Sagan Postdoctoral Fellowship Recipients

2009 Postdoctoral Fellows

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

JPL press release announcing the 2009 Carl Sagan Fellows

Ian Dobbs-Dixon
University of Washington

Winds and Weather on Worlds Beyond Our Solar System

Ian received his PhD from the University of California, Santa Cruz in June 2006. Since then, he has been working at McGill University in Montreal as a Canadian Institute for Theoretical Astrophyscis (CITA) National Fellow. He is 31-years-old and grew up in northern California.

Ian became interested in planetary science during his first year in graduate school. The emerging field offered exciting opportunities to explore a wide range of scientific disciplines. The need for interdisciplinary research in order to build a thorough, robust understanding of planetary formation and evolution was particularly intriguing.

Ian will use 3-dimensional numerical models to study the flow of fluid and radiation within the atmospheres of short-period planets. More than 15% of the exoplanets discovered to date have orbital periods of 3 days or less. The resulting irradiation from the host star, and that their rotation periods are presumably locked with their orbital period, drives intense weather due to the large, permanent day-night temperature contrast. The tendency of short-period planets to transit their host star allows the extraction of information about the structure, composition, and weather on these planets. Theoretical models allow for the detailed comparison between observation and physical atmospheric processes. In addition, the first Earth-like planets to be detected will likely be orbiting very close to their host star. Ian's research also aims to extend gas-giant models to terrestrial planets to better understand future observations of extrasolar planets.

Subo Dong
Institute for Advanced Study, Princeton

Searching For Extrasolar Planets with Gravitational Microlensing

Subo is a 27-year-old graduate student of astronomy at the Ohio State University. He was born and raised in Hebei Province of China and expects to get his PhD in July 2009.

When first introduced the basic concepts of microlensing, Subo was immediately struck by the elegance of the method itself. At that time, only one planet had been discovered with microlensing, and he became fascinated in working to tap its great potential in exploring extrasolar worlds.

Gravitational microlensing is probing a largely uncharted territory of extrasolar planet discovery, by finding cold rocky planets and extrasolar planetary systems resembling our own. In the next few years, Subo's proposed research will potentially lead to discoveries of a couple dozen new planets, which will offer important clues on how common solar systems like ours are and which has the exciting prospect of detecting extrasolar Earths. In addition, Subo will develop key analysis techniques to be applied to many hundreds of planet discoveries expected from an ambitious microlensing planet survey now under construction. This survey will provide an unprecedented picture of the demographics of exoplanets throughout the Galaxy.

Sasha Hinkley
California Institute of Technology

High-Contrast Integral Field Spectroscopy for Exoplanetary Science

Sasha will receive his PhD in Astronomy from Columbia University in New York City in May, 2009. He's 32-years-old and grew up in Boulder, Colorado.

Sasha has always been interested in how relatively new techniques like adaptive optics and coronagraphy can uncover the amazing environments in close proximity to nearby stars. "We are in a truly exciting time in astronomy where we're going to begin to start studying planets in solar systems other than our own" he said.

Sasha will carry out a high-contrast imaging survey on the Palomar 200-inch telescope with the goal of detecting and obtaining spectra for extrasolar planets. Such spectra will allow him to address questions about planets' atmospheres, physics and thermochemistry. This survey, over 120 nights, will use a newly commissioned coronagraph and integral field spectrograph (IFS) he built as part of his PhD thesis. This instrument, along with a Lyot coronagraph, is the basis for a long-term, high-contrast imaging program recently begun at Palomar. Using speckle suppression techniques afforded by the IFS, he plans to obtain spectra from 1.0 to 1.8 microns (resolution ~ 30-100), of planets into the Jovian mass regime. His Sagan Fellowship will be comprised of three phases: 1) the initial survey for warm/massive planets or brown dwarfs, 2) a planned upgrade to the instrument in 2010 and 3) the Key Project portion which will obtain spectra of exoplanets around the brighter stars in the survey.

Stefan Kraus
University of Michigan

Exploring the potential planet-forming regions in young stellar disks with infrared interferometry

Stefan received his PhD in June 2007 from the University of Bonn, Germany. He is 31-years-old.

During his earlier work on infrared interferometry, Stefan became fascinated by the opportunities that this technique offers for studying circumstellar disks around young stars. Stefan finds it intriguing that infrared interferometry already enables us to investigate the disk structure in the terrestrial planet forming zone where planetary systems are just forming. In particular, we are entering an era where direct interferometric imaging of inner disk regions becomes feasible, which will be the key to ultimately revealing the signatures that the orbiting protoplanets impose on the disk structure.

Providing the material and the site for planet formation, circumstellar disks around young stars play a central role in the formation process and evolution of planetary systems. The aim of this project is to employ the unique spatial resolution provided by CHARA and Keck infrared interferometry to characterize the structure and physical conditions of the disk in the inner-most AU. Furthermore, we aim to obtain the first model-independent aperture synthesis images of low- and intermediate-mass stars, revealing the fundamental morphology and maybe disk substructure of the inner, potentially planet-forming zone.

Eliza Kempton (formerly Miller-Ricci)
University of California, Santa Cruz

Theoretical Models of Extrasolar Super-Earth Atmospheres

Eliza is 27-years-old and will receive her PhD from Harvard University in June 2009. She grew up in Newton, MA, just outside Boston.

In high school, Eliza was excited to learn about the discoveries of the first extrasolar planets, and today our planet-finding abilities have advanced to the point that we are on brink of discovering the first Earthlike exoplanet. The atmospheres of exoplanets will likely provide the first clues of what the conditions are on the surfaces of these planets - whether these planets host extraterrestrial life, whether humans could possibly visit these planets in the future, and whether we could withstand the temperatures on these planets or breathe their air.

Eliza will use theoretical models to study the atmospheres of extrasolar super-Earths (planets with masses in the range of one to 10 Earth masses). In particular, she is interested in studying the effects of photochemistry and clouds on the atmospheric structure and composition. Eliza plans to model a wide variety of possible super-Earth atmospheres, including atmospheres that may differ dramatically from the planetary atmospheres found in our own Solar System.