Romulus (moon)

Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#A0FFA0 | minorplanet=yes | width=28em
name=Romulus
discovery_ref = [http://cfa-www.harvard.edu/iauc/07500/07588.html IAUC 7588] , announcing the discovery of S/2001 (87) 1]
discoverer=Michael E. Brown and Jean-Luc Margot
discovered=February 18, 2001
mp_name=S/2001 (87) 1
mp_category=Main belt (Cybele)
orbit_ref=cite journal|author=F. Marchis et al|title="Discovery of the triple asteroidal system 87 Sylvia"|journal=Nature|volume=436|pages=822|year=2005|url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005Natur.436..822M&db_key=AST&data_type=HTML&format=&high=444b66a47d32268|doi=10.1038/nature04018]
semimajor= 1356 ± 5 km
eccentricity= 0.001 ± 0.001
period= 3.6496 ± 0.0007 d
avg_speed=27.0 m/s
inclination= 1.7 ± 1.0°
(with respect to Sylvia equator)
satellite_of = 87 Sylvia
dimensions= 18 ± 4 kmAssuming the same albedo as Sylvia]
mass= ~ 4e|15 kg "(estimate)"Assuming same density and albedo as Sylvia]
escape_velocity= ~ 7 m/s "(estimate)"
abs_magnitude= 10.7

Romulus is the outer and larger moon of the main belt asteroid 87 Sylvia, not to be confused with the directly Sun-orbiting asteroid 10386 Romulus. It follows an almost-circular close-to-equatorial orbit around the parent asteroid. In this respect it is similar to the other moon Remus.

Romulus was discovered in February 2001 from the Keck II telescope by Michael E. Brown and Jean-Luc Margot. Its full designation is (87) Sylvia I Romulus; before receiving its name, it was known as S/2001 (87) 1.The moon is named after Romulus, the mythological founder of Rome, one of the twins of Rhea Silvia raised by a wolf.

87 Sylvia has a low density, which indicates that it is likely a rubble pile asteroid formed when debris from a collision between its parent body and another asteroid re-accreted gravitationally. Therefore it is likely that both Romulus and Remus, the second of Sylvia's moons, are smaller rubble piles which accreted in orbit around the main body from debris of the same collision. In this case their albedo and density are expected to be similar to Sylvia's.

Romulus' orbit is expected to be quite stable − it lies far inside Sylvia's Hill sphere (about 1/50 of Sylvia's Hill radius), but also far outside the synchronous orbit.

From Romulus' surface, Sylvia takes up an angular region 16°×10° across, while Remus apparent size varies between 0.62° and 0.19°.

ee also

* Remus (moon)

References

External links

* [http://www.johnstonsarchive.net/astro/astmoons/am-00087.html Data on (87) Sylvia from Johnston's archive] (maintained by W. R. Johnston)
*" [http://www.eso.org/outreach/press-rel/pr-2005/pr-21-05.html Rubble-Pile Minor Planet Sylvia and Her Twins] " (ESO news release, August 2005) Includes images and artists impressions
*" [http://www.spacedaily.com/news/asteroid-01b.html Adaptive Optics System Reveals New Asteroidal Satellite] " (SpaceDaily.com, March 2001) Includes a discovery image.
* [http://cfa-www.harvard.edu/iauc/07500/07590.html IAUC 7590] , confirming the discovery of S/2001 (87) 1
* [http://cfa-www.harvard.edu/iauc/08500/08582.html IAUC 8582] , reporting discovery of S/2004 (87) 1 and naming Romulus and Remus