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Post Info TOPIC: KBO (139775) 2001 QG298
Blobrana


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RE: KBO (139775) 2001 QG298
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Spinning hourglass object may be the first of many to be discovered in the Kuiper belt

The bizarre, hourglass-shaped Kuiper belt object 2001QG298 spins round like a propeller as it orbits the Sun, according to an astronomer from Queens University Belfast.   The discovery that the spinning object is tilted at nearly 90 degrees to the ecliptic plane is surprising, and suggests that this type of object could be very common in the Kuiper belt. The finding will be presented by Dr Pedro Lacerda at the Joint Meeting of the European Planetary Science Congress and the Division for Planetary Sciences in Nantes, France, on 3 October 2011.
The Kuiper belt objects (KBOs) orbit the sun beyond Neptune and are the best preserved leftovers of the formation of the planets. 2001QG298 is a remarkable KBO made up from two components that orbit each other very closely, possibly touching. 
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Blobrana


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Title: A Change in the Lightcurve of Kuiper Belt Contact Binary (139775) 2001 QG298
Authors: Pedro Lacerda

New observations show that the lightcurve of Kuiper belt contact binary (139775) 2001 QG298 has changed substantially since the first observations in 2003. The 2010 lightcurve has a peak-to-peak photometric of range \Deltam{2010}=0.7±0.1 mag, significantly lower than in 2003, \Deltam{2003}=1.14±0.04 mag. This change is most simply interpreted if 2001 QG298 has an obliquity near 90 deg. The observed decrease in \Deltam is caused by a change in viewing geometry, from equator-on in 2003 to nearly 16 deg (the orbital angular distance covered by the object between the observations) off the equator in 2010. The 2003 and 2010 lightcurves have the same rotation period and appear in phase when shifted by an integer number of full rotations, also consistent with high obliquity. Based on the new 2010 lightcurve data, we find that 2001 QG298 has an obliquity \epsilon=90±30 deg. Current estimates of the intrinsic fraction of contact binaries in the Kuiper belt are debiased assuming that these objects have randomly oriented spins. If, as 2001 QG298, KBO contact binaries tend to have large obliquities, a larger correction is required. As a result, the abundance of contact binaries may be larger than previously believed.

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