The Vesta family (adj. ''Vestian''; ) is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of asteroids. The cratering family is located in the inner

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...

in the vicinity of its namesake and principal body,

4 Vesta Vesta (minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, the ...

. It is one of the largest asteroid families with more than 15,000 known members and consists of mostly bright

V-type asteroid A V-type asteroid or Vestoid is an asteroid whose spectral type is that of 4 Vesta. Approximately 6% of main-belt asteroids are vestoids, with Vesta being by far the largest of them. They are relatively bright, and rather similar to the more common ...

s, so-called "vestoids".

Characteristics

The Vestian asteroids consist of

4 Vesta Vesta ( minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, t ...

, the second-most-massive of all asteroids (mean diameter of 530 km), and many small asteroids below 10 km diameter. The brightest of these, 1929 Kollaa and 2045 Peking, have an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...

of 12.2, which would give them a radius of about 7.5 km assuming the same high albedo as

4 Vesta Vesta ( minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, t ...

. The

originated from an impact on asteroid

4 Vesta Vesta ( minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, t ...

, with the giant south-polar crater the likely impact site. The family are thought to be the source of the HED meteorites. The Vesta family also includes a few J-type asteroids (related to the V-type), which are thought to have come from the deeper layers of Vesta's crust, and are similar to the

diogenite Diogenites are a group of the HED meteorite clan, a type of achondritic stony meteorites. Origin and composition Diogenites are currently believed to originate from deep within the crust of the asteroid 4 Vesta, and as such are part of the HED m ...

meteorites. A HCM numerical analysis (by Zappala 1995) determined a large group of 'core' family members, whose proper orbital elements lie in the approximate ranges: This gives the approximate boundaries of the family. At the present

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

, the range of osculating orbital elements of these core members is: The Zappala 1995 analysis found 235 core members. A search of a recent proper-element database
AstDys
for 96,944

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''mino ...

s in 2005 yielded 6,051 objects (about 6% of the total) lying within the Vesta-family region as per the first table above.

Interlopers

Spectroscopic analyses have shown that some of the largest Vestians are in fact interlopers. They are not of the V or J spectral class, but have similar orbital elements by coincidence. These include

306 Unitas Unitas ( minor planet designation: 306 Unitas) is a typical main belt asteroid that was discovered by Elia Millosevich on 1 March 1891 in Rome. The asteroid was named by the director of the Modena Observatory in honor of the Italian astronomer A ...

, 442 Eichsfeldia, 1697 Koskenniemi, 1781 Van Biesbroeck, 2024 McLaughlin, 2029 Binomi, 2086 Newell, 2346 Lilio, and others. (Identified by inspection of th
PDS asteroid taxonomy data set
.

References

* Zappalà, Vincenzo; Bendjoya, Philippe; Cellino, Alberto; Farinella, Paolo; and Froeschlé, Claude;
Asteroid Families: Search of a 12,487-Asteroid Sample Using Two Different Clustering Techniques
', Icarus, Volume 116, Issue 2 (August 1995), pages 291–314 * Bus, Schelte J.; and Binzel, Richard P.; ''Phase II of the Small Main-Belt Asteroid Spectroscopic Survey'', Icarus Vo.. 158, p. 106 (2002)
Data set online here

AstDys site
Proper elements for 96944 numbered minor planets. {{DEFAULTSORT:Vesta Family * Asteroid groups and families