A low Earth Orbit Satellite Could Detect Earth Mass Free Floating Exoplanets

Microlensing planet detection via geosynchronous and low Earth orbit satellites

Authors:

Mogavero et al

Abstract:

Planet detection through microlensing is usually limited by a well-known degeneracy in the Einstein timescale tE, which prevents mass and distance of the lens to be univocally determined. Gould (2013) has shown that a satellite in geosynchronous orbit could provide masses and distances for most standard planetary events (tE≈20 days) via a microlens parallax measurement. This paper extends the analysis to shorter Einstein timescales, tE≈1 day, dealing with the case of Jupiter-mass lenses. We then study the capabilities of a low Earth orbit satellite at even shorter timescales, tE≈0.1 days. A Fisher matrix analysis is employed to predict how the 1-sigma error on parallax depends on tE and the peak magnification of the microlensing event. It is shown that a geosynchronous satellite could detect parallaxes for Jupiter-mass free-floaters and discover planetary systems around very low-mass brown dwarfs. Moreover, a low Earth orbit satellite could lead to the discovery of Earth-mass free-floating planets. Limitations to these results can be the strong requirements on the photometry, the effects of blending and, in case of the low orbit, the Earth umbra.