Substellar Companion Discovered With Microlens

Astronomers used a gravitational microlensing technique and found a substellar companion of a host star in the MOA-2012-BLG-006L system. It is an object that may be a high-mass giant planet or a low-mass brown dwarf. The study was published April 4 on the arXiv pre-print server.

The gravitational lens effect is useful as the microlensing method. It helped to locate the substellar companion, but can also help to locate planetary and stellar-mass objects. The light they emit does not impact the study. Hence, the technique used identifies the mass not the luminosity of the object, according to phys.org. The astronomers are able to study even those objects that emit little or no light at all.

Microlensing can help scientists to locate planets that orbit stars near the center of the galaxy even if the planets are located thousands of light-years away. Other radial velocity searches identify planets only in our much closer galactic neighborhood, according to Planetary.org.

The latest analysis of the observational data was offered by the 1.3m telescope at Las Campanas Observatory in Chile, the 1.8m telescope at Mt. John Observatory in New Zealand and the Keck-II telescope in Hawaii. They gave a lot of hints regarding the properties of the system. Researchers were led by Radosław Poleski of the Warsaw University Observatory in Poland. Recent data made them arrive at the conclusion that the substellar companion in MOA-2012-BLG-006L is either a giant planet or a brown dwarf.

"We present the discovery of a substellar companion to the primary host lens in the microlensing event MOA-2012-BLG-006," the scientists wrote in the paper.

The substellar companion is 8.4 times bigger than Jupiter, even as its host has half the mass of the sun. The scientists said that the MOA-2012-BLG-006Lb can be classified depending on the mass. It could be viewed as a planet or a brown dwarf, "if its mass is at the high end of the derived distribution." Their discovery could help us to understand the mechanisms that led to the formation of objects such as those that operate like others in the solar neighborhood as well as in remote parts of the Milky Way galaxy. The microlensing method can identify these objects, and helped the astronomers to arrive at the substellar companion.