Physical properties of the extreme Centaur and super-comet candidate 2013 AZ₆₀

November 2015 • 2015A&A...583A..93P

Authors • Pál, A. • Kiss, Cs. • Horner, J. • Szakáts, R. • Vilenius, E. • Müller, Th. G. • Acosta-Pulido, J. • Licandro, J. • Cabrera-Lavers, A. • Sárneczky, K. • Szabó, Gy. M. • Thirouin, A. • Sipőcz, B. • Dózsa, Á. • Duffard, R.

Abstract • We present estimates of the basic physical properties including size and albedo of the extreme Centaur 2013 AZ₆₀. These properties have been derived from optical and thermal infrared measurements. Our optical measurements revealed a probable full period of ≈9.4 h with a shallow amplitude of 4.5%. By combining optical brightness information and thermal emission data, we are able to derive a diameter of 62.3 ± 5.3 km and a geometric albedo of 2.9%, which corresponds to an extremely dark surface. Additionally, our finding of ≳50 Jm^-2 K^-1 s^{- 1/2} for the thermal inertia is also remarkable for objects in such a distance. The results of dynamical simulations yield an unstable orbit, with a 50% probability that the target will be ejected from the solar system within 700 000 yr. The current orbit of this object and its instability could imply a pristine cometary surface. This possibility agrees with the observed low geometric albedo and red photometric colour indices for the object, which match the surface of a dormant comet well, as would be expected for a long-period cometary body approaching perihelion. Although it was approaching ever closer to the Sun, however, the object exhibited star-like profiles in each of our observations, lacking any sign of cometary activity. According to the albedo, 2013 AZ₆₀ is a candidate for the darkest body among the known trans-Neptunian objects.

Links

• POSTSCRIPT https://www.aanda.org/10.1051/0004-6361/201526249/postscript
• PDF https://www.aanda.org/10.1051/0004-6361/201526249/pdf
• PREPRINT http://arxiv.org/abs/1507.05468
• DATA http://archives.esac.esa.int/hsa/whsa/?ACTION=PUBLICATION&ID=2015A%26A...583A..93P
• DATA https://irsa.ipac.caltech.edu/bibdata/2015/P/2015A&A...583A..93P.html
• ELECTR https://doi.org/10.1051%2F0004-6361%2F201526249