Centaurs are rare space objects that can combine some of the different characteristics of asteroids and comets. They are rocky in nature, like asteroids, but can also emit clouds of dust and gas when their outer parts evaporate like comets.
When centaurs emit these gases, they are considered active. We've only found 18 chemically active centaurs in history, but now a new one has been added to the list – and he may be able to tell us more about how these mysterious flying stones develop their unique characteristics.
Keeping a close eye on the centaurs is a huge problem – they are very far away, orbiting the wrong trajectory, and taking up a lot of telescope time. But in this case, the researchers examined archival images and also used new data collected by the Inter-American Observatory and the Walter Baade Telescope at the Las Campanas Observatory in Chile.
“We have developed a new technique that combines observations – such as the color and mass of dust – with simulations to evaluate characteristics such as volatile sublimation of an object and orbital dynamics,” says astronomer Colin Chandler of Northern Arizona University.
This method, which includes a specially designed algorithm to search for traces of activity in existing satellite images, has revealed evidence that the Centaur 2014 OG392 converted solids to gases (sublimation) and left behind a long comet-like halo.
Based on new observations made over the past two years, it seems clear that this particular centaur is special. Then, computer simulations helped astronomers figure out what types of ice could burn on the rock.
This is not an easy calculation, not least because the asteroid is likely not made of one type of ice, but a mixture of materials that can burn in different ways. However, the researchers think they have figured out what is happening and what may be happening with other similar objects.
'We found a coma 400,000 km away from 2014 OG392,' says Chandler, 'and our analysis of sublimation and dynamics suggests that carbon dioxide and / or ammonia are the most likely candidates to induce activity in this and other active centaurs'.
A coma is a shell of ice and cometary dust that forms around a comet's nucleus as it passes close to the Sun. Comets look indistinct due to coma.
These types of objects and the like are believed to have remained virtually unchanged since the early days of the solar system, which means they are incredibly useful as time capsules for studying how our planets formed and settled into their orbits.
The study was published in Astrophysical Journal Letters.
Credits: Photo: This image shows the bright coma of C / 2014 OG392 (PANSTARRS). (Northern Arizona University)
