National Astronomical Research Institute of Thailand, University de Lyon and Sorbonne University scientists have made the first sighting of a quadruple asteroid system. It is an asteroid with three moons orbiting around it. The study has been published in the journal Astronomy and Astrophysics. Scientists described how they spotted a third moon around asteroid Elektra and some of its characteristics.
Astronomer Christian Peters has first seen the asteroid Elektra in 1873. The outer main-belt asteroid has been classified as a G-type, since then. It measures 260 kilometers across. It has a Ceres-like composition. Researchers found that it had a companion moon, in 2003. A second moon was found in 2014. Scientists have discovered a third moon. This is the system of a quadruple designation. This is the first ever observed.
Scientists studied archival data of a prior research of the Very Large Telescope in Chile. Scientists have analyzed the data. They focused on Elektra and its moons. They then ran it through a noise reduction software system. They also ran the data through an algorithm which has been designed to remove light from the halo surrounding objects like Elektra, to get an even better look. Result showed that there was a third moon orbiting the asteroid.
This surprised the scientists as none had ever been seen before. The first moon has been named S/2003 1. It has been measured as having a diameter of 6 kilometers. It orbits Elektra at an average distance of approximately 1,300 kilometers. The second moon has been named as S/2014 1. It is much smaller, with a diameter of just 2 kilometers.
It has an elliptical orbit much closer to Electra. The third moon has been named S/2014 2. It is smaller than the other two moons. It has a diameter of just 1.6 kilometers. Its orbit is more circular and closer to Elektra than the second moon. Its brightness was measured as 15,000 times less than the asteroid it is orbiting. It shows how remarkable it was that the astronomers were able to see it.