Microlensing takes advantage of an effect predicted by Albert Einstein in the early 1900s.
When a star passes precisely in front of another star, the gravity of the star in front bends and amplifies the light from the background star. Any planets circling the star in front create detectable anomalies.
As for the speed and decisiveness of the discovery, the researchers credit the wide field of view of the MOA-II telescope in New Zealand, which allows the Milky Way's entire galactic bulge to be imaged every hour.
But the process leaves some details unanswered, such as the exact mass of the host star.
The star could be 6 percent the mass of our sun, and thus a brown dwarf—or it could be 9 percent, which would make it a red dwarf. Red dwarfs are about a hundred times brighter than brown dwarfs but a thousand times fainter than the sun.
Bennett said future observations will be aimed at teasing out more about the host, including whether it has additional planets in its habitable zone.
Illuminating Brown Dwarfs
Also at the conference, Michael Liu, an astronomer at the University of Hawaii, said that the ground-based W.M. Keck Observatory and the Hubble Space Telescope are allowing new views of brown dwarfs as small as 3 percent the mass of the sun.
"They're easy to study in great detail, because they're floating close to Earth," Liu said.
Brown dwarfs hold insights into the nature of gas giants like Jupiter and Saturn, because they are the missing links between the lowest-mass stars and gas-giant planets, he said.
Liu said the latest telescope optics are allowing razor-sharp views of these prohibitively faint objects.
"If your eyes were as sharp as the Keck telescope," he said during the briefing, "you would be able to read a magazine pasted on the St. Louis arch, about a mile [1.6 kilometers] away" from the conference site.
That clarity is shedding light not just on brown dwarfs, but on the flaws in the science surrounding them, he said.
In short, the current models are off, and the telescopes are sending theorists back to the drawing board.
The current models, for example, are either "not predicting the right temperature and/or the right amount of energy," Liu said.
|
SOURCES AND RELATED WEB SITES
|
