Cool Stars 14 - Submitted Abstract # 332
This version created on 05 October 2006

Gravitational Microlensing Observations Indicate that Cool,
Super-Earth Mass Planets are Common


David P. Bennett, University of Notre Dame
MOA for the PLANET, OGLE and MicroFUN Collaborations

Gravitational microlensing planet search surveys are sensitive to
planets in orbits at a separations of 1-5 AU about the randomly
selected lens stars for gravitational microlensing events observed
toward the Galactic bulge.  Two of the four extrasolar planets
detected by this method have a mass in the 5-15 Earth-mass range
despite the fact that the method is more than 20  times more sensitive
to planets of a Jupiter-mass.  This implies that about one third of
all stars have such "super-Earth" planets of ~10  Earth-masses at
orbital separations where microlensing is most sensitive:  1-5 AU.
This also indicates that cool, super-Earths are probably the most
common type of extrasolar planet yet to be discovered.  

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