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S. S. Sheppard, D. C. Jewitt (Univ. of Hawaii)
We have enlarged our sample (Sheppard and Jewitt 2002) of bright Trans-Neptunian objects which have been systematically monitored for possible light variations due to rotational and phase angle effects. Most objects have voluminous observations with the University of Hawaii 2.2 meter telescope on consecutive nights as well as at significantly different phase angles. We find that 9 of 33 (27%) objects in our sample show peak-to-peak amplitudes >0.15 magnitudes while 15% have amplitudes >0.4 magnitudes and 9% have amplitudes >0.6 magnitudes. In addition, we find that the lightcurve of 1995 SM55 may be variable. Comparing the main-belt asteroids of similar size to the Kuiper Belt objects in our sample (24 asteroids have diameters greater than 200 km) shows the asteroids have a larger fraction with amplitudes >0.15 magnitudes, a comparable fraction with amplitudes >0.4 magnitudes but a smaller fraction with amplitudes >0.6 magnitudes. We also continue to find the phase functions of the Trans-Neptunian objects to be very steep and linear with a median slope of 0.16 magnitudes per degree in the phase angle range 0 to 2 degrees. This is significantly different than the very shallow phase function of the high albedo Pluto. We will discuss our new results as they relate to the possible shapes, limiting densities and surface characteristics of Trans-Neptunian objects.
Reference Sheppard, S. and Jewitt, D (2002). Astron. J., 124, 1757-1775.
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The author(s) of this abstract have provided an email address for comments about the abstract: sheppard@ifa.hawaii.edu
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.