42355 Typhon
Hubble Space Telescope image of Typhon and its moon Echidna, taken in 2006
Discovery
Discovered byNEAT
Discovery date5 February 2002
Designations
(42355) Typhon
Pronunciation/ˈtaɪfɒn/[1]
Named after
Τυφών Typhōn
2002 CR46
SDO[2][3]
Centaur[4]
7:10 resonance
AdjectivesTyphonian /taɪˈfoʊniən/[5]
Orbital characteristics[2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 2
Observation arc9563 days (26.18 yr)
Aphelion58.982252 AU (8.8236193 Tm)
Perihelion17.545721 AU (2.6248025 Tm)
38.263987 AU (5.7242110 Tm)
Eccentricity0.5414560
236.70 yr (86453.7 d)
14.61898075°
0° 0m 14.991s / day
Inclination2.4252078°
351.9098598°
159.3215723°
Known satellites1 (Echidna)
TJupiter4.692
Physical characteristics
Mean diameter
138±9 km[6]
162±7 km[7]
Mass≈9.082×1017 kg[6]
Mean density
0.66+0.09
−0.08 g/cm3[6]
9.67 h (0.403 d)[6]
0.044±0.003[7]
0.10±0.02
B−V=0.74±0.02 V−R=0.52±0.01
7.5

42355 Typhon (/ˈtaɪfɒn/; provisional designation 2002 CR46) is a scattered disc object that was discovered on February 5, 2002, by the NEAT program. It measures 162±7 km in diameter, and is named after Typhon, a monster in Greek mythology.

Typhon is the first known binary centaur,[8] using an extended definition of a centaur as an object on a non-resonant (unstable) orbit with the perihelion inside the orbit of Neptune.[9]

Moon

Echidna
Discovery
Discovery date2006
Designations
(42355) Typhon I Echidna
Pronunciation/ɪˈkɪdnə/[10]
Named after
Έχιδνα
AdjectivesEchidnian[11]
Echidnean (rarely)[12]
(both /ɪˈkɪdniən/)[13]
Orbital characteristics
~1300 km
11 d
Satellite ofTyphon
Physical characteristics
Dimensions89±6 km

A large moon was identified in 2006. It is named Echidna (formal designation (42355) Typhon I Echidna), after the monstrous mate of Typhon. It orbits Typhon at ~1300 km, completing one orbit in about 11 days. Its diameter is estimated to be 89±6 km.

References

  1. ^ "Typhon". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  2. ^ a b "JPL Small-Body Database Browser: (42355 Typhon)" (2008-03-14 last obs). Retrieved 12 April 2016.
  3. ^ "List Of Centaurs and Scattered-Disk Objects". Minor Planet Center. Retrieved 2008-09-21.
  4. ^ (42355) Typhon and Echidna
  5. ^ "Typhonian". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  6. ^ a b c d Duffard, R.; Pinilla-Alonso, N.; Santos-Sanz, P.; Vilenius, E.; Ortiz, J. L.; Mueller, T.; et al. (April 2014). ""TNOs are Cool": A survey of the trans-Neptunian region. XI. A Herschel-PACS view of 16 Centaurs". Astronomy and Astrophysics. 564: 17. arXiv:1309.0946. Bibcode:2014A&A...564A..92D. doi:10.1051/0004-6361/201322377. S2CID 119177446.
  7. ^ a b 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
  8. ^ K. Noll; H. Levison; W. Grundy; D. Stephens (October 2006). "Discovery of a binary Centaur". Icarus. 184 (2): 611. arXiv:astro-ph/0605606. Bibcode:2006Icar..184..611N. doi:10.1016/j.icarus.2006.05.010. S2CID 18927838.
  9. ^ J. L. Elliot; S. D. Kern; K. B. Clancy; A. A. S. Gulbis; R. L. Millis; M. W. Buie; et al. (February 2005). "The Deep Ecliptic Survey: A Search for Kuiper Belt Objects and Centaurs. II. Dynamical Classification, the Kuiper Belt Plane, and the Core Population" (PDF). The Astronomical Journal. 129 (2): 1117. Bibcode:2005AJ....129.1117E. doi:10.1086/427395.
  10. ^ "Echidna". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  11. ^ François Hartog (Janet Lloyd, trans., 1988) The Mirror of Herodotus, p. 25
  12. ^ J. A. Weinstock (2014) The Ashgate Encyclopedia of Literary and Cinematic Monsters, p. 79
  13. ^ George Sandys (1669) Ovid's Metamorphosis Englished, 6th ed., p. 134.

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