42355 Typhon

42355 Typhon /ˈtfɒn/ 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.

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/ˈtfɒn/[1]
Named after
Τυφών Typhōn
2002 CR46
Scattered disc[2][3]

Centaur[4]

7:10 resonance
AdjectivesTyphonian /tˈfniən/[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)
Earth MOID16.557 AU (2.4769 Tm)
Jupiter MOID12.1588 AU (1.81893 Tm)
TJupiter4.692
Physical characteristics
Dimensions138±9 km[6]
162±7 km[7]
Mass≈9.082×1017 kg (calculated using a diameter of 138 km[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

    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] rarely Echidnean[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. "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. 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. 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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