[Baps] Two planetary talks on Monday, October 17: Selsis and Jayawardhana

[Sarah T. Stewart-Mukhopadhyay]

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Astrobiology Lecture Series
Franck Selsis (CRAL-Ecole Normale Superieure)

Date: Oct. 17, 2005 (Monday), at 12:30PM 
Place: Pratt Conference Room, Center for Astrophysics,
60 Garden Street (http://cfa-www.harvard.edu/mapsdir.html) 
Title: Planetary science with Darwin and TPF 
Abstract: 
The future space observatories Darwin (IR interferometer, ESA) and 
TPF-C (Optical coronograph, NASA) will lead to a major leap in the 
understanding of terrestrial planet formation, the evolution of their 
atmosphere and their habitability. Most of our present knowledge in 
this field comes from the comparison of Mars, The Earth and Venus. 
Solar system studies have resulted in great advances, like the concept 
of habitable zone, but have also let unsolved questions: was the 
divergent
evolution of these three planets only due to their orbital distance and 
mass or also to important initial differences in their water and 
volatile composition ? What were the physical and chemical conditions 
prevailing in the earliest stages of these planets ? Although in situ 
exploration will certainly provide new clues, the possibility to study 
a larger diversity of terrestrial planets, at different ages and 
orbiting various types of stars will clearly open a new area in 
planetary science.

Beyond the challenging planet detection itself, the goal of Darwin and 
TPF is to characterize some of the properties of terrestial exoplanets. 
Light curves will allow us to distinguish between airless bodies and 
planets with dense atmospheres. Low-resolution spectra will give us 
access to the radius of some planets, their brightness temperature, 
their albedo. Spectroscopy will also reveal the presence of atmospheric 
species which, together with the radiative budget of the planet, will 
provide the keys to understand how the climate system works there. 
Temperature and size retrieval together with the search for H2O and CO2 
will make possible for observers to address the question of 
habitability. As an exciting but uncertain perspective, some planetary 
spectra might also exhibit indicators of biological activity. 
Eventually, the observation of young systems (less than 1 Gyr old) will 
provide us new insights on the early history of our own planet, and new 
constraints on the nature of primitive environments and, indirectly, on 
our origins.

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Radcliffe Institute's DEAN'S LECTURE SERIES
<http://www.radcliffe.edu/events/lectures/2005_jayawardhana.php> 
Ray Jayawardhana
"New Worlds in the Making: Origins of Planets and Brown Dwarfs"
Monday October 17, 4:15 p.m.
Lecture Hall A, Harvard Science Center
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. 
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.
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-including Keck, Gemini, VLT, and Magellan-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).
Map:
http://map.harvard.edu/level3.cfm?mapname=camb_allston&tile=F7&quadrant=B&se
ries=NW

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