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Millimeter & Submillimeter Astronomy Group
at the Max-Planck-Institut für Radioastronomie
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Small Bodies in the Solar System
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Small Bodies in the Solar System
At far-infrared to millimeter wavelengths the thermal emission of an asteroid is in equilibrium with the solar
irradiation. This allows us to derive its size from the observed flux density and combined with optical data, also
its albedo. Using MAMBO at the IRAM 30m telescope we were engaged in an effort to detect the 1.2 mm emission of
newly detected Centaurs and EKOs. In the winter 1999/2000 Centaur Chariklo was the brightest of all distant asteroids,
and we were able to detect it with MAMBO, deriving a mean diameter of 275 km and a geometric albedo of 5.5 %. In a
collaborative effort led by a group from Caltech we have since detected, first at optical wavelengths and then with
MAMBO at 1.2 mm, the two largest KBOs known, 2002AW197 and Quaoar. Their estimated diameters are 900 and 1300 km and
their respective albedos 10% and 13%.
Millimeter continuum observations of Comets
We have been utilizing the high sensitivity of MAMBO at the IRAM 30m telescope to detect thermal emission from
the particle halo around comets. With such measurements we can study the particle size distribution and the total
particle mass in the halo and indirectly derive the nuclear diameter and mass. During the past two years we were able
to detect thermal emission from three comets.
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