Planetary microlensing at high magnification

• Published in: Monthly notices of the Royal Astronomical Society Vol. 335; no. 1; pp. 159 - 169
• Main Authors: Rattenbury, N. J., Bond, I. A., Skuljan, J., Yock, P. C. M.
• Format: Journal Article
• Language: English
• Published: 23 Ainslie Place , Edinburgh EH3 6AJ , UK . Telephone 226 7232 Fax 226 3803 Blackwell Science Ltd 01.09.2002
• Subjects: gravitational lensing; methods: numerical; planetary systems; methods: numerical; gravitational lensing; planetary systems
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1046/j.1365-8711.2002.05607.x

Simulations of planetary microlensing at high magnification that were carried out on a cluster computer are presented. It was found that the perturbations owing to two-thirds of all planets occur in the time interval −0.5tFWHM,0.5tFWHM with respect to the peak of the microlensing light curve, where tFWHM is typically ∼14 h. This implies that only this restricted portion of the light curve need be intensively monitored for planets – a very significant practical advantage. Nearly all planetary detections in high-magnification events will not involve caustic crossings. We discuss the issues involved in determining the planetary parameters in high magnification events. Earth-mass planets may be detected with 1-m class telescopes if their projected orbital radii lie within about 1.5–2.5 au. Giant planets are detectable over a much larger region. For multiplanet systems the perturbations caused by individual planets can be separated under certain conditions. The size of the source star needs to be determined independently, but the presence of spots on the source star is likely to be negligible, as is the effect of planetary motion during an event.