Dr. Sheila Sagear
Postdoctoral Researcher · University of Florida
I am a postdoctoral researcher at the University of Florida specializing in exoplanet demographics and Galactic dynamics. I study exoplanets around the smallest and coolest stars, with a focus on orbital eccentricities and how planetary system architectures connect to the broader structure of the Milky Way.
In September 2026, I will begin a Flatiron Research Fellowship in the Center for Computational Astrophysics at the Flatiron Institute.
In the past, I have been a Pre-Doctoral Fellow at the Flatiron Institute, an intern at the Kepler/K2 Guest Observer Office at NASA Ames Research Center, and an intern with the FastML group at CERN.
Research
My research is focused on the orbital dynamics of exoplanets around small stars, asking how eccentricity distributions, Galactic kinematics, and stellar age connect to the formation and evolution of planetary systems.
I am interested in pursuing questions relating to the Galactic history of planets and their host stars:
- Do planets retain knowledge about where they are in the Milky Way, or of their Galactic history?
- How do the broader structure, dynamics, and history of the Milky Way affect the types and numbers of planets that live in it?
- How do the orbital dynamics of planets around their host stars and the Galactic dynamics of stars around the Galactic center interact?
Galactic Dynamics & Planet Demographics
Combining Gaia DR3 astrometry with stellar chemistry from APOGEE, I investigated how planetary eccentricity populations differ between the kinematically thin and thick Galactic disks.
Orbital Eccentricities of M Dwarf Planets
Leveraging the photoeccentric effect with Kepler transit light curves, I constrained eccentricity distributions for planets around nearby M dwarf stars, revealing distinct populations for single and multi-planet systems.
Stellar Age Inference
I developed zoomies, an open-source Python tool to infer stellar ages from vertical action in Gaia data, a mass-independent age-constraining method applicable to stars from supergiants to M dwarfs.
The Eccentricity–Radius Relation for M Dwarf Planets
Using TESS and Kepler transit data, I constrained orbital eccentricities for ~200 planets orbiting M dwarfs. I found a positive eccentricity–radius relationship with elevated eccentricities for planets larger than 3.5 R⊕, mirroring the trend seen around Sun-like stars and offering new clues about late-stage dynamical evolution processes.
Selected Publications
Full list on NASA ADS
-
2026Accepted to The Astronomical Journal
-
2026The Astronomical Journal
-
2024The Astrophysical Journal
-
2023Proceedings of the National Academy of Sciences, 120
-
2020The Astronomical Journal, 160, 19
Selected Presentations
-
2025
-
2025
-
2022
-
2019
Software
github.com/ssagear/zoomies
zoomies is an open-source tool to constrain stellar ages using only kinematic information (vertical action from Gaia), a galactic potential model, and an external stellar calibration sample. The package includes tools to calibrate a stellar age–vertical action relation and apply it to your desired stellar sample. Since the age relation comes from purely kinematic information (Galactic orbits), the relation is nearly completely mass-independent, meaning you can use this tool to constrain ages for any stars from supergiants to M dwarfs!
github.com/lightkurve/lightkurve
Contributor to this user-friendly, open-source Python package for working with Kepler, K2, and TESS data.
Outreach
I am passionate about making astronomy and software skills accessible to early-career researchers. For the past two years I have served as a Teaching Assistant and Head Teaching Assistant for Code/Astro, coordinating the TA team, developing curriculum, leading hands-on coding sessions, and mentoring participants as they build their own open-source astronomy packages.
Contact
