If the source star is a binary star , then it too will have a non-linear motion which can also cause slight, but detectable changes in the light curve.
This effect is known as Xallarap parallax spelled backwards. If the lensing object is a star with a planet orbiting it, this is an extreme example of a binary lens event. If the source crosses a caustic, the deviations from a standard event can be large even for low mass planets. These deviations allow us to infer the existence and determine the mass and separation of the planet around the lens. Deviations typically last a few hours or a few days.
Because the signal is strongest when the event itself is strongest, high-magnification events are the most promising candidates for detailed study.
Neal Dalal | Perimeter Institute
Typically, a survey team notifies the community when they discover a high-magnification event in progress. Follow-up groups then intensively monitor the ongoing event, hoping to get good coverage of the deviation if it occurs.
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When the event is over, the light curve is compared to theoretical models to find the physical parameters of the system. The parameters that can be determined directly from this comparison are the mass ratio of the planet to the star, and the ratio of the star-planet angular separation to the Einstein angle. From these ratios, along with assumptions about the lens star, the mass of the planet and its orbital distance can be estimated. Combining their data, they found the most likely planet mass to be 1. This record was contested in by Gliese c with a minimal mass of 5 Earth masses, and since Gliese e is the lightest known "regular" exoplanet, with minimum 1.
Comparing this method of detecting extrasolar planets with other techniques such as the transit method, one advantage is that the intensity of the planetary deviation does not depend on the planet mass as strongly as effects in other techniques do.
Ikerbasque Research Professor, UPV/EHU
This makes microlensing well suited to finding low-mass planets. It also allows detection of planets further away from the host star than most of the other methods. One disadvantage is that followup of the lens system is very difficult after the event has ended, because it takes a long time for the lens and the source to be sufficiently separated to resolve them separately.
There are two basic types of microlensing experiments. There are current proposals to build new specialized microlensing satellites, or to use other satellites to study microlensing. From Wikipedia, the free encyclopedia. Part of a series of articles about Gravitational lensing Einstein ring Formalism Strong lensing Microlensing Weak lensing Strong lens systems. Gravitational Lensing: Strong, Weak and Micro.
Dark Matter in Astro- and Particle Physics
Saas-Fee Lectures, Springer-Verlag. Saas-Fee Advanced Courses. The Astrophysical Journal. Bibcode : ApJ Energy profile of the accretion disk". Monthly Notices of the Royal Astronomical Society. Nature Astronomy. Bibcode : NatAs Astrophysical Journal. Astronomy and Astrophysics.
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Authority control LCCN : sh Categories : Effects of gravitation Gravitational lensing.
It may hold the key to understanding the mysterious 25 percent of the universe that acts as an invisible source of gravity holding galaxies together and influencing the motion of stars. Back in in the second issue of symmetry , we ran an "Explain it in 60 seconds" about gravitational lensing in which postdoc Phil Marshall described his very geeky party trick of using a wine glass to help explain gravitational lensing, the topic of this new Duke work. That gravitational lensing in a wine glass experiment also shows the light curves known as caustics along with the multiple images caused by gravitational lenses.
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- Gravitational microlensing.
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Perhaps all the secrets to the universe can be found in the crockery and glassware of the dinner table! Update : Thanks to kristazala for a great alternative title for this story in a tweet: "Coffee chiaroscuro explains dark matter in a light roast". Skip to main content Skip to table of contents. Advertisement Hide. Editors view affiliations H.
Conference proceedings. Front Matter Pages Pages Dark Matter Caustics. Contribution to Dark Matter from Extragalactic Dust.
Astrophysical Axion Bounds. Can Dark Matter See Itself? Can Quintessence Be Natural? Preheating, Thermalization and Supergravity. Big Bang Nucleosynthesis and Related Observations.