(26308) 1998 SM165
(26308) 1998 SM165, also written as (26308) 1998 SM165, is a binary trans-Neptunian object (TNO) that resides in the Kuiper belt. It was discovered on September 16, 1998, by Nichole Danzl. It is in a 1:2 orbital resonance with the planet Neptune.
Twotino
1998 SM165 has a semi-major axis (average distance from the Sun) near the edge of the classical belt. Both the Minor Planet Center (MPC) and the Deep Ecliptic Survey (DES) list this trans-Neptunian object as a twotino. For every one orbit that a twotino makes, Neptune orbits twice.
Physical characteristics
The observations with the infrared Spitzer Space Telescope combined with the orbits established using the Hubble Telescope allow the estimation of the density, assuming the components of equal albedo.
The resulting estimate of 7002510000000000000♠0.51+0.29
−0.14 g/cm3
is similar to the density of the binary plutino (47171) 1999 TC36 (0.3–0.8 g/cm3) and Saturn’s moon Hyperion (7002567000000000000♠0.567±0.102 g/cm3)
Such a low density is indicative of a highly porous composition dominated by ice.
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