``TNOs are Cool'': A survey of the trans-Neptunian region. I. Results from the Herschel science demonstration phase (SDP)
2 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
3 UoA - University of Arizona
4 Konkoly Observatory
5 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
6 Observatoire de la Côte d'Azur
7 LAM - Laboratoire d'Astrophysique de Marseille
8 IAA-CSIC - Instituto de Astrofísica de Andalucía = Institute of Astrophysics of Andalusia
9 DLR - Deutsches Zentrum für Luft- und Raumfahrt
10 Department of Physics [Durham University]
11 QUB - Queen's University [Belfast]
12 Space Science and Technology Department, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon UK
13 Northern Arizona University [Flagstaff]
14 OAR - INAF - Osservatorio Astronomico di Roma
15 ESO - European Southern Observatory
16 IMCCE - Institut de Mécanique Céleste et de Calcul des Ephémérides
17 GAP - Groupe Astrométrie et Planétologie
18 Herschel Science Center, ESAC/ESA
19 UNIBE - Universität Bern = University of Bern = Université de Berne
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Résumé
The goal of the Herschel open time key programme ``TNOs are Cool!'' is to derive the physical and thermal properties for a large sample of Centaurs and trans-Neptunian objects (TNOs), including resonant, classical, detached and scattered disk objects. We present results for seven targets either observed in PACS point-source, or in mini scan-map mode. Spitzer-MIPS observations were included for three objects. The sizes of these targets range from 100 km to almost 1000 km, five have low geometric albedos below 10%, (145480) 2005 TB190 has a higher albedo above 15%. Classical thermal models driven by an intermediate beaming factor of eta = 1.2 or eta-values adjusted to the observed colour temperature fit the multi-band observations well in most cases. More sophisticated thermophysical models give very similar diameter and albedo values for thermal inertias in the range 0-25 J m-2 s-0.5 K-1, consistent with very low heat conductivities at temperatures far away from the Sun. The early experience with observing and model strategies will allow us to derive physical and thermal properties for our complete Herschel TNO sample of 140 targets as a benchmark for understanding the solar system debris disk, and extra-solar ones as well.