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133P/Elst-Pizarro
From Wikipedia, the free encyclopedia
| Discovery | |
|---|---|
| Discovered by: | M. R. S. Hawkins and R. H. McNaught[1] and/or S. J. Bus [2] (as 1979 OW7) as well as Eric W. Elst and Guido Pizarro (as 1996 N2) |
| Discovery date: | 24 July 1979 (as 1979 OW7) [3] and 14 July 1996 (as 1996 N2) |
| Orbital characteristics | |
| Epoch 22 September 2006 (JD 2454000.5) | |
| Aphelion | 550.548 Gm (3.680 AU) |
| Perihelion: | 395.073 Gm (2.641 AU) |
| Semi-major axis: | 472.811 Gm (3.161 AU) |
| Eccentricity: | 0.1644 |
| Orbital period: | 2052.262 d (5.62 a) |
| Avg. orbital speed: | 16.64 km/s |
| Mean anomaly: | 310.762° |
| Inclination: | 1.386° |
| Longitude of ascending node: | 160.220° |
| Argument of perihelion: | 132.138° |
| Physical characteristics | |
| Rotation period: | 0.1446 d (3.471 h) [4] |
| Absolute magnitude: | 14 |
Comet Elst-Pizarro is a remarkable body in that it displays characteristics of both asteroids and comets [5], and is the prototype of main-belt comets. Its orbit keeps it within the asteroid main belt, while it displays a dust tail like a comet while near perihelion.
- As a comet it is formally designated 133P/Elst-Pizarro.
- As an asteroid it is designated 7968 Elst-Pizarro.
Elst-Pizarro was reported in 1979 as minor planet 1979 OW7, with its image on a photographic plate being completely stellar in appearance. The orbit remains entirely within the orbits of Mars and Jupiter, with eccentricity 0.165, typical of a minor planet in the asteroid belt. However, the images taken by Eric W. Elst and Guido Pizarro in 1996, when it was near perihelion, clearly show a cometary tail. Since this is not normal behaviour for asteroids, it is suspected that Elst-Pizarro has a different, probably icy, composition.
Subsequently, around the next perihelion in late 2002, the cometary activity appeared again, and persisted for several months [6].
At present, there are only four other objects that are cross-listed as both comets and asteroids: 2060 Chiron (95P/Chiron), Comet 107P/Wilson-Harrington (4015 Wilson-Harrington), 60558 Echeclus (174P/Echeclus), and 118401 LINEAR (176P/LINEAR (LINEAR 52)). 3200 Phaethon could be a member of this group [7].
- ^ MPEC 1996-R07
- ^ IAUC 6473
- ^ IAUC 6457
- ^ Planetary Data System (PDS) lightcurve data
- ^ Main-Belt Comets May Have Been Source Of Earths Water, Space Daily, Mar 23, (2006).
- ^ Main Belt Comets page by Henry Hsieh
- ^ The Geminid Meteor Shower (html). NASA (2004-12-06). Retrieved on 2007-11-08.
| Minor planets (see full list) |
||
|---|---|---|
| Previous minor planet | 7968 Elst-Pizarro | Next minor planet |
| Comets | ||
|---|---|---|
| Previous periodic comet | 133P/Elst-Pizarro | Next periodic comet |
| List of periodic comets | ||
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|---|
| Vulcanoids · Near-Earth asteroids · Main belt · Jupiter Trojans · Centaurs · Damocloids · Neptune Trojans · Comets · Trans-Neptunians (Kuiper belt • Scattered disc objects • Oort cloud) |
| For other objects and regions, see Asteroid groups and families, Binary asteroids, Asteroid moons, meteoroids and the Solar System. For a complete listing, see List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names. |