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2005–2006 Lectures in the Sciences

Photo by Jason Doiy

The past decade ushered in a new era in astronomy as planets orbiting nearby stars were finally detected. The ensemble of extrasolar planets now numbers almost 200 and displays a startling diversity of characteristics. The orbital parameters of these planets have helped astronomers to understand how these objects formed. Studies of the host stars reveal the types of environments that enhance the formation of gas giant planets like our Jupiter. Simulations of planet formation and models of subsequent dynamical interactions are now beginning to reproduce the observed distribution of planet characteristics. This talk will review current paradigms for planet formation and early evolution and will highlight key characteristics of detected exoplanets that have helped to test theoretical models.

Thursday, February 16
4:15 p.m.
Lecture Hall A in Science Center
1 Oxford Street, Cambridge, Massachusetts
For more information, call 617-495-8600

This lecture is designed for the scientifically interested layperson and is free and open to the public. This event is cosponsored by the Harvard-Smithsonian Center for Astrophysics.

Debra Fischer received her PhD from the University of California at Santa Cruz in 1998. She completed a postdoctoral fellowship at the University of California at Berkeley, and she is currently an associate professor of astronomy at San Francisco State University. Fischer is the project scientist for the Lick Observatory planet search program and for a dedicated robotic telescope that will be commissioned in April 2006. She is also program scientist for a Key Science Project to find earth-mass planets using the Space Interferometry Mission. Fischer has participated in the discovery of more than 100 extrasolar planets, and she now leads an international consortium using the Keck, Subaru, and Magellan telescopes to search for short-period planets. Such planets have a high probability of transiting their host stars and thereby revealing their size, structure, and atmospheric constituents. One surprising discovery from this new survey is a transiting saturn-mass planet with a 70 earth-mass core of heavy elements (Sato, Fischer, Henry et. al, 2005). Fischer recently characterized the chemical composition and properties of more than 1500 stars on current Doppler planet surveys, quantifying a correlation between iron abundance and the formation of gas giant planets (Fischer & Valenti, 2005). Recent work suggests that alpha-elements (e.g., silicon and oxygen) may be even stronger indicators of extrasolar planet formation and points to core accretion as the formation mechanism for detected extrasolar planets.