ORCID Profile
0000-0002-4355-9838
Current Organisation
Harvard-Smithsonian Center for Astrophysics
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Publisher: American Astronomical Society
Date: 23-11-2015
Publisher: American Astronomical Society
Date: 03-11-2017
Publisher: American Astronomical Society
Date: 28-12-2017
Publisher: American Astronomical Society
Date: 18-08-2023
Abstract: We present an analysis of microlensing event OGLE-2019-BLG-0825. This event was identified as a planetary candidate by preliminary modeling. We find that significant residuals from the best-fit static binary-lens model exist and a xallarap effect can fit the residuals very well and significantly improves χ 2 values. On the other hand, by including the xallarap effect in our models, we find that binary-lens parameters such as mass ratio, q , and separation, s , cannot be constrained well. However, we also find that the parameters for the source system such as the orbital period and semimajor axis are consistent between all the models we analyzed. We therefore constrain the properties of the source system better than the properties of the lens system. The source system comprises a G-type main-sequence star orbited by a brown dwarf with a period of P ∼ 5 days. This analysis is the first to demonstrate that the xallarap effect does affect binary-lens parameters in planetary events. It would not be common for the presence or absence of the xallarap effect to affect lens parameters in events with long orbital periods of the source system or events with transits to caustics, but in other cases, such as this event, the xallarap effect can affect binary-lens parameters.
Publisher: Oxford University Press (OUP)
Date: 10-07-2019
Abstract: We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 Spitzer microlensing c aign. 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.
Publisher: American Astronomical Society
Date: 05-05-2014
Publisher: American Astronomical Society
Date: 11-08-2015
Publisher: American Astronomical Society
Date: 27-02-2017
Publisher: American Astronomical Society
Date: 08-01-2015
Publisher: American Astronomical Society
Date: 08-2012
Publisher: American Astronomical Society
Date: 02-03-2016
Publisher: American Astronomical Society
Date: 22-03-2016
Publisher: American Astronomical Society
Date: 23-04-2013
Publisher: American Astronomical Society
Date: 28-06-2016
Publisher: American Astronomical Society
Date: 07-04-2014
Publisher: American Astronomical Society
Date: 14-11-2012
Publisher: American Astronomical Society
Date: 16-10-2015
Publisher: American Astronomical Society
Date: 11-2013
Publisher: EDP Sciences
Date: 27-03-2013
Publisher: American Astronomical Society
Date: 13-08-2012
Publisher: American Astronomical Society
Date: 27-11-2013
Publisher: American Astronomical Society
Date: 19-12-2012
Publisher: American Association for the Advancement of Science (AAAS)
Date: 04-07-2014
Abstract: Many known exoplanets (planets outside our own solar system) are hosted by binary systems that contain two stars. These planets normally circle around both of their stars. Using microlensing data taken with a worldwide network of telescopes, Gould et al. found a planet twice the mass of Earth that circles just one of a pair of stars. The same approach has the potential to uncover other similar star systems and help to illuminate some of the mysteries of planet formation. Science , this issue p. 46
Publisher: American Astronomical Society
Date: 24-09-2014
Publisher: American Astronomical Society
Date: 27-06-2202
Publisher: American Astronomical Society
Date: 02-2012
Publisher: American Astronomical Society
Date: 02-08-2022
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 θ E cannot be measured from the light curve alone. However, the large event duration, t E ∼ 80 days, allows a precise measurement of the microlensing parallax π E . In addition to the constraints on the angular radius θ * and the apparent brightness I s of the source, we employ the Besançon 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 M p ∼ 30 M Jup , 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 ≤4 kpc. We estimate that in about 10 yr 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.
Publisher: American Astronomical Society
Date: 11-02-2019
Publisher: American Astronomical Society
Date: 18-08-2017
Publisher: American Astronomical Society
Date: 12-11-2013
Publisher: American Astronomical Society
Date: 28-01-2013
Publisher: American Astronomical Society
Date: 07-09-2030
Publisher: American Astronomical Society
Date: 02-05-2012
Publisher: American Astronomical Society
Date: 20-06-2011
Publisher: American Astronomical Society
Date: 28-04-2015
Publisher: American Astronomical Society
Date: 06-07-2012
Publisher: American Astronomical Society
Date: 10-05-0010
Abstract: OGLE-2016-BLG-1093 is a planetary microlensing event that is part of the statistical Spitzer microlens parallax s le. The precise measurement of the microlens parallax effect for this event, combined with the measurement of finite-source effects, leads to a direct measurement of the lens masses and system distance, M host =0.38–0.57 M ⊙ and m p = 0.59–0.87 M Jup , and the system is located at the Galactic bulge ( D L ∼ 8.1 kpc). Because this was a high-magnification event, we are also able to empirically show that the “cheap-space parallax” concept produces well-constrained (and consistent) results for ∣ π E ∣. This demonstrates that this concept can be extended to many two-body lenses. Finally, we briefly explore systematics in the Spitzer light curve in this event and show that their potential impact is strongly mitigated by the color constraint.
Publisher: American Astronomical Society
Date: 05-04-2017
Publisher: American Astronomical Society
Date: 23-07-2020
Publisher: American Astronomical Society
Date: 31-07-2012
Publisher: American Astronomical Society
Date: 27-04-2015
Publisher: Oxford University Press (OUP)
Date: 02-07-2012
Publisher: American Astronomical Society
Date: 03-07-2017
Publisher: American Astronomical Society
Date: 08-01-2013
Publisher: American Astronomical Society
Date: 24-03-2023
Abstract: We analyze the MOA-2020-BLG-208 gravitational microlensing event and present the discovery and characterization of a new planet, MOA-2020-BLG-208Lb, with an estimated sub-Saturn mass. With a mass ratio q = 3.17 − 0.26 + 0.28 × 10 − 4 , the planet lies near the peak of the mass-ratio function derived by the MOA collaboration and near the edge of expected s le sensitivity. For these estimates we provide results using two mass-law priors: one assuming that all stars have an equal planet-hosting probability, and the other assuming that planets are more likely to orbit around more massive stars. In the first scenario, we estimate that the lens system is likely to be a planet of mass m planet = 46 − 24 + 42 M ⊕ and a host star of mass M host = 0.43 − 0.23 + 0.39 M ⊙ , located at a distance D L = 7.49 − 1.13 + 0.99 kpc . For the second scenario, we estimate m planet = 69 − 34 + 37 M ⊕ , M host = 0.66 − 0.32 + 0.35 M ⊙ , and D L = 7.81 − 0.93 + 0.93 kpc . The planet has a projected separation as a fraction of the Einstein ring radius s = 1.3807 − 0.0018 + 0.0018 . As a cool sub-Saturn-mass planet, this planet adds to a growing collection of evidence for revised planetary formation models.
Publisher: American Astronomical Society
Date: 07-07-2016
Publisher: American Astronomical Society
Date: 27-01-2014
Location: United States of America
Location: Korea, Republic of
No related grants have been discovered for In-Gu Shin.