Korea Microlensing Telescope Network Microlensing Events from 2015: Event-finding Algorithm, Vetting, and Photometry

Kim, D. J.; Kim, H. W.; Hwang, Kyu-Ha; Albrow, M. D.; Chung, Sun-Ju; Gould, Andrew; Han, Cheongho; Jung, Youn Kil; Ryu, Yoon-Hyun; Shin, In-Gu; Yee, Jennifer C.; Zhu, Wei; M., S.; Kim, S. L.; Lee, C. U.; Lee, D. J.; Lee, Y.; Park, B. G.; Pogge, Richard W.

doi:10.3847/1538-3881/aaa47b

Cited by 113 publications

(93 citation statements)

References 36 publications

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“…For this event, the cadence of the MOA observations is about Γ = 3 hr −1 . The Korea Microlensing Telescope Network (KMTNet) group also observed this event, which it independently discovered as KMT-2017-BLG-0357 (Kim et al 2018), using its three 1.6 m telescopes equipped with 4 deg 2 FOV cameras at the Cerro Tololo International Observatory (CTIO) in Chile (KMTC), the South African Astronomical Observatory (SAAO) in South Africa (KMTS), and the Siding Spring Observatory (SSO) in Australia (KMTA) (Kim et al 2016) with a cadence of Γ = 4 hr −1 . The vast majority of OGLE and KMTNet observations were carried out in the I-band, while MOA images were taken in a customized MOA-Red filter, which is similar to the sum of the standard Cousins R-and I-band filters.…”

Section: Observationsmentioning

confidence: 95%

OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing

Li¹,

Zang²,

Udalski³

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Abstract We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 Spitzer microlensing campaign. This is a remarkable microlensing event because its source is photometrically bright and variable, which makes it possible to perform an asteroseismic analysis using ground-based data. We find that the source star is an oscillating red giant with average time-scale of ∼9 d. The asteroseismic analysis also provides us source properties including the source angular size (∼27 $\mu$as) and distance (∼11.5 kpc), which are essential for inferring the properties of the lens. When fitting the light curve, we test the feasibility of Gaussian processes (GPs) in handling the correlated noise caused by the variable source. We find that the parameters from the GP model are generally more loosely constrained than those from the traditional χ2 minimization method. We note that this event is the first microlensing system for which asteroseismology and GPs have been used to account for the variable source. With both finite-source effect and microlens parallax measured, we find that the lens is likely a ∼0.045 M⊙ brown dwarf at distance ∼9.0 kpc, or a ∼0.073 M⊙ ultracool dwarf at distance ∼9.8 kpc. Combining the estimated lens properties with a Bayesian analysis using a Galactic model, we find a $\sim 35{{\ \rm per\ cent}}$ probability for the lens to be a bulge object and $\sim 65{{\ \rm per\ cent}}$ to be a background disc object.

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Section: Observationsmentioning

confidence: 95%

OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing

Li¹,

Zang²,

Udalski³

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…We searched the full 2017 dataset for microlensing events using the new event detection algorithm of Kim et al (2018). Among the events found (the full analysis will be presented in a subsequent paper), we identified UKIRT-2017-BLG-001.…”

Section: Observationsmentioning

confidence: 99%

UKIRT-2017-BLG-001Lb: A Giant Planet Detected through the Dust

Shvartzvald

Novati

Gaudi

et al. 2018

ApJL

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We report the discovery of a giant planet in event UKIRT-2017-BLG-001, detected by the UKIRT microlensing survey. The mass ratio between the planet and its host is q = 1.50 +0.17 −0.14 × 10 −3 , about 1.5 times the Jupiter/Sun mass ratio. The event lies 0.35 • from the Galactic center and suffers from high extinction of A K = 1.68. Therefore, it could be detected only by a near-infrared survey. The field also suffers from large spatial differential extinction, which makes it difficult to estimate the source properties required to derive the angular Einstein radius. Nevertheless, we find evidence suggesting that the source is located in the far disk. If correct, this would be the first source star of a microlensing event to be identified as belonging to the far disk. We estimate the lens mass and distance using a Bayesian analysis to find that the planet's mass is 1.28 +0.37 −0.44 M J , and it orbits a 0.81 +0.21 −0.27 M star at an instantaneous projected separation of 4.18 +0.96 −0.88 AU. The system is at a distance of 6.3 +1.6 −2.1 kpc, and so likely resides in the Galactic bulge. In addition, we find a non-standard extinction curve in this field, in agreement with previous results toward high-extinction fields near the Galactic center. Subject headings: gravitational lensing: micro -Galaxy: bulge-binaries: general -planetary systems 8 Based on the extinctions of red clump stars measured by Nidever et al. (2012), the current WFIRST fields have quartile K s extinctions of 0.38 and 0.64.

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“…Beginning in 2016, KMTNet monitors a total of (3, 7, 11, 2) fields at cadences of Γ ∼ (4, 1, 0.4, 0.2) hr −1 . See Figure 12 of Kim et al (2018a). This new strategy mainly aims to support Spitzer microlensing campaign (Gould et al 2013(Gould et al , 2014(Gould et al , 2015a(Gould et al ,b, 2016(Gould et al , 2018 and find more planets over a much broader area.…”

Section: Introductionmentioning

confidence: 99%

KMT-2016-BLG-1836Lb: A Super-Jovian Planet from a High-cadence Microlensing Field

Yang

Zhang²,

Hwang

et al. 2020

Self Cite

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We report the discovery of a super-Jovian planet in the microlensing event KMT-2016-BLG-1836, which was found by the Korea Microlensing Telescope Network's high-cadence observations (Γ ∼ 4 hr −1 ). The planet-host mass ratio q ∼ 0.004. A Bayesian analysis indicates that the planetary system is composed of a super-Jovian M planet = 2.2 +1.9 −1.1 M J planet orbiting an M or K dwarf M host = 0.49 +0.38 −0.25 M , at a distance of D L = 7.1 +0.8 −2.4 kpc. The projected planet-host separation is 3.5 +1.1 −0.9 AU, implying that the planet is located beyond the snowline of the host star. Future high-resolution images can potentially strongly constrain the lens brightness and thus the mass and distance of the planetary system. Without considering detailed detection efficiency, selection or publication biases, we find a potential "mass ratio desert" at −3.7 log q −3.0 for the 29 published KMTNet planets.

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Korea Microlensing Telescope Network Microlensing Events from 2015: Event-finding Algorithm, Vetting, and Photometry

Cited by 113 publications

References 36 publications

OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing

OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing

UKIRT-2017-BLG-001Lb: A Giant Planet Detected through the Dust

KMT-2016-BLG-1836Lb: A Super-Jovian Planet from a High-cadence Microlensing Field

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