 168P/Hergenrother during its 2012 outburst as imaged from theMount Lemmon Observatory | |
| Discovery[1] | |
|---|---|
| Discovered by | Carl W. Hergenrother |
| Discovery site | Catalina Sky Survey |
| Discovery date | 22 November 1998 |
| Designations | |
| P/1998 W2, P/2005 N2 | |
| Orbital characteristics[2][3] | |
| Epoch | 25 February 2023 (JD 2460000.5) |
| Observation arc | 21.12 years |
| Earliestprecovery date | 21 November 1998 |
| Number of observations | 3,631 |
| Aphelion | 5.817 AU |
| Perihelion | 1.357 AU |
| Semi-major axis | 3.587 AU |
| Eccentricity | 0.62169 |
| Orbital period | 6.794 years |
| Inclination | 21.615° |
| 355.43° | |
| Argument of periapsis | 15.041° |
| Mean anomaly | 188.01° |
| Last perihelion | 5 August 2019 |
| Next perihelion | 18 May 2026 |
| TJupiter | 2.663 |
| EarthMOID | 0.420 AU |
| JupiterMOID | 0.001 AU |
| Physical characteristics[2] | |
Mean diameter | 0.91 km (0.57 mi)[4] |
| Comet total magnitude (M1) | 7.0 |
| Comet nuclear magnitude (M2) | 15.2 |
| 8.0 (2012 apparition) | |
168P/Hergenrother is aperiodic comet in theSolar System. The comet, originally namedP/1998 W2, returned in 2005 and got the temporary nameP/2005 N2.[5] It was last observed in January 2020[3] and may have continued fragmenting after the 2012 outburst.
On 22 November 1998,Carl W. Hergenrother spotted a new comet fromCCD images taken byTimothy B. Spahr a day earlier with theCatalina Sky Survey's 0.41 m (16 in) telescope.[6] Preliminary orbital calculations byBrian G. Marsden reveal that the comet has a periodic orbit of 6.78 years.[1] At the time, the comet was a 17th-magnitude object within the constellationUrsa Minor.[a]
Between 2000 and 2002,Kazuo Kinoshita andShuichi Nakano independently used the comet's positions during its 1998 apparition to predict its next perihelion date, which is around 2 November 2005.[6] It was successfully recovered by Australian astronomer,David Herald, on 6 November 2005.[5]
The comet came toperihelion on 1 October 2012,[7] and was expected to reach aboutapparent magnitude 15.2, but due to an outburst the comet reached apparent magnitude 8.[8] As a result of the outburst of gas and dust, the comet was briefly more than 500 times brighter than it would have been without the outburst.[b] On 19 October, images by theVirtual Telescope Project showed a dust cloud trailing the nucleus.[9] Images by the 2 m (79 in)Faulkes Telescope North on 26 October,[10] confirm afragmentation event.[11] The secondary fragment was about magnitude 17. Further observations by the 8.1 m (320 in)Gemini telescope show that the comet fragmented into at least four parts in six fragmentation events.[10][12][13]
168P came to perihelion on 5 August 2019,[3] when it was 76 degrees from the Sun. It then made a closest approach to Earth on 6 November 2019, when it was 1 AU (150 million km) from Earth with asolar elongation of about 110 degrees. It was not recovered until 3 January 2020, when it was 141 degrees from the Sun, but only two observations on a single night were reported.
Observations conducted by theSpitzer Space Telescope between 2006 and 2007 showed that Hergenrother'snucleus was originally about 0.96 km (0.60 mi) in diameter before it fragmented on its 2012 outburst.[14] This was later revised to 0.91 km (0.57 mi) upon reanalysis of data in 2020.[4]
| Numbered comets | ||
|---|---|---|
| Previous 167P/CINEOS | 168P/Hergenrother | Next 169P/NEAT |
2019 in space | ||
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