Three researchers from the National Astronomical Research Institute of Thailand, the University of Lyon and the Sorbonne University (France) have discovered a third moon near the asteroid Elektra. This makes it the first quadruple asteroid system known to astronomers (Astronomy & AstrophysicsFebruary 8th).
Asteroid Elektra was discovered in 1873 by the German-American astronomer Christian Peters. The approximately 160-mile rocky object is part of the so-called main belt between the planets Mars and Jupiter. The first moon of Elektra was discovered in 2003, the second in 2014.
The existence of the third moon was revealed by examining archival data from a previous survey conducted with the European Very Large Telescope in Chile. To get a better picture of Elektra and its moons, the astronomers ‘cleaned up’ the old images using software and also processed them with an algorithm designed to suppress the glow of Elektra itself. After these operations, a previously unseen moon became visible.
The first moon of Elektra is about six kilometers in size and orbits at an average distance of 1300 kilometers around its ‘mother asteroid’. The second measures just two kilometers and traverses an elliptical orbit an average of 500 kilometers away. With a diameter of roughly a mile, the third moon is even slightly smaller. His distance to Elektra is estimated to be more than 300 kilometers.
It is still unclear how asteroids like Elektra get their moons. The most plausible explanation is that the moons formed from debris that was released during an impact on the parent asteroid. Another possibility is that the small objects have been ‘trapped’ by the relatively strong gravitational field of Elektra. (EE)
First quadruple asteroid system detected –
