%0 Journal Article
%T Study by MOA of extra-solar planets in gravitational microlensing events of high magnification
%A I. A. Bond
%A N. J. Rattenbury
%A J. Skuljan
%A F. Abe
%A R. J. Dodd
%A J. B. Hearnshaw
%A M. Honda
%A J. Jugaku
%A P. M. Kilmartin
%A A. Marles
%A K. Masuda
%A Y. Matsubara
%A Y. Muraki
%A T. Nakamura
%A G. Nankivell
%A S. Noda
%A C. Noguchi
%A K. Ohnishi
%A M. Reid
%A To. Saito
%A H. Sato
%A M. Sekiguchi
%A D. J. Sullivan
%A T. Sumi
%A M. Takeuti
%A Y. Watase
%A S. Wilkinson
%A R. Yamada
%A T. Yanagisawa
%A P. C. M. Yock
%J Physics
%D 2001
%I arXiv
%R 10.1046/j.1365-8711.2002.05380.x
%X A search for extra-solar planets was carried out in three gravitational microlensing events of high magnification, MACHO 98-BLG-35, MACHO 99-LMC-2, and OGLE 00-BUL-12. Photometry was derived from observational images by the MOA and OGLE groups using an image subtraction technique. For MACHO 98-BLG-35, additional photometry derived from the MPS and PLANET groups was included. Planetary modeling of the three events was carried out in a super-cluster computing environment. The estimated probability for explaining the data on MACHO 98-BLG-35 without a planet is <1%. The best planetary model has a planet of mass ~(0.4-1.5) X 10^-5 M_Earth at a projected radius of either ~1.5 or ~2.3 AU. We show how multi-planet models can be applied to the data. We calculated exclusion regions for the three events and found that Jupiter-mass planets can be excluded with projected radii from as wide as about 30 AU to as close as around 0.5 AU for MACHO 98-BLG-35 and OGLE 00-BUL-12. For MACHO 99-LMC-2, the exclusion region extends out to around 10 AU and constitutes the first limit placed on a planetary companion to an extragalactic star. We derive a particularly high peak magnification of ~160 for OGLE 00-BUL-12. We discuss the detectability of planets with masses as low as Mercury in this and similar events.
%U http://arxiv.org/abs/astro-ph/0102184v2