87 Sylvia is one of the largest asteroids (approximately tied for 7th place, to within measurement uncertainties). It is the parent body of the Sylvia family and member of Cybele group located beyond the main asteroid belt (see minor-planet groups). Sylvia was the first asteroid known to possess more than one moon.

Discovery and naming

Sylvia was discovered by N. R. Pogson on 16 May 1866, from Madras (Chennai), India. Antonio Paluzie-Borrell, writing in Paul Herget's The Names of the Minor Planets (1955), mistakenly states that the name honors Sylvie Petiaux-Hugo Flammarion, the first wife of astronomer Camille Flammarion. In fact, in the article announcing the discovery of the asteroid, Pogson explained that he selected the name in reference to Rhea Silvia, mother of Romulus and Remus (MNRAS, 1866).

Physical characteristics

Sylvia is very dark in color and probably has a primitive composition, though with some internal differentiation. The discovery of its moons made possible an accurate measurement of the asteroid's mass, density and mass distribution. Its density is low (around 1.4 times the density of water), indicating that the asteroid is porous; best-fit models estimate it had an original composition by volume of 35% rock, 13% ice and 52% internal voids, and that today it consists of a pristine anhydrous outer layer, and a differentiated interior, with meltwater having percolated inward so that the porosity of the rock is filled with ice out to a radius of about 46 km, then ice-free porous rock out to about 104 km. || || || ||

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See also

  • List of exceptional asteroids

Notes

References

  • Pogson, N. R. (1866), Minor Planet (87) Sylvia, Monthly Notices of the Royal Astronomical Society, Vol. 26, p. 311 (June 1866)
  • Data on (87) Sylvia from Johnston's archive (maintained by W. R. Johnston)
  • Rubble-Pile Minor Planet Sylvia and Her Twins (ESO news release, August 2005) Includes images and artists impressions
  • Adaptive Optics System Reveals New Asteroidal Satellite (SpaceDaily.com, March 2001) Includes a discovery image.
  • Space.com: First asteroid trio discovered
  • IAUC 7588, reporting discovery of S/2001 (87) 1
  • IAUC 7590, confirming the discovery
  • IAUC 8582, reporting discovery of S/2004 (87) 1 and naming Romulus and Remus
  • An animation of (87) Sylvia and its moons (on Vimeo)
  • Shape model derived from lightcurve (on page 19)
  • Instability zones for satellites of asteroids. The example of the (87) Sylvia system (arXiv:1112.5363 / 22 December 2011)
  • Orbits, masses, and evolution of main belt triple (87) Sylvia (arXiv:1206.5755 / 25 June 2012)
  • Occultation of TYC 1856-00745-1 by (87) Sylvia and by its satellite Romulus (E. Frappa, A. Klotz, P. Dubreuil)