The size and albedo of KBO 2002 AW197
Abstract
The discovery of the Kuiper belt object 2002 AW197 by Trujillo and Brown in January 2002 was announced in MPEC 2002-O30. We measured the diameter and albedo of this object by combining measurements of its reflected light and thermal emission. Photometric observations were performed at the Palomar 60-inch telescope and showed that the object has no detectable lightcurve (Trujillo and Brown, in prep.). Thermal emission observations at 1.2 mm wavelength were made using the Max-Planck Millimeter Bolometer (MAMBO) at the IRAM 30 m telescope on Pico Veleta (Spain). Pointing and ephemeris uncertainties were much less than the 10.6 arcsec beamwidth, and the weather conditions were good with zenith opacities less than ~0.2. Average sensitivity was 30 mJy s1/2, and the KBO was clearly detected with a statistical significance of ~4 sigmas. Our estimate for the diameter of the KBO is 886+115-131 km, which makes it slightly smaller than the largest main-belt asteroid 1 Ceres ( ~950 km). The red geometric albedo is estimated to be 0.101+0.038-0.022, more than twice the 4% value traditionally assumed for KBOs. Kuiper belt objects may display a wide variety of albedos, as their surfaces likely endure a combination of processes including radiation mantling and impact resurfacing. The values reported for 20000 Varuna are a diameter of 900+129-145 km and an albedo of 0.070+0.030-0.017 [1]. We note that both objects have relatively high inclinations ( ~ 20 degrees). Trujillo and Brown [2] reported a correlation between the inclination and color in the classical Kuiper belt, which possibly emphasizes the role of collisions in altering KBO surfaces. References [1] Jewitt, Aussel and Evans, Nature, 411, 2001. [2] Trujillo and Brown, ApJ Letters, 566, 2002.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #34
- Pub Date:
- September 2002
- Bibcode:
- 2002DPS....34.1703M