Special comet sheds light on the solar system’s formation
Using powerful ground-based telescopes, researchers have discovered an unusual object which appears to be made of inner Solar System material dating back to the time of Earth’s formation, and their work could shed new light on the origins of the sun and its planets.
Writing in Friday’s edition of the journal Science Advances, Karen J. Meech from the University of Hawaii’s Institute for Astronomy and her colleagues reported that they had used the European Southern Observatory’s Very Large Telescope and the Canada France Hawaii Telescope to find an object that had the characteristics of a pristine inner Solar System asteroid.
The object, identified as C/2014 S3 (PANSTARRS), is the first such object every to be found on a long-period cometary orbit, the researchers explained in a statement. It is made of material that dates back to the era of Earth’s formation, and which had been preserved for several billion years in the Oort Cloud, a group of icy planetesimals located up to three light years from the sun.
The study authors believe that C/2014 S3 (PANSTARRS) formed in the inner Solar System at the same time as the Earth, but that this ancient rocky object was expelled at an early age. The body could be one of the building blocks of rocky planets like the Earth, and was likely ejected to the far reaches of the solar system, where it was frozen and preserved in the Oort Cloud.
“We already knew of many asteroids, but they have all been baked by billions of years near the Sun,” Meech, the lead author of the paper, said of the discovery. “This one is the first uncooked asteroid we could observe: it has been preserved in the best freezer there is.”
Findings could lead to testing of solar system formation theories
Originally identified by the Pan-STARRS1 telescope as a weakly-active comet that has an orbital period of approximately 860 years, it has recently (in astronomical terms, at least) entered into an orbit that brought it closer to the sun, which revealed many usual features of the object.
For instance, the researchers found that, unlike most long-period comets which travel close to the sun, C/2014 S3 (PANSTARRS) lacks a tail, causing them to nickname it the “Manx comet” after the species of tailless cat. An analysis of the light reflected by the object revealed that it is typical of S-type asteroids, which are typically found in the inner asteroid main belt.
Typically, comets are believed to form in the outskirts of the Solar System and tend to be icy, not rocky, Meech’s team noted. In the case of C/2014 S3 (PANSTARRS), they believe it is made out of material that has undergone has been in a deep freeze for a very long period of time and which has undergone very little processing as a result. Furthermore, they believe that the sublimation of water is the reason for the weak comet-like activity associated with the object.
The discovery of this so-called rocky comet will enable researchers to test different predictions of the theoretical models used to explain the origins of the solar system, but the authors caution that at least 50 to 100 of these objects will need to be analyzed in order to do so.
“We’ve found the first rocky comet, and we are looking for others,” Olivier Hainaut, co-author of the study and a researcher with the ESO, said in a statement. “Depending how many we find, we will know whether the giant planets danced across the Solar System when they were young, or if they grew up quietly without moving much.”
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Image credit: ESO
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