Astronomy and Astrophysics – Astrophysics – Earth and Planetary Astrophysics
Scientific paper
2009-02-26
Astronomy and Astrophysics
Astrophysics
Earth and Planetary Astrophysics
52pages, 15 figures, accepted by AJ February 24 2009
Scientific paper
10.1088/0004-6256/137/5/4296
The Centaurs are recent escapees from the Kuiper belt that are destined either to meet fiery oblivion in the hot inner regions of the Solar system or to be ejected to the interstellar medium by gravitational scattering from the giant planets. Dynamically evolved Centaurs, when captured by Jupiter and close enough to the Sun for near-surface water ice to sublimate, are conventionally labeled as "short-period" (specifically, Jupiter-family) comets. Remarkably, some Centaurs show comet-like activity even when far beyond the orbit of Jupiter, suggesting mass-loss driven by a process other than the sublimation of water ice. We observed a sample of 23 Centaurs and found nine to be active, with mass-loss rates measured from several kg/s to several tonnes/s. Considered as a group, we find that the "active Centaurs" in our sample have perihelia smaller than the inactive Centaurs (median 5.9 AU vs. 8.7 AU), and smaller than the median perihelion distance computed for all known Centaurs (12.4 AU). This suggests that their activity is thermally driven. There are several possibilities for the origin of the mass-loss from the active Centaurs. We consider the possibility that activity in the Centaurs is triggered by the conversion of amorphous ice into the crystalline form accompanied by the release of trapped gases, including carbon monoxide. By imposing the condition that crystallization should occur when the crystallization time is shorter than the orbital period we find a qualitative match to the perihelion distribution of the active Centaurs and conclude that the data are consistent with the hypothesis that the Centaurs contain amorphous ice.
No associations
LandOfFree
The Active Centaurs does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Active Centaurs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Active Centaurs will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-570916