87 Sylvia
|
|
| Discovery A (http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html) | |
|---|---|
| Discoverer | Norman Robert Pogson |
| Discovery date | May 16, 1866 |
| Alternate designations | A909 GA B (http://cfa-www.harvard.edu/iau/MPDes.html) |
| Category | Main belt (Cybele) |
| Orbital elements C (http://asteroid.lowell.edu/) Epoch July 14, 2004 (JD 2453200.5) | |
| Eccentricity (e) | 0.080 |
| Semi-major axis (a) | 522.137 Gm (3.490 AU) |
| Perihelion (q) | 480.594 Gm (3.213 AU) |
| Aphelion (Q) | 563.679 Gm (3.768 AU) |
| Orbital period (P) | 2381.697 d (6.52 a) |
| Mean orbital speed | 15.94 km/s |
| Inclination (i) | 10.855° |
| Longitude of the ascending node (Ω) | 73.342° |
| Argument of perihelion (ω) | 266.195° |
| Mean anomaly (M) | 352.763° |
| Physical characteristics | |
| Dimensions | 260.9 km |
| Mass | 1.9×1019 kg |
| Density | 2.0 g/cm³ |
| Surface gravity | 0.0729 m/s² |
| Escape velocity | 0.1379 km/s |
| Rotation period | 0.216 d 1 (http://www.astrosurf.com/aude-old/map_files/AstVarMAP01-2003.htm) |
| Spectral class | X (Bus & Binzel, 2002) |
| Absolute magnitude | 6.94 |
| Albedo | 0.0435 2 (http://www.psi.edu/pds/archive/astdata/ALBEDOS/albedos.tab) |
| Mean surface temperature | ~151 K |
87 Sylvia (sil'-vee-a) is one of the largest main belt asteroids. It is very dark in color and has probably very primitive composition. It orbits beyond most of the main belt asteroids, so it was classed as one of the Cybeles (See Minor planet groups).
Sylvia was discovered by N. R. Pogson on May 16, 1866 from Madras (Chennai), India. The reason for its name remains uncertain. In the article (MNRAS, 1866) annoncing the discovery of this asteroid, Pogson explained that he selected the name in reference to Rhea Silvia, mother of Romulus and Remus. It has been claimed that it honours the first wife of astronomer Camille Flammarion, but there is no strong evidence for this.
A companion of Sylvia was discovered on February 18, 2001 from the Keck II telescope by Michael E. Brown and Jean-Luc Margot. It is 15 km in diameter and orbits at distance of 1370 km. No official name has been assigned to the satellite yet. [1] (http://cfa-www.harvard.edu/iauc/07500/07588.html)
The discovery of the satellite made possible an accurate measurement of the mass and density of Sylvia. Its density was found to be very low, indicating that the asteroid is probably very porous.
External links
- Data on (87) Sylvia from Johnston's archive (http://www.johnstonsarchive.net/astro/astmoons/am-00087.html)
- Adaptive Optics System Reveals New Asteroidal Satellite (http://www.spacedaily.com/news/asteroid-01b.html) (SpaceDaily.com)
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