fellow of the [American Physical Society](https://www.edgepedia.org/american-physical-society) in 2006, a Fellow of the AAAS in 2018, received the Brouwer Career Award from the American Astronomical Society in 2019, and was named an AAS Legacy Fellow in 2020.[5](https://physics.northwestern.edu/people/faculty/core-faculty/frederic-rasio.html) On April 23, 2025, the American Academy of Arts and Sciences announced his election in the class covering astronomy, astrophysics, and earth sciences; he was the only Northwestern faculty member in the mathematical and physical sciences among at least seven named from the university that year.[10](https://ciera.northwestern.edu/2025/04/23/fred-rasio-elected-to-american-academy-of-arts-and-sciences/)
## Recent developments
Rasio remains active. His ORCID record lists a 2024 *Astrophysical Journal* paper on intermediate-mass black hole progenitors formed by stellar collisions in dense star clusters, and 2025 *Astrophysical Journal Letters* papers on spin–orbit alignment in merging binary black holes following collisions with massive stars and on accretion-driven origins of massive, highly spinning black holes in dense star clusters.[11](https://orcid.org/0000-0002-7132-418X)
## References
1. [Fred Rasio | American Academy of Arts and Sciences](https://www.amacad.org/person/fred-rasio)
2. [Curriculum Vitae of Frederic A. Rasio](https://bpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/9/7460/files/2024/12/CV_2019.html)
3. [Planet–Planet Scattering in Upsilon Andromedae (Nature, 2005)](https://ar5iv.labs.arxiv.org/html/astro-ph/0502441)
4. [Frederic (Fred) A. Rasio, Aspen Center for Physics](https://aspenphys.org/people/frederic-fred-a-rasio/)
5. [Frederic Rasio: Department of Physics and Astronomy, Northwestern University](https://physics.northwestern.edu/people/faculty/core-faculty/frederic-rasio.html)
6. [AstroGen, The Astronomy Genealogy Project: Frederic Armand Rasio](https://astrogen.aas.org/front/searchdetails.php?agnumber=11705)
7. [Cornell Chronicle (November 1996)](https://news.cornell.edu/stories/1996/11-3)
8. [Unstable Planetary Systems Emerging Out of Gas Disks (ApJ, 2010)](https://iopscience.iop.org/article/10.1088/0004-637X/714/1/194)
9. [Binary Black Hole Mergers from Globular Clusters: Implications for Advanced LIGO (PRL, 2015)](https://doi.org/10.1103/physrevlett.115.051101)
10. [Fred Rasio elected to American Academy of Arts and Sciences, CIERA](https://ciera.northwestern.edu/2025/04/23/fred-rasio-elected-to-american-academy-of-arts-and-sciences/)
11. [Frederic A. Rasio, ORCID](https://orcid.org/0000-0002-7132-418X)
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*Topic: Encyclopedia › Physical world and mathematics › Physical and mathematical scientists › Physicists and astronomers › Researchers in astrophysics, cosmology, and gravitational-wave science › Stellar astrophysics*
*Initially written Sep 21, 2026 · Reviewed: Sep 25, 2026 · Edited: Sep 25, 2026; Oct 11, 2026; Oct 15, 2026 · Last review: Sep 25, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license