Kuiper Belt object 2007 TY430 is the first wide , equal-sized , binary known in the 3:2 mean motion resonance with Neptune .
The two components have a maximum separation of about 1 arcsecond and are on average less than 0.1 magnitudes different in apparent magnitude with identical ultra-red colors ( g - i = 1.49 \pm 0.01 mags ) .
Using nearly monthly observations of 2007 TY430 from 2007-2011 , the orbit of the mutual components was found to have a period of 961.2 \pm 4.6 days with a semi-major axis of 21000 \pm 160 km and eccentricity of 0.1529 \pm 0.0028 .
The inclination with respect to the ecliptic is 15.68 \pm 0.22 degrees and extensive observations have allowed the mirror orbit to be eliminated as a possibility .
The total mass for the binary system was found to be 7.90 \pm 0.21 \times 10 ^ { 17 } kg .
Equal-sized , wide binaries and ultra-red colors are common in the low inclination “ cold ” classical part of the Kuiper Belt and likely formed through some sort of three body interactions within a much denser Kuiper Belt .
To date 2007 TY430 is the only ultra-red , equal-sized binary known outside of the classical Kuiper belt population .
Numerical simulations suggest 2007 TY430 is moderately unstable in the outer part of the 3:2 resonance and thus 2007 TY430 is likely an escaped “ cold ” classical object that later got trapped in the 3:2 resonance .
Similar to the known equal-sized , wide binaries in the cold classical population , the binary 2007 TY430 requires a high albedo and very low density structure to obtain the total mass found for the pair .
For a realistic minimum density of 0.5 g/cm ^ { 3 } the albedo of 2007 TY430 would be greater than 0.17 .
For reasonable densities , the radii of either component should be less than 60 km , and thus the relatively low eccentricity of the binary is interesting since no tides should be operating on the bodies at their large distances from each other .
The low prograde inclination of the binary also makes it unlikely the Kozai mechanism could have altered the orbit , making the 2007 TY430 binary orbit likely one of the few relatively unaltered primordial binary orbits known .
Under some binary formation models , the low inclination prograde orbit of the 2007 TY430 binary indicates formation within a relatively high velocity regime in the Kuiper Belt .