Sagan Postdoctoral Fellowship Recipients

2012 Postdoctoral Fellows

for additional information on each Fellow's project, please click on the project title

JPL press release announcing the 2012 Carl Sagan Fellows

Sarah Ballard
University of Washington

Investigating Habitable Worlds: Validating and Characterizing Kepler-Identified Planet Candidates around M Dwarf Stars

Sarah will receive her PhD from Harvard University in May 2012. She is 27 years old, and grew up in the San Francisco Bay Area.

As a freshman college student at Berkeley, Sarah firmly believed she would major in Peace and Conflict Studies or Gender Studies. It was only after taking an astronomy class to fulfill a physical science requirement that she realized her natural passion for the field. There was a single moment in this class, which Sarah never would have taken if it were not required, in which she had a jaw-dropping revelation about the incredible, unfathomable scale of the universe.

Sarah will combine observations of transits, gathered with both Kepler and Warm Spitzer, to validate the authentic planetary nature of a subset of Kepler candidate exoplanets. In particular, she will study super-Earth-sized exoplanets in the habitable zones of M stars. In order to characterize these stars, whose spectra are so different from that of our sun, she will conduct a ground-based campaign to gather their near-infrared spectra.

Jean-Michel Desert
California Institute of Technology

Exploring the Plurality of New Worlds

I received my PhD in astrophysics at the Institut d'Astrophysique de Paris (IAP), University of Paris VI (Pierre & Marie Curie) in 2009.

I grew up in the French Anjou's countryside, surrounded by the Loire Valley's vineyards, which left me with a sense of wonder for the vast night skies. I was fascinated by the idea that Earth siblings could potentially exist and could be discovered. As a young teenager, I decided to explore the Universe by building my own telescope. I quickly discovered the challenges that lie behind astronomical instrumentation, which made me even more appreciative of the skies that were subsequently revealed to me. Astronomy, in particular exoplanetary science, became the focus of my future studies and research.

I aim to study the architecture of planetary systems around nearby stars through the observation of their atmospheres. I will conduct a comprehensive comparative exoplanetology program using ground and space-based telescopes. This will be accomplished by probing exoplanet atmospheres in order to obtain their spectra, which will in turn allow us to address questions on their composition and their diversity. Such observations will provide a powerful insight into the formation and evolution of planetary systems in general. It will also enhance our understanding of our own Solar System's formation, one of the most fundamental questions in astrophysics.

Catherine Espaillat
Harvard-Smithsonian Center for Astrophysics

Towards a Multi-Wavelength View of Planet-Forming Circumstellar Disks

Catherine Espaillat grew up in New York City and is 30 years old. She received her Ph.D. from the University of Michigan in 2009. She was then a National Science Foundation Astronomy and Astrophysics Postdoctoral Fellow.

Catherine's interest in astronomy began at a young age, mainly due to the combination of an underwhelming, metropolitan night sky and influential media. When she looked up at the stars from her yard in Queens, she didn't see much. However on PBS, she learned that the sky was full of galaxies, stars, and planets. Determined to see what was really out there, she saved up and bought a telescope. She excitedly set it up on her front porch the night she bought it, pointed it a bright star, and was disappointed to find nothing impressive. Throughly disappointed, she promptly returned the telescope the next day, bought some CDs instead, and turned her thoughts to medicine.

During her undergraduate studies at Columbia University, Catherine's interest in astronomy was rekindled with an introductory course and she left medicine behind. Catherine became fascinated by planets and was drawn to understanding how planets form. In particular, her research focuses on characterizing the observable properties of planet-disk interactions in the planet's nascent stages. Disks around newborn stars evolve from initially well-mixed distributions of gas and dust to systems composed mostly of rocky planets and gas giants like our own solar system. Forming planets will interact with the disk, clearing the material around themselves and leaving behind observable signatures in the disk in the form of gaps. Catherine is pursuing a multi-wavelength analysis of these planet-forming disks (with telescopes much more powerful than the first one she ever used) and thinks that understanding how planets originate and clear their surrounding environment will help us identify those disks that are undergoing the incipient stages of planet formation.

Nikole Lewis
Massachusetts Institute of Technology

Chemistry of Exoplanet Atmospheres: Linking Three-Dimensional Chemical, Dynamical and Radiative Processes

Nikole will receive her PhD in planetary sciences from the University of Arizona in May 2012. She grew up in Lafayette, IN before heading to Worcester Polytechnic Institute to earn a bachelors degree in mechanical engineering and physics. After continuing on to earn a masters degree in astronomy from Boston University, Nikole spent a few years working in industry as a systems engineer before deciding to pursue a doctorate in planetary sciences. She is 32 years old and lives with her husband and daughter in the Boston area.

Nikole has had an interest in all things space-related since grade school. Her work at the University of Arizona with exoplanet atmospheric models has provided the perfect outlet for her diverse background. Nikole is especially interested in characterizing exoplanet atmospheres by combining information from observations and theoretical models. She hopes that through her research efforts we will better understand the physical processes at work in the atmospheres of planets outside of our solar system.

As a Sagan Fellow at the Massachusetts Institute of Technology, Nikole will use sophisticated three-dimensional atmospheric models to explore the interplay between dynamical, radiative and chemical processes in exoplanet atmospheres. She will investigate the impact of disequilibrium chemistry, carbon-rich/poor atmospheric abundances, and clouds on exoplanet global scale winds, thermal patterns, and observable flux variations. The goal of this project is to aid in the interpretation of observations aimed at the characterization of exoplanet atmospheres, which have already revealed a great diversity in exoplanet atmospheric chemistry.

Rebecca Martin
University of Colorado

Accretion and Planetary System Formation

I am 29 years old. I grew up in Leicestershire, in the English countryside. I completed all of my degrees during 8 years at the University of Cambridge. I received my PhD in 2009 from the Institute of Astronomy. Since then I have been a Giacconi Fellow at the Space Telescope Science Institute in Baltimore.

Planets are thought to form within a protoplanetary disc around a young star. Satellites ("moons") form within a circumplanetary disc. Understanding angular momentum transport in these accretion discs is fundamental to explaining the formation of planetary and satellite systems and their survival after the disc has dispersed. I use analytic and numerical methods in gas dynamics to study the theory of these processes. By studying extrasolar systems that can be very different to our own, we both challenge and improve on the theory of planet formation and move towards an understanding of where we came from and evidence for life elsewhere.

Christian Schwab
Yale University

Extreme Precision Doppler Spectrographs

Christian grew up in the countryside near Frankfurt, Germany. He is 32 years old, and received his PhD from the University of Heidelberg in 2010.

Chris has been interested in astronomy all his life, spending countless nights outside with a small telescope and reading every astronomy book he could get his hands on. He still remembers the thrill of seeing Saturn for the first time at the local observatory. Yet, astronomy had always been a pastime, while his research in university focused on optics. After a Master's thesis on laser optics, he took the chance to combine his interests in a PhD thesis on calibration optics for laser guide stars at the Large Binocular Telescope. During this time, he started studying exoplanets. "My group was carrying out a Doppler planet search at Lick observatory, and I spent a lot of time observing. This is when I became aware of the intricacies of spectrographs for radial velocity programs". He was intrigued by the extreme precision necessary to detect earth-like planets. With his background in optics, Chris wants to apply new methods, and lever the achievements in photonics to tackle some of the problems of reaching cm/s Doppler precision. During his Sagan fellowship, he will combine astrophotonics and adaptive optics to develop a new spectrograph concept for extreme Doppler precision.