Astronomers discovered the first quadruple asteroid: Electra from the Main Belt, which now has a third satellite.
The newly discovered object is more than a hundred times smaller than the parent body and makes one revolution around it in less than a day.
The first satellite near the asteroid was found in 1993: Dactyl, which is 20 times smaller than the Main Belt asteroid (243) Ida, around which it revolves.
To date, scientists know 190 multiple asteroid systems and even bodies with rings. Studies of such systems allow us to understand how they formed and evolved.
Asteroid (130) Electra was discovered on February 17, 1873 by astronomer Christian Peters and is located in the main asteroid belt.
This is a large object with an effective diameter of 199 kilometers and a mass of 7 × 1018 kilograms.
In 2003, the Keck Observatory telescope discovered the S/2003 (130) 1 satellite near Elektra, which has a diameter of 6 kilometers and is in a 5.3-day orbit around the parent body, at a distance of 1300 kilometers from it.
The second satellite, designated S/2014 (130) 1, was discovered in 2014 using the VLT complex.
It has a diameter of about 2 kilometers and makes one orbit around Electra in 1.2 days, being at a distance of 500 kilometers.
Now, a team of astronomers led by Anthony Berdeu of the National Institute for Astronomical Research of Thailand announced the discovery of the third satellite of Elektra, designated S/2014 (130) 2.
The discovery was made using new methods of processing observations from the SPHERE (Spectro-Polarimetric) receiver.
This instrument is located at the High-contrast Exoplanet REsearch facility installed on the VLT complex, which monitored Elektra in 2014.
The orbital period of the new satellite is 0.679 days, the semi-major axis of its orbit is 344 kilometers, and the orbital eccentricity is 0.33.
Its brilliance is 15 thousand times less than that of the parent body, and its diameter is estimated at 1.6 ± 0.4 kilometers.
Thus, Elektra became the first known quadruple asteroid, and further observations of it will allow us to refine the orbits of all three satellites and test models of the system's formation.
Source:
Astronomy & Astrophysics: https://www.aanda.org/articles/aa/full_html/2022/02/aa42623-21/aa42623-21.html
Sciencealert: https://www.sciencealert.com/this-is-the-first-asteroid-ever-discovered-to-have-three-moons