V-type asteroid

The spectra of the V-type asteroids, or vestoids, are similar to that of 4 Vesta, by far the largest asteroid in this class (hence the name). Approximately 6% of main-belt asteroids are vestoids.

A large proportion have orbital elements similar to those of 4 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 V-type asteroids are moderately bright, and rather similar to the more common S-type, which are also made up of stony irons and ordinary chondrites. This rather rare type of asteroid contains more pyroxene than the S-type.

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]

See also

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.
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