MOA-2019-BLG-008Lb: a new microlensing detection of an object at the planet/brown dwarf boundary

Abstract

We report on the observations, analysis and interpretation of the microlensing event MOA-2019- BLG-008. The observed anomaly in the photometric light curve is best described through a binary lens model. In this model, the source did not cross caustics and no finite source effects were observed. Therefore the angular Einstein ring radius cannot be measured from the light curve alone. However, the large event duration, t E about 80 days, allows a precise measurement of the microlensing parallax. In addition to the constraints on the angular radius and the apparent brightness I s of the source, we employ the Besancon and GalMod galactic models to estimate the physical properties of the lens. We find excellent agreement between the predictions of the two Galactic models: the companion is likely a resident of the brown dwarf desert with a mass Mp about 30 MJup and the host is a main sequence dwarf star. The lens lies along the line of sight to the Galactic Bulge, at a distance of less then4 kpc. We estimate that in about 10 years, the lens and source will be separated by 55 mas, and it will be possible to confirm the exact nature of the lensing system by using high-resolution imaging from ground or space-based observatories.

Accepted in AJ

References in corpus (31)

• The Gaia mission
• Wide-Field InfrarRed Survey Telescope-Astrophysics Focused Telescope Assets WFIRST-AFTA 2015 Report
• One or more bound planets per Milky Way star from microlensing observations
• The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
• Microlens OGLE-2005-BLG-169 Implies Cool Neptune-Like Planets are Common
• The Gemini Deep Planet Survey -- GDPS
• The Palomar/Keck Adaptive Optics Survey of Young Solar Analogs: Evidence for a Universal Companion Mass Function
• Mapping the Shores of the Brown Dwarf Desert I.: Upper Scorpius
• A New Algorithm For Difference Image Analysis
• Population-Level Eccentricity Distributions of Imaged Exoplanets and Brown Dwarf Companions: Dynamical Evidence for Distinct Formation Channels
• MOA-cam3: a wide-field mosaic CCD camera for a gravitational microlensing survey in New Zealand
• Constraining the thick disc formation scenario of the Milky Way
• OGLE-IV: Fourth Phase of the Optical Gravitational Lensing Experiment
• Pathway to the Galactic Distribution of Planets: Combined Spitzer and Ground-Based Microlens Parallax Measurements of 21 Single-Lens Events
• Predictions of the Nancy Grace Roman Space Telescope Galactic Exoplanet Survey II: Free-Floating Planet Detection Rates
• CHARA Array Measurements of the Angular Diameters of Exoplanet Host Stars
• Exploring the Local Milky Way: M Dwarfs as Tracers of Galactic Populations
• Empirical photometric calibration of the Gaia Red Clump: colours, effective temperature and absolute magnitude
• First Space-based Microlens Parallax Measurement of an Isolated Star: Spitzer Observations of OGLE-2014-BLG-0939
• Kinematics of the local disk from the RAVE survey and the Gaia first data release
• Predicting Stellar Angular Diameters from $V$, $I_C$, $H$, $K$ Photometry
• A Parametric Galactic Model toward the Galactic Bulge Based on Gaia and Microlensing Data
• The VMC survey -- XXXVIII. Proper motion of the Magellanic Bridge
• Simulating JWST deep extragalactic imaging surveys and physical parameter recovery
• MaB$\mu$lS-2: high-precision microlensing modelling for the large-scale survey era
• ROME/REA: A gravitational microlensing search for exo-planets beyond the snow-line on a global network of robotic telescopes
• OGLE-2018-BLG-0022: A Nearby M-dwarf Binary
• OGLE-2013-BLG-0911Lb: A Secondary on the Brown-Dwarf Planet Boundary around an M-dwarf
• Comparing Observed Stellar Kinematics and Surface Densities in a Low Latitude Bulge Field to Galactic Population Synthesis Models
• The California Legacy Survey II. Occurrence of Giant Planets Beyond the Ice line
• Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes

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