Volume 583, November 2015
|Number of page(s)||8|
|Section||Planets and planetary systems|
|Published online||02 November 2015|
Physical properties of the extreme Centaur and super-comet candidate 2013 AZ60
Konkoly Observatory, MTA Research Centre for Astronomy and Earth Sciences,
Konkoly-Thege Miklós út 15–17, 1121
2 Department of Astronomy, Loránd Eötvös University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
3 Computational Engineering and Science Research Centre, University of Southern Queensland, Toowoomba, 4350 Queensland, Australia
4 Australian Centre for Astrobiology, UNSW Australia, Sydney, 2052 New South Wales, Australia
5 Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, Giessenbachstr., 85741 Garching, Germany
6 Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
7 Instituto de Astrofísica de Canarias, 38205, La Laguna, Tenerife, Spain
8 Departamento de Astrosfísica, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain
9 Gothard Astrophysical Observatory, Loránd Eötvös University, 9700 Szombathely, Hungary
10 Lowell Observatory, 1400 W Mars Hill Rd, Arizona, AZ 86001, USA
11 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
12 Instituto de Astrofísica de Andalucía – CSIC, Apt 3004, 18008 Granada, Spain
Received: 2 April 2015
Accepted: 7 July 2015
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.
Key words: Kuiper belt objects: individual: 2013 AZ60 / radiation mechanisms: thermal / techniques: photometric
© ESO, 2015
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