65489 Ceto

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Ceto
65489 Ceto.tiff
Orbit (top view)
Discovery
Discovered by C. A. Trujillo and M. Brown
Discovery site Palomar
Discovery date March 22, 2003
Designations
MPC designation 65489
Named after
Ceto
2003 FX128
TNO
Centaur–extended[1]
Adjectives Cetoean
Orbital characteristics[4]
Epoch 2455200.5 (2010-Jan-04.0)
Aphelion 181.90 AU
Perihelion 17.8125 AU
99.86 AU
Eccentricity 0.8216
998 years
7.384°
Inclination 22.3229°
172.0572°
319.594°
Known satellites Phorcys
(171±10[2] ~ 132+6
−14
 km
[3] in diameter)
Physical characteristics
Dimensions 223±10 km[2]
174+16
−18
 km
[3]
Mass (5.4±0.4)×1018 kg (system)[3]
Mean density
1.37 g/cm3 (system)[3]
Equatorial surface gravity
3.3 cm/s2[3]
0.056±0.006[2]
0.084±0.02[3]
6.54±0.06[2]

65489 Ceto /ˈst/ is a binary trans-Neptunian object (TNO) discovered on March 22, 2003 by C. A. Trujillo and M. Brown at Palomar. It is named after the sea goddess Ceto from Greek mythology. The object was identified as a binary on April 11, 2006 by K. Noll, H. Levison, W. Grundy and D. Stephens using the Hubble Space Telescope; the companion object is named Phorcys (/ˈfɔərss/, formally (65849) Ceto I Phorcys), after the Greek sea god. Using an extended definition of a centaur as an object on a non-resonant (unstable) orbit with its perihelion inside the orbit of Neptune,[5] the Ceto system can be considered the second known binary centaur.[3] It came to perihelion in 1989.[4]

Physical characteristics

65489 Ceto is an example of a close binary TNO system in which the components are of similar size. Combined observations with the infrared Spitzer Space Telescope and the Hubble Telescope allow the diameter of Ceto itself to be estimated at 174+16
−18
 km
and the diameter of Phorcys at 132+6
−14
 km
, assuming equal albedo for both components.[3]

The binary nature of Ceto enables direct calculation of the system mass, allowing estimation of the masses of the components and providing additional constraints on their composition. The estimated density of Ceto is 1.37+0.66
−0.32
 g/cm3
, significantly less than that of the large TNOs (Haumea: 3.0 g/cm3, Eris: 2.26, Pluto: 2.03, Charon: 1.65) but significantly more than that of smaller TNOs (e.g. 0.7 g/cm3 for (26308) 1998 SM165). Phorcys has a mass of about 1.67×1018 kg.[3] Unless the bodies are porous, the density is consistent with rock–ice composition, with rock content around 50%.[3]

It has been suggested that tidal forces, together with other potential heat sources (e.g. collisions or 26Al decay) might have raised the temperature sufficiently to crystallise amorphous ice and reduce the void space inside the object. The same tidal forces could be responsible for the quasi-circular orbits of the components of Ceto.[3]

Michael Brown's website lists it as possibly a dwarf planet.[6]

See also

References

  1. Lua error in package.lua at line 80: module 'strict' not found.
  2. 2.0 2.1 2.2 2.3 Santos-Sanz, P., Lellouch, E., Fornasier, S., Kiss, C., Pal, A., Müller, T. G., Vilenius, E., Stansberry, J., Mommert, M., Delsanti, A., Mueller, M., Peixinho, N., Henry, F., Ortiz, J. L., Thirouin, A., Protopapa, S., Duffard, R., Szalai, N., Lim, T., Ejeta, C., Hartogh, P., Harris, A. W., & Rengel, M. (2012). “TNOs are Cool”: A Survey of the Transneptunian Region IV - Size/albedo characterization of 15 scattered disk and detached objects observed with Herschel Space Observatory-PACS
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 Lua error in package.lua at line 80: module 'strict' not found.
  4. 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
  5. Lua error in package.lua at line 80: module 'strict' not found.
  6. Lua error in package.lua at line 80: module 'strict' not found.

External links