238P/Read (P/2005 U1) is a main-belt comet[1][2] discovered on 24 October 2005 by astronomer Michael T. Read using the Spacewatch 36-inch telescope on Kitt Peak National Observatory. It has an orbit within the asteroid belt and has displayed the coma of a traditional comet. It fits the definition of an Encke-type comet with (TJupiter > 3; a < aJupiter).[3]
Discovery | |||||||||
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Discovered by | Michael T. Read (Spacewatch) | ||||||||
Discovery date | 24 October 2005 | ||||||||
Designations | |||||||||
Minor planet category | Main-belt comet [1][2] Encke-type comet [3] | ||||||||
Orbital characteristics[3] | |||||||||
Epoch 7 January 2006 | |||||||||
Uncertainty parameter 1 | |||||||||
Aphelion | 3.9645 AU (Q) | ||||||||
Perihelion | 2.3647 AU (q) | ||||||||
Semi-major axis | 3.1646 AU (a) | ||||||||
Eccentricity | 0.25277 | ||||||||
Orbital period (sidereal) | 5.63 yr | ||||||||
Mean anomaly | 28.566° (M) | ||||||||
Inclination | 1.2662° | ||||||||
Longitude of ascending node | 51.647° | ||||||||
Time of perihelion | 2022-Jun-05[4] | ||||||||
Argument of perihelion | 325.76° | ||||||||
TJupiter | 3.153 | ||||||||
Physical characteristics | |||||||||
Mean diameter | 0.6 km (approx.)[5] | ||||||||
Mean density | 1.0 g/cm3 (assumed)[5] | ||||||||
Albedo | 0.04 (assumed)[5] | ||||||||
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Apparent magnitude | 19.62 to 23.41 | ||||||||
Absolute magnitude (H) | 20.1±0.4R[5] | ||||||||
Before it was discovered 238P came to perihelion on 2005 July 27.[3] When it was discovered on 2005 October 24, it showed vigorous cometary activity until 2005 December 27.[5] Outgassing likely began at least 2 months before discovery.[5] The activity of 238P is much stronger than 133P/Elst-Pizarro and 176P/LINEAR.[5] This may indicate that the impact assumed to have triggered 238P's activity occurred very recently.[5]
Observations of 238P when it was inactive in 2007 suggests that it has a small nucleus only about 0.6 km in diameter.[5]
It came to perihelion on 2011 March 10[5] and 2016 October 22.[6][4] It will next come to perihelion on 2022 June 5.[4]
238P/Read was the target of a mission proposal in NASA's Discovery Program in the 2010s called Proteus, however it was not selected for further development.[7] Discovery program's founding mission was to an asteroid, but it went to a Near-Earth asteroid.[8] A mission to a main-belt asteroid was proposed in the 1990s (also see Deep Impact (spacecraft)).[9]
Numbered comets | ||
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Previous 237P/LINEAR |
238P/Read | Next 239P/LINEAR |