4 research outputs found
Simulations of Triple Microlensing Events I: Detectability of a scaled Sun-Jupiter-Saturn System
Up to date, only 13 firmly established triple microlensing events have been
discovered, so the occurrence rates of microlensing two-planet systems and
planets in binary systems are still uncertain. With the upcoming space-based
microlensing surveys, hundreds of triple microlensing events will be detected.
To provide clues for future observations and statistical analyses, we initiate
a project to investigate the detectability of triple-lens systems with
different configurations and observational setups. As the first step, in this
work we develop the simulation software and investigate the detectability of a
scaled Sun-Jupiter-Saturn system with the recently proposed microlensing
telescope of the ``Earth 2.0 (ET)'' mission. We find that the detectability of
the scaled Sun-Jupiter-Saturn analog is about 1%. In addition, the presence of
the Jovian planet suppresses the detectability of the Saturn-like planet by
13% regardless of the adopted detection threshold. This
suppression probability could be at the same level as the Poisson noise of
future space-based statistical samples of triple-lenses, so it is inappropriate
to treat each planet separately during detection efficiency calculations.Comment: 14 pages, 11 figures, submitted to MNRAS, comments welcome
OGLE-2019-BLG-1470LABc : another microlensing giant planet in a binary system?
We report the discovery and analysis of a candidate triple-lens single-source (3L1S) microlensing event, OGLE-2019-BLG-1470. This event was first classified as a normal binary-lens single-source (2L1S) event, but a careful 2L1S modelling showed that it needs an additional lens or source to fit the observed data. It is found that the 3L1S model provides the best fit, but the binary-lens binary-source (2L2S) model is only disfavoured by Δχ2 ≃ 18. All of the feasible models include a planet with planet-to-host mass-ratios 10−3 ≲ q ≲ 10−2. A Bayesian analysis based on a Galactic model indicates that the planet is super-Jovian, and the projected host-planet separation is about 3 au. Specifically, for the best-fitting 3L1S model, the two stars have masses of M1=0.57+0.43−0.32M⊙, and M2=0.18+0.15−0.10M⊙ with projected separation of 1.3+0.5−0.5 au, and the planetary mass is M3=2.2+1.8−1.3MJupiter. For the 2L2S model, the masses of the host star and the planet are 0.55+0.44−0.31M⊙ and 4.6+3.7−2.6MJupiter, respectively. By investigating the properties of all known microlensing planets in binary systems, we find that all planets in binary systems published by the KMTNet survey are located inside the resonant caustics range with q ≳ 2 × 10−3, indicating the incompleteness of the KMTNet sample for planets in binary systems. Thus, planets in binary systems cannot be included in the current study of the KMTNet mass-ratio function, and a systematic search for planetary anomalies in KMTNet microlensing light curves of binary systems is needed
ET White Paper: To Find the First Earth 2.0
We propose to develop a wide-field and ultra-high-precision photometric
survey mission, temporarily named "Earth 2.0 (ET)". This mission is designed to
measure, for the first time, the occurrence rate and the orbital distributions
of Earth-sized planets. ET consists of seven 30cm telescopes, to be launched to
the Earth-Sun's L2 point. Six of these are transit telescopes with a field of
view of 500 square degrees. Staring in the direction that encompasses the
original Kepler field for four continuous years, this monitoring will return
tens of thousands of transiting planets, including the elusive Earth twins
orbiting solar-type stars. The seventh telescope is a 30cm microlensing
telescope that will monitor an area of 4 square degrees toward the galactic
bulge. This, combined with simultaneous ground-based KMTNet observations, will
measure masses for hundreds of long-period and free-floating planets. Together,
the transit and the microlensing telescopes will revolutionize our
understandings of terrestrial planets across a large swath of orbital distances
and free space. In addition, the survey data will also facilitate studies in
the fields of asteroseismology, Galactic archeology, time-domain sciences, and
black holes in binaries.Comment: 116 pages,79 figure