 Hubble image of C/1999 S4 disintegrating on 5 August 2000 | |
| Discovery[1] | |
|---|---|
| Discovered by | LINEAR (704) |
| Discovery site | Socorro, New Mexico |
| Discovery date | 27 September 1999 |
| Designations | |
| CJ99S040[1] | |
| Orbital characteristics[2][3] | |
| Epoch | 13 February 2000 (JD 2451587.5) |
| Observation arc | 300 days |
| Number of observations | 1,230 |
| Aphelion | ~1400 AU |
| Perihelion | 0.765 AU |
| Semi-major axis | ~700 AU |
| Eccentricity | 1.00010 |
| Orbital period | ~18,700 years |
| Inclination | 149.38° |
| 83.181° | |
| Argument of periapsis | 151.05° |
| Last perihelion | 26 July 2000 |
| EarthMOID | 0.174 AU |
| JupiterMOID | 0.802 AU |
| Physical characteristics[4][5] | |
| Dimensions | 0.9 km (0.56 mi) |
| Comet total magnitude (M1) | 9.6 |
| 6.6–6.8 (2000 apparition) | |
C/1999 S4 (LINEAR) was ahyperbolic comet discovered by theLincoln Near-Earth Asteroid Research survey on 27 September 1999.[1]
Itsnucleus was estimated to be about 0.9 km in diameter.[4] Before the comet broke up, the (dust and water) nucleus erosion rate was about 1 cm per day.[4] The comet brightened near 5 July 2000, and underwent a minorfragmentation event.[6] The comet brightened again around 20 July 2000, and then disintegrated.[7] The published optical and most radio data support that the main nuclear decay started 23 July 2000.[4] The dust cloud expanded at about 20 m/s (66 ft/s) while the fragments expanded at around 7 m/s (23 ft/s).[4] Other comets are known to have disappeared, but Comet LINEAR is the first one to have been caught in the act.[8]
The orbit of a long-period comet is properly obtained when theosculating orbit is computed at anepoch after leaving the planetary region and is calculated with respect to thecenter of mass of the Solar System. UsingJPL Horizons, the barycentric orbital elements for epoch 2010-Jan-01 generate asemi-major axis of 700 AU, an aphelion distance of 1400 AU, and a period of approximately 18,700 years.[2]
The comet made its closest approach to the Earth on 22 July 2000, at a distance of 0.372 AU (55.7 million km).[3] It came toperihelion on 26 July 2000, at a distance of 0.765 AU (114.4 million km) from the Sun.[3]
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