[ad_1]
New observations of a dog-bone-shaped asteroid and its two tiny moons have given scientists an understanding of how the bizarre trio came to be.
An astronomer first spotted the Kleopatra space rock among other space rocks in the asteroid belt between Mars and Jupiter in 1880, but in recent decades scientists have realized that the main space rock has a shape strange and two tiny moons. And the researchers suggested this was not the end of Cleopatra’s surprises. Thus, a team of scientists arranged to study space rock using the Very Large Telescope based in Chile.
“Kleopatra is truly a unique body in our solar system,” said Franck Marchis, an astronomer at the SETI Institute in California and at the Astrophysics Laboratory in Marseille, France, who has led new research on the asteroid, in a statement.
“Science is making a lot of progress through the study of weird outliers,” he added. “I think Cleopatra is one of those, and understanding this complex and multiple asteroid system can help us learn more about our solar system.”
Related: The greatest asteroid encounters of all time!
Read more: The 7 strangest asteroids in the solar system
In 2008, Marchis and his colleagues spotted Cleopatra’s two moons, AlexHelios and CleoSelene, named after two children of ancient Egypt’s most famous queen. But even after the discovery, scientists wanted to keep an eye on the system – and sighting the asteroid from 2017 to 2019 sharpened the picture for Kleopatra researchers.
These new observations come from the SPHERE instrument (Spectro-Polarimetric High Contrast Exoplanet Research) of the Very Large Telescope. As the name suggests, the instrument was originally developed to spot extraterrestrial planets, according to the European Southern Observatory (ESO), which operates the facility. This research requires spotting dark exoplanets around bright stars. SPHERE is therefore well placed to spot the tiny moons orbiting Cleopatra’s shining main body 200 million kilometers from Earth.
And conveniently enough, the instrument is also equipped with a high-power adaptive optics system to adjust images to the blur that Earth’s atmosphere otherwise causes. The result is razor-sharp photographs, even inside the solar system.
The researchers therefore used SPHERE to take a series of images of Cleopatra. Because the images were so crisp, scientists could use them to refine models of Cleopatra’s hunk and to determine how the two moons AlexHelios and CleoSelene orbit the larger body.
In the process, the researchers determined that the previous orbital models for these two small moons were incorrect. This is a big deal, as scientists use the relationship between a body and its moons to understand the gravity involved and in turn the mass of the asteroid.
“This had to be resolved,” Miroslav Brož, a solar system scientist at Charles University in the Czech Republic, said in the statement. “Because if the orbits of the moons were wrong, everything was wrong, including Cleopatra’s mass.”
With the new orbital data, scientists have determined that Kleopatra is about 35% less massive than previous calculations estimated. The new value, along with refined models of the asteroid’s size, suggest the asteroid is not as dense as scientists had believed, despite scientists believing the object to be metallic. This paradox suggests that Kleopatra has a “rubble heap” structure with many gaps, much like the asteroids Ryugu and Bennu that spacecraft have visited for close study in recent years.
The rubble-pile asteroids likely formed from the fusion of debris after a giant impact, but the new analysis also suggests that AlexHelios and CleoSelene were from Kleopatra herself. This theory is based on the determination that Cleopatra is spinning so fast that if she accelerated a lot, she would simply fall apart. According to the researchers, this means that even collisions with small rubble could remove pebbles from the main asteroid’s surface which could then blend into moons.
And scientists have yet to rule out that there may be other tiny moons orbiting Cleopatra. However, researchers will have to wait for more powerful instruments to see such organs. One possible tool will be ESO’s extremely large telescope, or ELT, which is slated for sighting later this decade.
“I can’t wait to point the ELT at Cleopatra, see if there are more moons, and refine their orbits to detect small changes,” Marchis said.
The research is described in two articles published Thursday, September 9 in the journal Astronomy & Astrophysics.
Email Meghan Bartels at [email protected] or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.
[ad_2]
Source link