After Dong carefully spliced early magnitudes from small cameras, the ASAS magnitudes, and the extensively observed waning portion, we could clearly see that the entire light curve really did conform in detail to the prediction based on microlensing
affects various emission regions of the disc in different ways, with smaller regions being more magnified.
Instead, it would be by using a space telescope to search for large numbers of microlensing
events--temporary brightenings caused by the slight gravitational focusing of starlight when a massive object passes between us and a background star.
In a paper submitted to Astronomy & Astrophysics, Patrick Tisserand (now at Australian National University) and 37 colleagues in the Experience pour la Recherche d'Objets Sombres (EROS)-2 collaboration published observations of microlensing
events toward the Large and Small Magellanic Clouds.
While the other two microlensing
planets have masses of a few times that of Jupiter, the discovery of a 5-Earth-mass planet--though much harder to detect than more massive ones--is a strong hint that these lower-mass objects are very common," says PLANET leader Jean-Philippe Beaulieu (Paris Astrophysical Institute), the first author of the discovery paper in the January 26th Nature.
This is an insightful question, because astronomers who use the gravitational microlensing
method to find extrasolar planets (the subject of our article) will indeed, in certain circumstances, see a single sharp peak added to the light curve.
The newly discovered planet is just the second one found by gravitational microlensing
, an effect predicted by Einstein's general theory of relativity (S&T: July 2004, page 18).
In 2002 the Polish OGLE III microlensing
survey detected suspicious periodic dimmings of a 17th-magnitude star in the direction of the galactic bulge.
to occur, however, the intervening object must pass extremely close to our line of sight to the background star, and this should happen very rarely.
Astronomers now routinely study microlensing
events in which background stars appear to vary in brightness over periods ranging from a day to several months.
The angular resolution provided by microlensing
is better than a microarcsecond," the researchers write.
For the discovery, the team used a technique called microlensing
-- a method capable of discovering planets at truly great distances from the Earth.