37th DPS Meeting, 4-9 September 2005
Session 56 TNOs and Centaurs
Poster, Thursday, September 8, 2005, 6:00-7:15pm, Music Recital Room

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[56.16] The High Fraction of Binaries in the Cold Classical Kuiper Belt

D.C. Stephens (JHU), K.S. Noll (STScI)

We have analyzed a homogeneous set of observations of 81 transneptunian objects (TNOs) obtained with the NIC2 camera on the Hubble Space Telescope with the goal of identifying partially resolved binaries. Using single and binary PSF-fitting and comparing the \Delta\chi2 value of the two fits, we have identified at a >3\sigma confidence level 6 unresolved binaries in addition to the 3 binaries previously found in this data set. With the identification of these binaries, we find that 11+5-2% of transneptunian objects are binaries at the separation and brightness limits of the NIC2 camera. We note that 6 of these 9 binaries are cold classicals (i < 5 deg), and find a binary fraction of 23+10-6% for these objects. The other 3 binaries are scattered disk objects, and when we combine the scattered disk, resonant and hot classical populations, we find a binary fraction amid the dynamically excited TNOs of 6+4-2%. Thus binaries appear to be nearly four times more common in the cold classical belt than in the dynamically excited populations.

This research has been supported by program 9386, funded through a grant to STScI, operated by AURA under NASA contract NAS 5-26555.

The author(s) of this abstract have provided an email address for comments about the abstract: stephens@pha.jhu.edu

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.