Zee Media Bureau
New Delhi: According to a new research funded by NASA, astronomers have found in the far world first signs of what could be an “exomoon”.
An “exomoon” is a moon orbiting a planet that lies outside the solar system.
About 850 extrasolar planets-planets outside the solar system-are known, and most of them are sterile gas giants, similar to Jupiter.
The international study is led by the joint Japan-New Zealand-American Microlensing Observations in Astrophysics (MOA) and the Probing Lensing Anomalies NETwork (PLANET) programs, using telescopes in New Zealand and Tasmania.
The astronomers used a technique called gravitational microlensing, in which one star passes in front of another as seen from Earth. The closer star can act like a magnifying glass to focus and brighten the light of the more distant one for a period of days-to weeks during the event.
In the new study, the nature of the foreground lensing object is not clear. The ratio of the larger body to its smaller companion is 2,000 to 1. That means the pair could be either a small, faint star circled by a planet about 18 times the mass of Earth-or a planet more massive than Jupiter coupled with a moon weighing less than Earth.
The problem is that astronomers have no way of telling which of these two scenarios is correct.
The answer to the mystery lies in learning the distance to the circling duo. A lower-mass pair closer to Earth will produce the same kind of brightening event as a more massive pair located farther away. But once a brightening event is over, it's very difficult to take additional measurements of the lensing system and determine the distance. The true identity of the exomoon candidate and its companion, a system dubbed MOA-2011-BLG-262 , will remain unknown.
The study has been published in the Astrophysical Journal.
(With Agencies inputs)
First Published: Friday, April 11, 2014, 09:53
