AAS 197, January 2001
Session 70. The Formation, Evolution and Detection of Habitable Planets
Special Session Oral, Tuesday, January 9, 2001, 8:00pm, San Diego

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[70.01] Habitable Planets: Observational Arguments

G. Marcy (UC Berkeley), R.P. Butler (DTM, Carnegie Inst. of Washington), S.S. Vogt (UCO/Lick and DTM, Carnegie Inst. of Washington), D.A. Fischer (UC Berkeley)

Observations of extrasolar planets and protostellar disks suggest that rocky worlds form commonly around young stars. At least 8% of stars are observed to have saturn- and jupiter-mass planets within 3 AU, and more planets are likely beyond 3 AU. The mass distribution of planets rises steeply with decreasing mass (Marcy & Butler 2000), implying that more small planets form than giant ones. Elliptical, rather than circular, orbits predominate among the 35 known planets beyond 0.2 AU. New Doppler and astrometric techniques may reveal planets having masses as low as 10 Earth-masses.

Protoplanetary disks surround over half of young stars, with disk masses typically over 10X that of Jupiter. Their energy distributions from IR and mm-wave observations yield dust emissivities that imply the rapid growth (within 0.1 Myr) of dust particles to millimeter size. Thus, theoretical predictions of quick growth of rocky planets is supported. One may rationally estimate that 50% of all stars form with a retinue of rocky orbiting bodies.

However, a nemesis looms for the survival of earths: dynamical scattering and ejection. The ubiquity of eccentric orbits among jupiters orbiting from 0.2--3 AU suggests that gravitational scattering among planets and planetesimals is a common phenomenon (see the following presentation by H. Levison). If so, the circular orbits and survival of the lowest mass, terrestrial planets are jeopardized. We acknowledge funding from NASA, NSF, and Sun Microsystems.

If you would like more information about this abstract, please follow the link to http://www.exoplanets.org. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

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