Spitzer as Microlens Parallax Satellite: Mass and Distance Measurements of Binary Lens System OGLE-2014-BLG-1050L

TL;DR

This paper demonstrates the use of the Spitzer space telescope to measure the mass and distance of a binary lens system through microlens parallax, revealing the potential of this method for studying stellar binaries.

Contribution

First mass and distance measurement of a caustic-crossing binary system using space-based microlens parallax, highlighting the method's effectiveness.

Findings

Detected a four-fold degeneracy in the binary lens solution.

Preferred solution indicates a higher-mass binary at ~3.5 kpc.

Showcased microlens parallax's power in binary system analysis.

Abstract

We report the first mass and distance measurement of a caustic-crossing binary system OGLE-2014-BLG-1050L using the space-based microlens parallax method. \emph{Spitzer} captured the second caustic-crossing of the event, which occurred $\sim$10 days before that seen from Earth. Due to the coincidence that the source-lens relative motion was almost parallel to the direction of the binary-lens axis, the four-fold degeneracy, which was known before only to occur in single-lens events, persists in this case, leading to either a lower-mass (0.2 $M_\odot$ and 0.07 $M_\odot$) binary at $\sim$1.1 kpc or a higher-mass (0.9 $M_\odot$ and 0.35 $M_\odot$) binary at $\sim$3.5 kpc. However, the latter solution is strongly preferred for reasons including blending and lensing probability. OGLE-2014-BLG-1050L demonstrates the power of microlens parallax in probing stellar and substellar binaries.