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Gravitational microlensing has emerged in recent years as an important method for
studying galactic dynamics. Microlensing occurs when a massive foreground
object, such as a star or burned out stellar core passes between us and
background star. Gravity has a tiny effect on the light rays as they come
toward us, and it bends some extra light toward us in much the same way as a
glass lens. The lensing action is not optically ideal, in that it tends to
distort the light into a ring-like image; however the increase in light can be
measured quite accurately.
Several tens of events have been detected toward the center of the galaxy, which is beginning to tell us more about the spatial distribution of massive objects within the galaxy and their distribution in mass. Some microlensing events have also been detected in the Large Magellanic Cloud, our satellite galaxy. These events are particularly exciting, because the sight-line toward the LMC cuts through the galactic halo, about which little is known. Preliminary results indicate that the masses of objects in the halo are of the order of half a solar mass, but more accurate models of the halo are needed for clearer interpretation. More recently, a new collaboration called PLANET observes lensing events many times a night after one of the two major search groups alerts them. With many observations per night, planetary companions to the lensing objects can be detected, and their mass estimated. Go To Page: 1
The copyright of the article Gravitational Microlensing in Astronomical Events is owned by . Permission to republish Gravitational Microlensing in print or online must be granted by the author in writing.
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