Spitzer as Microlens Parallax Satellite: Mass Measurement for the OGLE-2014-BLG-0124L Planet and its Host Star

Abstract

We combine Spitzer and ground-based observations to measure the microlens parallax vector ${\pi }_{\mathrm{E}}$, and so the mass and distance of OGLE-2014-BLG-0124L, making it the first microlensing planetary system with a space-based parallax measurement. The planet and star have masses $m\sim 0.5M_{\mathrm{jup}}$ and $M\sim 0.7M_{\odot }$ and are separated by $a_{\perp }\sim 3.1$ AU in projection. The main source of uncertainty in all these numbers (approximately 30%, 30%, and 20%) is the relatively poor measurement of the Einstein radius ${\theta }_{\mathrm{E}}$, rather than uncertainty in ${\pi }_{\mathrm{E}}$, which is measured with 2.5% precision. This compares to 22% based on OGLE data alone, implying that the Spitzer data provide not only a substantial improvement in the precision of the ${\pi }_{\mathrm{E}}$ measurement but also the first independent test of a ground-based ${\pi }_{\mathrm{E}}$ measurement.

submitted to ApJ, 30 pages, 6 figures, 4 tables

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• OGLE-2014-BLG-1112LB: A Microlensing Brown Dwarf Detected Through the Channel of a Gravitational Binary-Lens Event
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