INDOZONE.ID – a asteroid The giant discovered in the 19th century has just been identified as the most crowded we astronomers have ever found.
This is called 130 Elektra, or Elektra for short. Astronomers have just discovered that it has not one, or two, but three companions satellite smaller ones, or moons.
That not only makes it the most abundant asteroid system known to date, but it also shows how we might find other faint, hard-to-see moons of asteroids in the future.
“Elektra is the first quadruple system ever detected,” wrote a team of astronomers led by Anthony Berdeu of the National Astronomical Research Institute of Thailand in their paper.
“This new detection, shows that special data reduction and processing algorithms that model the physics of the instrument can push the limits of contrast even further.”
It’s not a strange thing if asteroids have satellite friends smaller ones, though it’s rare to find them.
Of the more than 1,100,000 asteroids discovered, more than 150 are known to have at least one moon.
Elektra, measuring about 260 kilometers (160 mi), was first discovered in the asteroid belt between Mars and Jupiter in 1873, but its first moon, named S/2003 (130) 1, was only discovered in 2003 – 130 years later. S/2014 (130) 1, discovered in 2014.
There is a good reason why it took so long to find this satellite. Asteroids are small and only dim at the best of times.
Anything smaller that might orbit the asteroid will be dimmer, fainter, and possibly much brighter than its parent asteroid.
The smaller and closer the moon is to the asteroid, the harder it is to see. This is very similar to the reason why it is difficult to directly see exoplanets orbiting other stars.
S/2003 (130) 1 is only 6 kilometers in diameter, and orbits Elektra at an average distance of about 1,300 kilometers; S/2014 (130) 1 is only 2 kilometers in diameter, and has an average orbital distance of 500 kilometers.
The newly discovered moon is called S/2014 (130) 2, and is even smaller and closer: only 1.6 kilometers away, and at an average orbital distance of 340 kilometers. It is also 15,000 times fainter than Elektra.
To find it, Berdeu and his colleagues took archival data from the SPHERE instrument attached to the Southern European Observatory’s Very Large Telescope, and ran it through a newly developed data reduction pipeline to remove noise from the raw data with high efficiency.
They also used data-processing algorithms to help model the extended light around the asteroid, called a halo, and eliminate it.
After the data went through this process, the little third moon of Elektra appeared.
Although the team was able to obtain some basic information about S/2014 (103) 2, there is still a lot of uncertainty about its movement around Elektra. Other than that, we don’t have much information about how this system came into being.
A study last year found that the two moons of the asteroid named Cleopatra may have formed from dust ejected by the main asteroid, but we don’t know how common this would be compared to other formation mechanisms.
This may include rock ejected during an impact event, or even the capture of a small rock passing in the asteroid’s gravitational field.
“The discovery of the first quadruple asteroid system paved the way for understanding the mechanism of formation of these satellites,” the researchers wrote in their paper.
Additionally, their technique could be used in future studies to find more asteroid moons that could better explain the phenomenon.
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