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Planetary Astrophysics


A View of the Earth in Quadrature

“I should disclose and publish to the world the occasion of discovering and observing four Planets, never seen from the beginning of the world up to our own times, their positions, and the observations... about their movements and their changes of magnitude”

--- Galileo Galilei (March 1610) on his discovery, in the previous year, of the moons of Jupiter.


Four hundred years after Galileo’s discoveries via the first astronomical use of the telescope, the world’s astronomers are once again using powerful new instrumentation to make startling discoveries of and about new planets, quite literally other worlds. This work not only drives the rapid growth of a major new research field but also promises to once again transform our understanding of the nature of the Earth and of life’s and humanity’s places in the cosmos. Over the past decade the study of both extrasolar and Solar System planets has thus become one of the most active research areas at Princeton, with projects that span the full range from development of new instrumentation through large and small observational studies to theoretical investigations.

Princeton is leading the HATNet and HATSouth transiting extrasolar planet search projects. HATNet consists of 6 small, wide-field, fully robotic telescopes, which have been operational since 2003 -- making it the longest operating robotic telescope network. Through the so-called transit method, these telescopes have discovered close to 60 transiting extrasolar planets. Many of these were first of their kind, e.g. the only exo-Neptunes found by a wide-field ground-based survey (HAT-P-11b, -26b), one of the first planets orbiting opposite to the host star's spin (HAT-P-7b), the first super-Jupiter with an accurate mass and radius measurement (-2b), the first hot Jupiter with an outer companion with a well-determined orbit (-13b), and some of the largest known planets (-32b, -33b).

HATSouth is a global network of fully automated identical wide-field  telescopes. It is the first such ground-based network that is capable of year-round 24 hour monitoring of positions over an entire hemisphere of the sky. HATSouth employs six telescope mounts (each hosting 4 optical tubes), spread over three prime locations with large longitude separation in the  southern hemisphere (Las Campanas Observatory, Chile; HESS site, Namibia; Siding Spring Observatory, Australia. The project is run in collaboration with the Australian National University, the Max-Planck-Institute for Astronomy, and Pontificia Universidad Catolica de Chile. Through this facility we have discovered 17 exoplanets, including the longest period planet found by a ground-based transit survey, and one of the only Saturn-sized planets around a cool star. HATSouth is uniquely capable of discovering long period transiting planets from the ground. 

Prof. Bakos' team at Princeton consists of researchers Dr. Joel Hartman (characterization of planetary systems, time-series analysis), Dr. Kaloyan Penev (photometric methods, data analysis pipeline, tidal evolution of planets), Dr. Waqas Bhatti (photometric methods, time-series data analysis), Dr. Miguel de Val-Borro (technical staff, tracking of planet candidates), Zoltán Csubry (technical staff, hardware programming, data analysis pipelines).

Princeton is leading the future HATPI project. HATPI will be a unique scientific instrument, which will continuously image the entire night  sky above 30 arcdegrees elevation (corresponding to 1pi solid angle, or a quarter of the celestial sphere) at moderately high spatial resolution (23"/pixel), high time resolution (30 seconds), and ultra high photometric precision (reaching 2 mmag per point), for an extended duration of >5 years. HATPI will be a wide field mosaic camera system, using a " hedgehog" formation of multiple lenses and CCDs, all placed on a single custom-developed mount. The key science theme of HATPI will be transiting exoplanets; long period and/or small radius planets, transiting bright/nearby stars. It will substantially extend the yield of the TESS space mission. No other current or upcoming survey has significant sensitivity to the long period planets which will be prime targets for detailed characterization with JWST and 30-m telescopes.

The Princeton team is also leading the effort of the analysis of the full frames of the future Transiting Extrasolar Planet Survey Satellite (TESS) space mission. This will yield thousands of short period transiting exoplanets around moderately bright stars on the entire sky.

Jeremy Kasdin and Robert Vanderbei are working with both theorists and observers in the Department to develop optical systems for high contrast imaging, for space- and ground-based applications, via both design studies and laboratory experimentation. Department postdoctoral fellows and graduate students are extensively and deeply involved in all of these research efforts.

On the theory side, Adam Burrows works extensively on the modeling of exoplanetary atmospheres and their evolution, with a strong orientation towards the interpretation of the rising flood of new data on these diverse objects. Jeremy Goodman and Scott Tremaine work on fundamental dynamical problems in a variety of contexts, including both Solar System and exoplanet ones. Christopher Chyba's interests are directed towards understanding the complex and often startling properties of icy moons in the outer Solar System. David Spergel works on problems in theoretical optics associated with ultra high-contrast imaging systems that are needed for the study of exoplanets.

Department Faculty Members With Major Planet Research Interests: