Short-term variability of a sample of 29 trans-Neptunian objects and Centaurs - Astrophysics > Earth and Planetary AstrophysicsReport as inadecuate

Short-term variability of a sample of 29 trans-Neptunian objects and Centaurs - Astrophysics > Earth and Planetary Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We present results of 6 years of observations, reduced and analyzed with thesame tools in a systematic way. We report completely new data for 15 objects,for 5 objects we present a new analysis of previously published results plusadditional data and for 9 objects we present a new analysis of data alreadypublished. Lightcurves, possible rotation periods and photometric amplitudesare reported for all of them. The photometric variability is smaller thanpreviously thought: the mean amplitude of our sample is 0.1mag and only around15% of our sample has a larger variability than 0.15mag. The smallervariability than previously thought seems to be a bias of previousobservations. We find a very weak trend of faster spinning objects towardssmaller sizes, which appears to be consistent with the fact that the smallerobjects are more collisionally evolved, but could also be a specific feature ofthe Centaurs, the smallest objects in our sample. We also find that the smallerthe objects, the larger their amplitude, which is also consistent with the ideathat small objects are more collisionally evolved and thus more deformed.Average rotation rates from our work are 7.5h for the whole sample, 7.6h forthe TNOs alone and 7.3h for the Centaurs. All of them appear to be somewhatfaster than what one can derive from a compilation of the scientific literatureand our own results. Maxwellian fits to the rotation rate distribution givemean values of 7.5h for the whole sample and 7.3h for the TNOs only.Assuming hydrostatic equilibrium we can determine densities from our sampleunder the additional assumption that the lightcurves are dominated by shapeeffects, which is likely not realistic. The resulting average density is0.92g-cm^3 which is not far from the density constraint that one can derivefrom the apparent spin barrier that we observe.

Author: A. Thirouin, J.L. Ortiz, R. Duffard, P. Santos-Sanz, F.J. Aceituno, N. Morales



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