Video: See how the space rock鈥檚 shiny rings were found
Asteroids with Saturn-envy can deck themselves out with glittering rings. A space rock called 10199 Chariklo is the first asteroid known to have a ring system, revealing an unexpected possibility for small bodies in the solar system. Until now, rings have been found only around giant planets.
of the Max Planck Institute for Solar System Research in G枚ttingen, Germany, and his colleagues found the rings in June 2013 during an asteroid occultation. This is when a space rock crosses in front of a star as seen from Earth, causing the star to briefly wink out. Seen from sites across South America, the star鈥檚 brightness dipped in a distinctive pattern, indicating a set of sharply defined, thin rings.
鈥淲e were amazed to see that the star didn鈥檛 just blink out and come back 鈥� there were very short blinks before and after the main dip, which could only be explained by rings,鈥� says Snodgrass.
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Hidden shepherds
Usually the particles in rings would spread out, making them smoother at the edges. To look so sharp, the asteroid鈥檚 rings must be constantly shaped by something, most likely unseen 鈥渟hepherd鈥� satellites that move near the rings and keep their particles confined. 鈥淪hepherds have been observed around some of Uranus and Saturn鈥檚 narrow rings,鈥� says team member Bruno Sicardy at Pierre-and-Marie-Curie University in Paris, France. 鈥淪o even if their origins are very different, Chariklo鈥檚 rings seem to follow some common rules.鈥�
Chariklo orbits between the paths of Saturn and Uranus, and the asteroid has shown mysterious behaviour in the past. The tiny body was seen dimming and brightening, and its spectrum held hints of water ice disappearing and reappearing. A pair of icy, reflective rings seen from different angles would account for this.
The authors think the rings could have formed in a number of ways, including impacts flinging up debris, or small moons colliding or being broken up by gravity if they spiralled too close to the asteroid.
鈥淭his work is very consistent with all previous data, and provides an explanation which is quite unexpected,鈥� says of the European Space Research and Technology Centre in the Netherlands, who did not contribute to the study. 鈥淚t opens a new and unique perspective on the processes dominating the history of small bodies.鈥�
Journal reference: Nature, DOI: 10.1038/nature13155
