A New Non-Planetary Interpretation of the Microlensing Event OGLE-2013-BLG-0723

TL;DR

This paper reanalyzes the microlensing event OGLE-2013-BLG-0723, proposing a non-planetary two-star lens model that better fits the observed data than the previous planetary interpretation.

Contribution

It introduces a new two-body lens model for the event, challenging the prior planetary hypothesis and emphasizing the importance of exploring alternative lens configurations.

Findings

The new model has a better fit with Δχ²≈202.

The lens system likely consists of two low-mass stars (~0.2 and 0.1 solar masses).

The system is approximately 3 kpc away, consistent with common lens populations.

Abstract

Recently, the discovery of a Venus-mass planet orbiting a brown-dwarf host in a binary system was reported from the analysis of the microlensing event OGLE-2013-BLG-0723. We reanalyze the event considering the possibility of other interpretations. From this, we find a new solution where the lens is composed of 2 bodies in contrast to the 3-body solution of the previous analysis. The new solution better explains the observed light curve than the previous solution with $\Delta\chi^2\sim 202$, suggesting that the new solution is a correct model for the event. From the estimation of the physical parameters based on the new interpretation, we find that the lens system is composed of two low-mass stars with $\sim 0.2\ M_\odot$ and $\sim 0.1\ M_\odot$ and located at a distance $\sim 3$ kpc. The fact that the physical parameters correspond to those of the most common lens population located at a distance with a large lensing probability further supports the likelihood of the new interpretation. Considering that two dramatically different solutions can approximately explain the observed light curve, the event suggests the need of carefully testing all possible lens-system geometries.