- 7968 Elst–Pizarro
-
7968 Elst–Pizarro
133P/Elst–PizarroDiscoveryDiscovered 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) DesignationsAlternate name(s) P/1996 N2, 1979 OW7 Minor planet
categoryMain-belt comet[4][5]
Main-belt asteroid[6]
Themis/Beagle family[4]Epoch 23 July 2010 (JD 2455400.5)
T_jup = 3.184Aphelion 3.6729 AU (Q)
(549.45 Gm)Perihelion 2.6462 AU (q)
(395.86 Gm)Semi-major axis 3.1596 AU (a)
(472.66 Gm)Eccentricity 0.16246 Orbital period 5.62 yr
(2051.3 d)Average orbital speed 16.64 km/s Mean anomaly 196.46° Inclination 1.3863° Longitude of ascending node 160.15° Argument of perihelion 132.29° Physical characteristicsDimensions 3.8±0.6 km (Spitzer)[7] Mean density 1.3(?) g/cm³[8] Rotation period 3.471 hr
(0.1446 d)[6]Albedo 0.05±0.02R[7] Temperature 160K[8] Apparent magnitude 17.24 to 20.71 Absolute magnitude (H) 14.0[6]
15.3R (2004)[8]
15.49R (2010)[9]Comet Elst–Pizarro is a body that displays characteristics of both asteroids and comets,[10] and is the prototype of main-belt comets. Its orbit keeps it within the asteroid belt, yet it displayed a dust tail like a comet while near perihelion in 1996, 2001, and 2007.
- 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. The cometary nature of Elst–Pizarro was first discovered on 1996 August 7 when a linear dust feature was observed.[8]
Subsequently, around the next perihelion in November 2001, the cometary activity appeared again, and persisted for 5 months.[8]
At present, there are only four other objects that are cross-listed as both comets and asteroids: 2060 Chiron (95P/Chiron), 4015 Wilson-Harrington (107P/Wilson-Harrington), 60558 Echeclus (174P/Echeclus), and 118401 LINEAR (176P/LINEAR, previously 1999 RE70).[11] As a dual status object, astrometric observations of 7968 Elst–Pizarro should be reported under the minor planet designation.[11]
It will come to perihelion on 8 February 2013.[6]
References
- ^ MPEC 1996-R07
- ^ IAUC 6473
- ^ IAUC 6457
- ^ a b Henry H. Hsieh (May 2010). "Main Belt Comets". Hawaii. http://www.ifa.hawaii.edu/~hsieh/mbcs.shtml. Retrieved 2010-12-15. (older 2010 site)
- ^ David Jewitt. "Main Belt Comets". UCLA, Department of Earth and Space Sciences. http://www2.ess.ucla.edu/~jewitt/mbc.html. Retrieved 2010-12-15.
- ^ a b c d e "JPL Small-Body Database Browser: 7968 Elst–Pizarro (1996 N2)". 2008-11-20 last obs. http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=133P. Retrieved 2012-12-12.
- ^ a b Hsieh, Henry H.; Jewitt, David C.;Fernández, Yanga R. (2009). "Albedos of Main-Belt Comets 133P/Elst–Pizarro and 176P/LINEAR". The Astrophysical Journal Letters 694 (2): L111–L114. arXiv:0902.3682. Bibcode 2009ApJ...694L.111H. doi:10.1088/0004-637X/694/2/L111.
- ^ a b c d e Hsieh, Henry H.; Jewitt, David C.;Fernández, Yanga R. (2004). "The Strange Case of 133P/Elst–Pizzarro: A Comet Among the Asteroids". The Astronomical Journal 127 (5): 2997–3017. Bibcode 2004AJ....127.2997H. doi:10.1086/383208.
- ^ Hsieh, Henry H.; Jewitt, David C.;Lacerda, Pedro; Lowry, Stephen C.; Snodgrass, Colin (2010). "The return of activity in main-belt comet 133P/Elst–Pizarro". Monthly Notices of the Royal Astronomical Society 403 (1): 363–377. arXiv:0911.5522. Bibcode 2010MNRAS.403..363H. doi:10.1111/j.1365-2966.2009.16120.x.
- ^ Main-Belt Comets May Have Been Source Of Earths Water, Space Daily, Mar 23, (2006).
- ^ a b "Dual-Status Objects". Minor Planet Center. 2008-03-06. http://www.minorplanetcenter.org/iau/lists/DualStatus.html. Retrieved 2010-12-17.
Minor planets navigator Periodic comets (by number) Previous
132P/Helin-Roman-Alu7968 Elst–Pizarro Next
134P/Kowal-VávrováSmall Solar System bodies Minor planets - Designation
- Groups
- Moons
- Meanings of names
- Pronunciation of names
Comets Meteoroids Lists / categories - Asteroid groups and families
- Asteroid moons
- Binary asteroids
- Minor planets
Categories:- Comets
- Main Belt asteroids
- Themistian asteroids
- Asteroids named for people
- Main Belt comets
- Astronomical objects discovered in 1996
Wikimedia Foundation. 2010.
