42355 Typhon
Scattered disc object
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42355 Typhon (/ËtaɪfÉn/; 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,[9] using an extended definition of a centaur as an object on a non-resonant (unstable) orbit with the perihelion inside the orbit of Neptune.[10]
Hubble Space Telescope image of Typhon and its moon Echidna, taken in 2006 | |
| Discovery | |
|---|---|
| Discovered by | NEAT |
| Discovery date | 5 February 2002 |
| Designations | |
| (42355) Typhon | |
| Pronunciation | /ËtaɪfÉn/[1] |
Named after | Î¤Ï ÏÏν TyphÅn |
| 2002 CR46 | |
| SDO[2][3] Centaur[4] | |
| Adjectives | Typhonian /taɪËfoÊniÉn/[5] |
| Symbol | .svg){kind=small} (rare) |
| Orbital characteristics[2] | |
| 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) |
| 38.263987 AU (5.7242110 Tm) | |
| Eccentricity | 0.5414560 |
| 236.70 yr (86453.7 d) | |
| 14.61898075° | |
| 0° 0m 14.991s / day | |
| Inclination | 2.4252078° |
| 351.9098598° | |
| 159.3215723° | |
| Known satellites | 1 (Echidna) |
| TJupiter | 4.692 |
| Physical characteristics | |
| 162±7 km[6] | |
| Mass | (9.49±0.52)Ã1017 kg[7] |
Mean density | 0.66+0.09 â0.08 g/cm3[8] |
| 9.67 h (0.403 d)[8] | |
| 0.044±0.003[6] | |
| BâR=1.29±0.07[6] VâI=0.99±0.04[7] | |
| 7.72±0.004[6] | |
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 (.svg){kind=small}
) has been used, which might be identified with U+1F300 ðï¸ CYCLONE (U+FE0E ï¸ VARIATION SELECTOR-15 is used to make the character display as text).[11]
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 BâR color difference of about 1.3,[6] while VâI color difference is about unity.[7] The spectra of Typhon show the presence of water ice and possibly of water altered silicates.[12]
Satellite
| Discovery | |
|---|---|
| Discovery date | 2006 |
| Designations | |
| (42355) Typhon I | |
| Pronunciation | /ɪËkɪdnÉ/[13] |
Named after | ÎÏιδνα |
| Adjectives | Echidnian[14] Echidnean (rarely)[15] (both /ɪËkɪdniÉn/)[16] |
| Orbital characteristics | |
| ~1300 km | |
| 11 d | |
| Satellite of | Typhon |
| Physical characteristics | |
| Dimensions | 89±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]