Gravitational Microlensing Evidence for a Planet Orbiting a Binary Star System

TL;DR

This paper reports the first discovery of a planet orbiting a binary star system using gravitational microlensing, revealing that giant planets can be common in such systems and expanding our understanding of planetary formation.

Contribution

It provides the first evidence of a planet orbiting a binary star system through microlensing, demonstrating a new method for detecting exoplanets in complex systems.

Findings

Discovery of a planet orbiting a binary star system.

First detection of a Jovian planet via microlensing.

Binary stars likely host giant planets more frequently.

Abstract

The study of extra-solar planetary systems has emerged as a new discipline of observational astronomy in the past few years with the discovery of a number of extra-solar planets. The properties of most of these extra-solar planets were not anticipated by theoretical work on the formation of planetary systems. Here we report observations and light curve modeling of gravitational microlensing event MACHO-97-BLG-41, which indicates that the lens system consists of a planet orbiting a binary star system. According to this model, the mass ratio of the binary star system is 3.8:1 and the stars are most likely to be a late K dwarf and an M dwarf with a separation of about 1.8 AU. A planet of about 3 Jupiter masses orbits this system at a distance of about 7 AU. If our interpretation of this light curve is correct, it represents the first discovery of a planet orbiting a binary star system and the first detection of a Jovian planet via the gravitational microlensing technique. It suggests that giant planets may be common in short period binary star systems.