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42355 Typhon

Hubble Space Telescope image of Typhon and its moon Echidna, taken in 2006
Discovery
Discovered by	NEAT
Discovery date	5 February 2002
Designations
MPC designation	(42355) Typhon
Pronunciation	/ˈtaɪfɒn/
Named after	Τυφών Typhōn
Alternative designations	2002 CR46
Minor planet category	SDO Centaur
Adjectives	Typhonian /taɪˈfoʊniən/
Orbital characteristics
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 2
Observation arc	9563 days (26.18 yr)
Aphelion	58.982252 AU (8.8236193 Tm)
Perihelion	17.545721 AU (2.6248025 Tm)
Semi-major axis	38.263987 AU (5.7242110 Tm)
Eccentricity	0.5414560
Orbital period (sidereal)	236.70 yr (86453.7 d)
Mean anomaly	14.61898075°
Mean motion	0° 0 14.991 / day
Inclination	2.4252078°
Longitude of ascending node	351.9098598°
Argument of perihelion	159.3215723°
Known satellites	1 (Echidna)
TJupiter	4.692
Physical characteristics
Mean diameter	138±9 km 162±7 km
Mass	≈9.082×10 kg
Mean density	0.66+0.09 −0.08 g/cm
Synodic rotation period	9.67 h (0.403 d)
Geometric albedo	0.044±0.003 0.10±0.02
Spectral type	B−V=0.74±0.02 V−R=0.52±0.01
Absolute magnitude (H)	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, using an extended definition of a centaur as an object on a non-resonant (unstable) orbit with the perihelion inside the orbit of Neptune.

Physical properties

Typhon has a BR taxonomic class, with a blue surface. It has a resulting B–R magnitude of 1.274.

Based on a conventional magnitude-to-diameter conversion, the body measures 162 km in diameter, with an albedo of 0.044 and a magnitude of 7.5. Mike Brown gives it a diameter of 192 km with a magnitude of 7.5. Due to its small size, it is unlikely to be classified as a dwarf planet. As of 2021, no rotational lightcurve has been analyzed. The body's rotational period, pole, and actual shape remain unknown.

Moon

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.

External links

• 42355 Typhon at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

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• Scattered disc and detached objects
• Centaurs (small Solar System bodies)
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• Discoveries by NEAT
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