Light Curves of Dwarf Plutonian Planets and other Large Kuiper Belt Objects: Their Rotations, Phase Functions, and Absolute Magnitudes

Abstract

I report new time-resolved light curves and determine the rotations and phase functions of several large Kuiper Belt objects, which includes the dwarf planet Eris (2003 UB313). Three of the new sample of 10 trans-Neptunian objects display obvious short-term periodic light curves. (120348) 2004 TY364 shows a light curve which if double-peaked has a period of 11:70 � 0:01 hr and a peak-to-peak amplitude of 0:22 � 0:02 mag. (84922) 2003 VS2 has a well-defined double-peaked light curve of 7:41 � 0:02 hr with a range of 0:21 � 0:02 mag. (126154) 2001 YH140shows variability of 0:21 � 0: 04magwithapossib le13 :25 � 0:2hr single-peaked period. The seven new Kuiper Belt objects in the sample which show no discernible variations within the uncertainties on short rotational timescales are (148780) 2001 UQ18, (55565) 2002 AW197, (119979) 2002 WC19, (120132) 2003 FY128, (136108) Eris 2003 UB313, (90482) Orcus 2004 DW, and (90568) 2004 GV9 .F our of the 10 newly sampled Kuiper Belt objects were observed over a significant range of phase angles to determine their phase functions and absolute magnitudes. The three medium- to large-sized Kuiper Belt objects 2004 TY364, Orcus, and 2004 GV9 show fairly steep linear phase curves (� 0.18 to 0.26 mag deg � 1 ) between phase angles of 0.1 � and 1.5 � .T his is consistent with previous measurements obtained for moderately sized Kuiper Belt objects. The extremely large dwarf planet Eris (2003 UB313) shows a shallower phase curve (0:09 � 0:03 mag deg � 1 ) which is more similar to the other known dwarf planet Pluto.It appears that the surface properties of the largest dwarf planets inthe Kuiper Belt may be different than the smaller Kuiper Belt objects. This may have to do with the larger objects’ ability to hold more volatile ices, as well as sustain atmospheres. Finally, it is found that the absolute magnitudes obtained using the phase slopes found for individual objects are a few tenths of magnitudes different than that given by the Minor Planet Center.