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The longest microlensing events provide enough information to estimate the mass and distance of the lens. Among hundreds of millions of stars which were monitored for many years by the OGLE project we selected those with clear parallax…

Solar and Stellar Astrophysics · Physics 2016-01-13 Łukasz Wyrzykowski , Zuzanna Kostrzewa-Rutkowska , Krzysztof Rybicki

Over the past decade, microlensing has developed into a powerful tool to study stellar astrophysics, especially stellar atmospheres, stellar masses, and binarity. I review this progress. Stellar atmospheres can be probed whenever the source…

Astrophysics · Physics 2016-08-30 Andrew Gould

We show that the statistical error, $\sigma_{\tau}$, in estimating the optical depth, $\tau$, due to microlensing is substantially higher than the naive Poisson estimate: $\sigma_{\tau} = \sqrt{\eta / N} \tau$, where $N$ is the number of…

Astrophysics · Physics 2009-10-22 Cheongho Han , Andrew Gould

We analyze the data of the gravitational microlensing survey carried out by by the MOA group during 2000 towards the Galactic Bulge (GB). Our observations are designed to detect efficiently high magnification events with faint source stars…

Astrometric microlensing can be used to make precise measurements of the masses of lens stars that are independent of their assumed internal physics. Such direct mass measurements, obtained purely by observing the gravitational effects of…

Solar and Stellar Astrophysics · Physics 2018-10-17 D. M. Bramich

I demonstrate that one can detect pixel gravitational microlensing events at the rate $\sim 180\ {\rm events}\ {\rm yr}^{-1}$ and that some fraction of events ($\sim 15$) will be good enough to measure time scales at the $20\%$ level if the…

Astrophysics · Physics 2009-10-28 Cheongho Han

Microlensing events are now regularly being detected by monitoring the flux of a large number of potential sources and measuring the combined magnification of the images. This phenomenon could also be detected directly from the…

Astrophysics · Physics 2009-10-28 Jordi Miralda-Escude

To provide criteria in the selection of target events preferable for planetary lensing follow-up observations, we investigate the variation of the probability of detecting planetary signals depending on the observables of the lensing…

Astrophysics · Physics 2009-06-23 Cheongho Han

We analyse the effects on the predictions for the microlensing searches toward the Galactic bulge coming from the fact that not all the stars monitored belong to the bulge itself, but that a non--negligible fraction of them actually are in…

Astrophysics · Physics 2009-10-28 S. Mollerach , E. Roulet

A microlensing event is mainly used to search for free-floating planets (FFPs). To estimate the FFP mass and distance via the microlensing effect, a microlensing parallax is one of the key parameters. A short duration of FFP microlensing is…

Earth and Planetary Astrophysics · Physics 2024-07-31 Makiko Ban

Gould & DePoy proposed a pixel lensing survey towards the Galactic bulge using a small aperture (~65 mm) camera with a large pixel size (10") detector and deliberately degraded optics achieving 30" PSF. In this paper, we estimate the event…

Astrophysics · Physics 2009-11-06 Cheongho Han

Ongoing microlensing surveys have already yielded more than five hundred microlensing events, most of which have been identified in real-time. In this review I present the basic theory and observational status of these surveys. I highlight…

Astrophysics · Physics 2007-05-23 Shude Mao

Much interest has been generated recently by the ongoing MACHO, EROS and OGLE projects to identify gravitationally lensed stars from the Large Magellanic Cloud and Galactic bulge, and the positive identification of several events (Alcock et…

Astrophysics · Physics 2007-05-23 J. F. L. Simmons , J. P. Willis , A. Newsam

Perhaps as many as 30 parallax microlensing events are known, thanks to the efforts of the MACHO, OGLE, EROS and MOA experiments monitoring the bulge. Using Galactic models, we construct mock catalogues of microlensing light curves towards…

Astrophysics · Physics 2009-11-11 M. C. Smith , V. Belokurov , N. W. Evans , S. Mao , J. H. An

Stellar microlensing is a powerful method to constrain compact dark matter models, uncover binary stars, and exoplanets during caustic crossing events. At cosmological distances, {\it James-Webb Space Telescope} ({\it JWST}) is routinely…

Astrophysics of Galaxies · Physics 2026-04-14 Sung Kei Li , Thomas Broadhurst , Jose M. Diego , Jeremy Lim , Jose M. Palencia , James Nianias

Microlensing light curves are now being monitored with the precision required to detect small perturbations due to planetary companions of the primary lens. Microlensing is complementary to other planetary search techniques in its potential…

Astrophysics · Physics 2009-10-31 B. Scott Gaudi , Penny D. Sackett

Microlensing events can be used to directly measure the masses of single field stars to a precision of $\sim$1-10\%. The majority of direct mass measurements for stellar and sub-stellar objects typically only come from observations of…

Solar and Stellar Astrophysics · Physics 2018-11-09 M. B. Nielsen , D. M. Bramich

The detection of microlensing events from stars in the Large Magellanic Cloud and in the Galactic bulge raise important constraints on the distribution of dark matter and on galactic structure, although some events may be due to a new type…

Astrophysics · Physics 2020-11-25 David Valls-Gabaud

We determine the microlensing event rate distribution, $\Gamma(t_{E})$, that is properly normalized by the first year MACHO group observations (Alcock et al. 1997). By comparing the determined $\Gamma(t_{E})$ with various MF models of lens…

Astrophysics · Physics 2007-05-23 Cheongho Han , Seunghun Lee

Galactic model plays an important role in the microlensing field, not only for analyses of individual events but also for statistics of the ensemble of events. However, the Galactic models used in the field varies, and some are…

Astrophysics of Galaxies · Physics 2021-02-24 Hongjing Yang , Shude Mao , Weicheng Zang , Xiangyu Zhang