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-type asteroid, which are also made up of stony irons and ordinary chondrites, with V-types containing more pyroxene than S-types.

A large proportion of vestoids have orbital elements similar to those of Vesta, either close enough to be part of the Vesta family, or having similar eccentricities and inclinations but with a semi-major axis lying between about 2.18 AU and the 3:1 Kirkwood gap at 2.50 AU. This suggests that most or all of them originated as fragments of Vesta's crust, possibly blasted out by a single very large impact at some point in its history. The enormous southern-hemisphere crater on Vesta, Rheasilvia, is the prime candidate for the impact site.^[1]

The electromagnetic spectrum has a very strong absorption feature longward of 0.75 μm, another feature around 1 μm and is very red shortwards of 0.7 µm. The visible wavelength spectrum of the V-type asteroids (including 4 Vesta itself) is similar to the spectra of basaltic achondrite HED meteorites.

A J-type has been suggested for asteroids having a particularly strong 1 μm absorption band similar to diogenite meteorites,^[2] likely being derived from deeper parts of the crust of 4 Vesta.

Distribution

The vast majority of V-type asteroids are members of the Vesta family along with Vesta itself. There are some Mars-crossers such as 9969 Braille, and some Near-Earth objects like 3908 Nyx.

There is also a scattered group of objects in the general vicinity of the Vesta family but not part of it. These include:^[3]

• 809 Lundia — Orbits within the Flora family region
• 956 Elisa
• 1459 Magnya — Orbits in the outer asteroid belt, too far from Vesta to be genetically related. May be the remains of a different ancient differentiated body that was shattered long ago.
• 2113 Ehrdni
• 2442 Corbett
• 2566 Kirghizia
• 2579 Spartacus — Contains a significant portion of olivine, which may indicate origin deeper within Vesta than other V-types.
• 2640 Hallstrom
• 2653 Principia
• 2704 Julian Loewe
• 2763 Jeans
• 2795 Lepage
• 2851 Harbin
• 2912 Lapalma
• 3849 Incidentia
• 3850 Peltier — Orbits within the Flora family region
• 3869 Norton
• 4188 Kitezh
• 4278 Harvey — Member of Baptistina family.
• 4434 Nikulin
• 4796 Lewis
• 4977 Rauthgundis
• 5379 Abehiroshi

See also

• Asteroid spectral types

References

1. S. J. Bus & R. P. Binzel (2002). "Phase II of the Small Main-belt Asteroid Spectroscopy Survey: A feature-based taxonomy". Icarus. 158: 146. Bibcode:2002Icar..158..146B. doi:10.1006/icar.2002.6856.
2. R. P. Binzel & S. Xu (1993). "Chips off of asteroid 4 Vesta: Evidence for the parent body of basaltic achondrite meteorites". Science. 260 (5105): 186–91. Bibcode:1993Sci...260..186B. doi:10.1126/science.260.5105.186. PMID 17807177.
3. V. Carruba; et al. (2005). "On the V-type asteroids outside the Vesta family". Astronomy & Astrophysics. 441 (2): 819. arXiv:astro-ph/0506656. Bibcode:2005A&A...441..819C. doi:10.1051/0004-6361:20053355.