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Article

Accurate Mass Measurements for Planetary Microlensing Events Using High Angular Resolution Observations

1
School of Physical Sciences, University of Tasmania, Private Bag 37 Hobart, Tasmania 7001, Australia
2
Sorbonne Universités, UPMC Université Paris 6 et CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
Universe 2018, 4(4), 61; https://doi.org/10.3390/universe4040061
Received: 5 March 2018 / Revised: 5 April 2018 / Accepted: 8 April 2018 / Published: 24 April 2018
(This article belongs to the Special Issue Gravitational Lensing and Astrometry)
The microlensing technique is a unique method to hunt for cold planets over a range of mass and separation, orbiting all varieties of host stars in the disk of our galaxy. It provides precise mass-ratio and projected separations in units of the Einstein ring radius. In order to obtain the physical parameters (mass, distance, orbital separation) of the system, it is necessary to combine the result of light curve modeling with lens mass-distance relations and/or perform a Bayesian analysis with a galactic model. A first mass-distance relation could be obtained from a constraint on the Einstein ring radius if the crossing time of the source over the caustic is measured. It could then be supplemented by secondary constraints such as parallax measurements, ideally by using coinciding ground and space-born observations. These are still subject to degeneracies, like the orbital motion of the lens. A third mass-distance relation can be obtained thanks to constraints on the lens luminosity using high angular resolution observations with 8 m class telescopes or the Hubble Space Telescope. The latter route, although quite inexpensive in telescope time is very effective. If we have to rely heavily on Bayesian analysis and limited constraints on mass-distance relations, the physical parameters are determined to 30–40% typically. In a handful of cases, ground-space parallax is a powerful route to get stronger constraint on masses. High angular resolution observations will be able to constrain the luminosity of the lenses in the majority of the cases, and in favorable circumstances it is possible to derive physical parameters to 10% or better. Moreover, these constraints will be obtained in most of the planets to be discovered by the Euclid and WFIRST satellites. We describe here the state-of-the-art approaches to measure lens masses and distances with an emphasis on high angular resolution observations. We will discuss the challenges, recent results and perspectives. View Full-Text
Keywords: exoplanets; planetary systems; microlensing; adaptive optics exoplanets; planetary systems; microlensing; adaptive optics
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MDPI and ACS Style

Beaulieu, J.-P. Accurate Mass Measurements for Planetary Microlensing Events Using High Angular Resolution Observations. Universe 2018, 4, 61. https://doi.org/10.3390/universe4040061

AMA Style

Beaulieu J-P. Accurate Mass Measurements for Planetary Microlensing Events Using High Angular Resolution Observations. Universe. 2018; 4(4):61. https://doi.org/10.3390/universe4040061

Chicago/Turabian Style

Beaulieu, Jean-Philippe. 2018. "Accurate Mass Measurements for Planetary Microlensing Events Using High Angular Resolution Observations" Universe 4, no. 4: 61. https://doi.org/10.3390/universe4040061

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