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<TITLE>Two planetary talks on Monday, October 17: Selsis and Jayawardhana</TITLE>
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<P><FONT SIZE=2 FACE="Arial">Astrobiology Lecture Series</FONT>
<BR><FONT SIZE=2 FACE="Arial">Franck Selsis (CRAL-Ecole Normale Superieure)<BR>
<BR>
Date: Oct. 17, 2005 (Monday), at 12:30PM<BR>
Place: Pratt Conference Room, Center for Astrophysics,<BR>
60 Garden Street (<U></U></FONT><U><FONT COLOR="#0000FF" SIZE=2 FACE="Arial"><A HREF="http://cfa-www.harvard.edu/mapsdir.html">http://cfa-www.harvard.edu/mapsdir.html</A></FONT></U><FONT SIZE=2 FACE="Arial">) </FONT>
<BR><FONT SIZE=2 FACE="Arial">Title: Planetary science with Darwin and TPF </FONT>
<BR><FONT SIZE=2 FACE="Arial">Abstract: </FONT>
<BR><FONT SIZE=2 FACE="Arial">The future space observatories Darwin (IR interferometer, ESA) and<BR>
TPF-C (Optical coronograph, NASA) will lead to a major leap in the<BR>
understanding of terrestrial planet formation, the evolution of their<BR>
atmosphere and their habitability. Most of our present knowledge in<BR>
this field comes from the comparison of Mars, The Earth and Venus.<BR>
Solar system studies have resulted in great advances, like the concept<BR>
of habitable zone, but have also let unsolved questions: was the<BR>
divergent<BR>
evolution of these three planets only due to their orbital distance and<BR>
mass or also to important initial differences in their water and<BR>
volatile composition ? What were the physical and chemical conditions<BR>
prevailing in the earliest stages of these planets ? Although in situ<BR>
exploration will certainly provide new clues, the possibility to study<BR>
a larger diversity of terrestrial planets, at different ages and<BR>
orbiting various types of stars will clearly open a new area in<BR>
planetary science.<BR>
<BR>
Beyond the challenging planet detection itself, the goal of Darwin and<BR>
TPF is to characterize some of the properties of terrestial exoplanets.<BR>
Light curves will allow us to distinguish between airless bodies and<BR>
planets with dense atmospheres. Low-resolution spectra will give us<BR>
access to the radius of some planets, their brightness temperature,<BR>
their albedo. Spectroscopy will also reveal the presence of atmospheric<BR>
species which, together with the radiative budget of the planet, will<BR>
provide the keys to understand how the climate system works there.<BR>
Temperature and size retrieval together with the search for H2O and CO2<BR>
will make possible for observers to address the question of<BR>
habitability. As an exciting but uncertain perspective, some planetary<BR>
spectra might also exhibit indicators of biological activity.<BR>
Eventually, the observation of young systems (less than 1 Gyr old) will<BR>
provide us new insights on the early history of our own planet, and new<BR>
constraints on the nature of primitive environments and, indirectly, on<BR>
our origins.<BR>
<BR>
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<P><FONT SIZE=2 FACE="Arial">Radcliffe Institute's </FONT><A HREF="http://www.radcliffe.edu/events/lectures/2005_jayawardhana.php"><U><FONT COLOR="#0000FF" SIZE=2 FACE="Arial">DEAN’S LECTURE SERIES</FONT></U></A><BR>
<FONT SIZE=2 FACE="Arial">Ray Jayawardhana<BR>
“New Worlds in the Making: Origins of Planets and Brown Dwarfs”<BR>
Monday October 17, 4:15 p.m.<BR>
Lecture Hall A, Harvard Science Center</FONT>
<BR><FONT SIZE=2 FACE="Arial">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. </FONT></P>
<P><FONT SIZE=2 FACE="Arial">Until recently, we knew of only one planetary system: our own. Ending centuries of speculation, astronomers have detected nearly 150 planets around other sun-like stars during the past decade. Over the same period, they have also discovered hundreds more so-called brown dwarfs, which are too puny to light up as stars but do not fit the traditional definition of planets. Intriguingly, some brown dwarfs may harbor planetary companions. The apparent ubiquity of both planets and brown dwarfs begs the question of their origins. Jayawardhana will report on how astronomers are deciphering the birth and early evolution of planets and brown dwarfs using a combination of remarkable new observations and sophisticated computer simulations.</FONT></P>
<P><FONT SIZE=2 FACE="Arial">Ray Jayawardhana is an associate professor of astronomy and astrophysics at the University of Toronto and an internationally known science writer. He holds a bachelor's degree from Yale and a PhD from Harvard. He has also performed research and taught at the University of California at Berkeley and the University of Michigan. He uses some of the world's largest telescopes</FONT><FONT SIZE=2 FACE="Tahoma">–</FONT><FONT SIZE=2 FACE="Arial">including Keck, Gemini, VLT, and Magellan</FONT><FONT SIZE=2 FACE="Tahoma">–</FONT><FONT SIZE=2 FACE="Arial">to explore the origins and diversity of planetary systems as well as the formation of stars and brown dwarfs. He is the author or coauthor of more than forty scientific papers and coeditor of two volumes of conference proceedings. Jayawardhana serves as a contributing editor to Astronomy magazine, and his popular articles have appeared in a variety of other publications, including The Economist, Science, New Scientist, Scientific American, and Sky & Telescope. He is the recipient of the 2003 Science Writing Award for a Scientist from the American Institute of Physics and is the author of Star Factories: The Birth of Stars and Planets (Steck-Vaughn/Harcourt, 2000).</FONT></P>
<P><FONT SIZE=2 FACE="Arial">Map: </FONT><A HREF="http://map.harvard.edu/level3.cfm?mapname=camb_allston&tile=F7&quadrant=B&series=NW"><U><FONT COLOR="#0000FF" SIZE=2 FACE="Arial">http://map.harvard.edu/level3.cfm?mapname=camb_allston&tile=F7&quadrant=B&series=NW</FONT></U></A>
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