42355 Typhon

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42355 Typhon
Hubble Space Telescope image of Typhon and its moon Echidna, taken in 2006
Discovery
Discovered byNEAT
Discovery date5 February 2002
Designations
Pronunciation/ˈtaɪfɒn/[1]
Named after
Τυφών Typhōn
2002 CR46
SDO[2][3]
Centaur[4]
AdjectivesTyphonian /taɪˈfoʊniən/[5]
Symbol (rare)
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
162±7 km[6]
Mass(9.49±0.52)×1017 kg[7]
Mean density
0.66+0.09
−0.08 g/cm3[8]
9.67 h (0.403 d)[8]
0.044±0.003[6]
Prominent water (H
2O/"bowl" type)[9]: 5 
B−R=1.29±0.07[6] V−I=0.99±0.04[7]
7.72±0.004[6]

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,[10] using an extended definition of a centaur as an object on a non-resonant (unstable) orbit with the perihelion inside the orbit of Neptune.[11]

Symbol

Planetary symbols are no longer much used in astronomy, so Typhon never received a symbol in the astronomical literature. There is no standard symbol for Typhon used by astrologers either. A hurricane symbol () has been used, which might be identified with U+1F300 🌀︎ CYCLONE (U+FE0E ︎ VARIATION SELECTOR-15 is used to make the character display as text).[12]

Physical properties

Measurements of its thermal radiation led to an equivalent diameter of about either 138±9 km or 185±7 km, with the latter value preferable.[8] The diameter of the central body (Typhon) is in the latter case 162±7 km.[6] Due to its small size, it is unlikely to be classified as a dwarf planet. As of 2021, no rotational lightcurve has been analyzed and the body's actual shape remain unknown.

Typhon has a BR taxonomic class, with a blue surface. It has a resulting B–R color difference of about 1.3,[6] while V–I color difference is about unity.[7] The spectra of Typhon show the presence of water ice and possibly of water altered silicates.[13]

Satellite

Echidna
Discovery
Discovery date2006
Designations
Pronunciation/ɪˈkɪdnə/[14]
Named after
Έχιδνα
AdjectivesEchidnian[15]
Echidnean (rarely)[16]
(both /ɪˈkɪdniən/)[17]
Orbital characteristics[18]
1580 km
Eccentricity0.507
18.982 d
Inclination42°
Satellite ofTyphon
Physical characteristics
Dimensions89±6 km

A large moon was identified in 2006.[7] It is named Echidna (formal designation (42355) Typhon I), after the monstrous mate of Typhon. It orbits Typhon at the distance of 1628±29 km, completing one orbit in 18.9709±0.0064 days. Its diameter is estimated at 89±6 km.[6] Echidna has the same color as Typhon.[7]

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. Santos-Sanz, P.; Lellouch, E.; Fornasier, S.; et al. (May 2012). ""TNOs are Cool": A survey of the trans-Neptunian region: IV. Size/albedo characterization of 15 scattered disk and detached objects observed with Herschel -PACS". Astronomy & Astrophysics. 541: A92. doi:10.1051/0004-6361/201118541.
  7. Grundy, W; Noll, K; Virtanen, J; Muinonen, K; Kern, S; Stephens, D; Stansberry, J; Levison, H; Spencer, J (September 2008). "(42355) Typhon–Echidna: Scheduling observations for binary orbit determination". Icarus. 197 (1): 260–268. doi:10.1016/j.icarus.2008.04.004.
  8. 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.
  9. Pinilla-Alonso, Noemí; Brunetto, Rosario; De Prá, Mário N.; Holler, Bryan J.; Hénault, Elsa; Feliciano, Ana Carolina de Souza; et al. (December 2024). "A JWST/DiSCo-TNOs portrait of the primordial Solar System through its trans-Neptunian objects" (PDF). Nature Astronomy. 9 (2): 230–244. Bibcode:2025NatAs...9..230P. doi:10.1038/s41550-024-02433-2. S2CID 274932942.
  10. 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.
  11. 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.
  12. Bala, Gavin Jared; Miller, Kirk (18 September 2023). "Unicode request for historical asteroid symbols" (PDF). unicode.org. Unicode. Retrieved 19 March 2025.
  13. Alvarez-Candal, A.; Barucci, M. A.; Merlin, F.; de Bergh, C.; Fornasier, S.; Guilbert, A.; Protopapa, S. (February 2010). "The trans-Neptunian object (42355) Typhon: composition and dynamical evolution". Astronomy and Astrophysics. 511: A35. doi:10.1051/0004-6361/200913102.
  14. "Echidna". Oxford English Dictionary (online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  15. François Hartog (Janet Lloyd, trans., 1988) The Mirror of Herodotus, p. 25
  16. J. A. Weinstock (2014) The Ashgate Encyclopedia of Literary and Cinematic Monsters, p. 79
  17. George Sandys (1669) Ovid's Metamorphosis Englished, 6th ed., p. 134.
  18. Wm. Robert Johnston (January 31, 2015). "Asteroids with Satellites Database--Johnston's Archive".