My name is Fei Dai (戴飞). I'm a postdoctoral fellow in the Division of Geological and Planetary Sciences at Caltech. I obtained my PhD in Physics from MIT under the supervision of Prof. Josh Winn.

Using both novel data analysis techniques and numerical simulations, I strive to understand the most unexpected outcomes of planet formation, such as the "ultra-short-periods" and the "super-puffs" (see Research Highlights). The mere existence of these planets is puzzling, while they provide a unique opportunity to study critical processes in planet formation and evolution that may be too weak or too slow to be observable on other planets.

On the right is a picture of me at Salar de Uyuni, Bolivia.

Research Highlights

  • The Ultra-Short-Period: hellish worlds that orbit their host stars with periods as short as a few hours.

  • Puzzling lowest-mean-density planets that should not exist.

  • Exotic Planets that orbit their host stars on polar or even retrograde orbits.

  • Starspots leave photometric signatures in planetary transit light curves which can unveil the stellar obliquity and magnetic activity of the host stars.

  • We extended the study of planet radius distribution (Fulton et al 2018) from Sun-like stars to M-dwarf planets. Results suggests that photoevaporation rather than core-powered mass loss is the main driver for the observed radius gap.

  • We studied the process of photoevaporation (proposed to be responsible for the planet radius gap, see left) with hydrodynamic simulations and self-consistent heating and cooling.

  • K2, the second phase of the NASA Kepler mission, enabled us to discover many exciting planetary systems along the ecliptic.

  • A pair of young stars that likely underwent close encounters, a scenario that may explain the observed optical dimming, the tidal arms seen in the millimeter, and a strong Fe emission in X-ray.


  • 84 All Publications
  • 12 First-Authored
  • 1912 Citations
  • 26 h-index
  • 50 i10-index

More up-to-date publication lists can be found here:

Community Service and Outreach

  • A free online workshop for undergraduate students aspiring to become an astronomer.

  • Check out some public talks I gave recently both in English and Mandarin Chinese.

  • I am a mentor for the Caltech WAVE Program: an undergraduate research program for underrepresented minority students.

Brief Bio

I was a graduate student at MIT Department of Physics from 2014 to 2019. I was also a visiting student at Princeton Univerity (2017-2019). Previously, I received B.A. in Natural Science and M.Sci in Physics from the University of Cambridge in 2014 with First Class Honours.