KMT-2019-BLG-1715: Planetary Microlensing Event with Three Lens Masses and Two Source Stars (original) (raw)
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Full characterization of binary-lens event OGLE-2002-BLG-069 from PLANET observations
2005
We analyze the photometric data obtained by PLANET and OGLE on the caustic-crossing binary-lens microlensing event OGLE-2002-BLG-069. Thanks to the excellent photometric and spectroscopic coverage of the event, we are able to constrain the lens model up to the known ambiguity between close and wide binary lenses. The detection of annual parallax in combination with measurements of extended-source effects allows us to determine the mass, distance and velocity of the lens components for the competing models. While the model involving a close binary lens leads to a Bulge-Disc lens scenario with a lens mass of M = (0.51 ± 0.15) M⊙ and distance of DL = (2.9 ± 0.4) kpc, the wide binary lens solution requires a rather implausible binary black-hole lens (M 126 M⊙). Furthermore we compare current state-of-the-art numerical and empirical models for the surface brightness profile of the source, a G5III Bulge giant. We find that a linear limb-darkening model for the atmosphere of the source star is consistent with the data whereas a PHOENIX atmosphere model assuming LTE and with no free parameter does not match our observations.
OGLE-2019-BLG-0468Lb,c: Two microlensing giant planets around a G-type star
Astronomy & Astrophysics, 2021
Aims. With the aim of interpreting anomalous lensing events with no suggested models, we conducted a project of reinvestigating microlensing data collected in and before the 2019 season. In this work, we report a multi-planet system, OGLE-2019-BLG-0468L, that was found as a result of this project. Methods. The light curve of the lensing event OGLE-2019-BLG-0468, which consists of three distinctive anomaly features, could not be explained by the usual binary-lens or binary-source interpretations. We find a solution that explains all anomaly features with a triple-lens interpretation, in which the lens is composed of two planets and their host, making the lens the fourth multi-planet system securely found by microlensing. Results. The two planets have masses of ~3.4 MJ and ~10.2 MJ, and they are orbiting around a G-type star with a mass of ~0.9 M⊙ and a distance of ~4.4 kpc. The host of the planets is most likely responsible for the light of the baseline object, although the possibili...
Ambiguities in fits of binary lens galactic microlensing events
1997
For observed galactic microlensing events only one fit is usually presented, though, especially for a binary lens, several fits may be possible. This has been shown for the MACHO LMC#1 event (Dominik & Hirshfeld 1996). Here I discuss the strong binary lens events OGLE#7 and DUO#2. It is shown that several models with a large variety of parameters are in accordance with the photometric data. For most of the fits, 1-sigma-bounds on the fit parameters are given. The variation of the parameters within the bounds is in some cases considerable. It is likely that other binary lens systems which will occur will have properties similar to the discussed events.
A binary lensing event toward the LMC: Observations and dark matter implications
Nuclear Physics B - Proceedings Supplements, 1996
The MACHO collaboration has recently analyzed 2.1 years of photometric data for about 8.5 million stars in the Large Magellanic Cloud (LMC). This analysis has revealed 8 candidate microlensing events and a total microlensing optical depth of τmeas = 2.9 +1.4 −0.9 × 10 −7 . This significantly exceeds the number of events (1.1) and the microlensing optical depth predicted from known stellar populations: τ back = 5.4 × 10 −8 , but it is consistent with models in which about half of the standard dark halo mass is composed of Machos of mass ∼ 0.5M⊙. One of these 8 events appears to be a binary lensing event with a caustic crossing that is partially resolved, and the measured caustic crossing time allows us to estimate the distance to the lenses. Under the assumption that the source star is a single star and not a short period binary, we show that the lensing objects are very likely to reside in the LMC. However, if we assume that the optical depth for LMC-LMC lensing is large enough to account for our entire lensing signal, then the binary event does not appear to be consistent with lensing of a single LMC source star by a binary residing in the LMC. Thus, while the binary lens may indeed reside in the LMC, there is no indication that most of the lenses reside in the LMC.
The First Planetary Microlensing Event with Two Microlensed Source Stars
The Astronomical Journal, 2018
We present the analysis of microlensing event MOA-2010-BLG-117, and show that the light curve can only be explained by the gravitational lensing of a binary source star system by a star with a Jupiter mass ratio planet. It was necessary to modify standard microlensing modeling methods to find the correct light curve solution for this binarysource, binary-lens event. We are able to measure a strong microlensing parallax signal, which yields the masses of the host star, M * = 0.58 ± 0.11M , and planet m p = 0.54 ± 0.10M Jup at a projected star-planet separation of a ⊥ = 2.42±0.26 AU, corresponding to a semi-major axis of a = 2.9 +1.6 −0.6 AU. Thus, the system resembles a half-scale model of the Sun-Jupiter system with a half-Jupiter mass planet orbiting a half-solar mass star at very roughly half of Jupiter's orbital distance from the Sun. The source stars are slightly evolved, and by requiring them to lie on the same isochrone, we can constrain the source to lie in the near side of the bulge at a distance of D S = 6.9 ± 0.7 kpc, which implies a distance to the planetary lens system of D L = 3.5 ± 0.4 kpc. The ability to model unusual planetary microlensing events, like this one, will be necessary to extract precise statistical information from the planned large exoplanet microlensing surveys, such as the WFIRST microlensing survey.
The Astrophysical Journal, 2001
We present photometry and analysis of the microlensing alert MACHO 96-LMC-2 (event LMC-14 in ). This event was initially detected by the MACHO Alert System, and subsequently monitored by the Global Microlensing Alert Network (GMAN). The ∼ 3% photometry provided by the GMAN follow-up effort reveals a periodic modulation in the lightcurve. We attribute this to binarity of the lensed source. Microlensing fits to a rotating binary source magnified by a single lens converge on two minima, separated by ∆χ 2 ∼ 1. The most significant fit X1 predicts a primary which contributes ∼ 100% of the light, a dark secondary, and an orbital period (T ) of ∼ 9.2 days. The second fit X2 yields a binary source with two stars of roughly equal mass and luminosity, and T = 21.2 days.
OGLE-2016-BLG-1227L: A Wide-separation Planet from a Very Short-timescale Microlensing Event
The Astronomical Journal
We present the analysis of the microlensing event OGLE-2016-BLG-1227. The light curve of this shortduration event appears to be a single-lens event affected by severe finite-source effects. Analysis of the light curve based on single-lens single-source (1L1S) modeling yields very small values of the event timescale, t E ∼ 3.5 days, and the angular Einstein radius, θ E ∼ 0.009 mas, making the lens a candidate of a free-floating planet. Close inspection reveals that the 1L1S solution leaves small residuals with amplitude ∆I 0.03 mag. We find that the residuals are explained by the existence of an additional widely-separated heavier lens component, indicating that the lens is a wide-separation planetary system rather than a free-floating planet. From Bayesian analysis, it is estimated that the planet has a mass of M p = 0.79 +1.30 −0.39 M J and it is orbiting a low-mass host star with a mass of M host = 0.10 +0.17 −0.05 M ⊙ located with a projected separation of a ⊥ = 3.4 +2.1 −1.0 au. The planetary system is located in the Galactic bulge with a line-of-sight separation from the source star of D LS = 1.21 +0.96 −0.63 kpc. The event shows that there are a range of deviations in the signatures of host stars for apparently isolated planetary lensing events and that it is possible to identify a host even when a deviation is subtle.