# The Lowest Mass Ratio Planetary Microlens: OGLE 2016-BLG-1195Lb

## TL;DR

This paper reports the discovery of the lowest mass ratio exoplanet detected via microlensing, revealing a small deviation in the light curve indicative of a cold, Earth-mass planet orbiting a low-mass star at 7.1 kpc.

## Contribution

It presents the first detection of an exoplanet with an extremely low mass ratio using microlensing, demonstrating the method's sensitivity to Earth-mass planets.

## Key findings

- Mass ratio of the planet is approximately 4.2 x 10^{-5}.
- The planet is estimated to be about 3 Earth masses.
- The host star is likely a 0.2 Solar mass star at 7.1 kpc.

## Abstract

We report discovery of the lowest mass ratio exoplanet to be found by the microlensing method in the light curve of the event OGLE~2016--BLG--1195. This planet revealed itself as a small deviation from a microlensing single lens profile from an examination of the survey data soon after the planetary signal. The duration of the planetary signal is $\sim 2.5\,$hours. The measured ratio of the planet mass to its host star is $q = 4.2\pm 0.7 \times10^{-5}$. We further estimate that the lens system is likely to comprise a cold $\sim$3 Earth mass planet in a $\sim\,$2 AU wide orbit around a 0.2 Solar mass star at an overall distance of 7.1 kpc.