Remus, formal designation 87 Sylvia II, is the inner and smaller moon of the

main-belt asteroid The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...

87 Sylvia 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 ...

. It follows an almost-circular and close-to-equatorial orbit around the parent asteroid. In this respect it is similar to the other Sylvian moon

Romulus Romulus (, ) was the legendary founder and first king of Rome. Various traditions attribute the establishment of many of Rome's oldest legal, political, religious, and social institutions to Romulus and his contemporaries. Although many of th ...

Discovery and naming

Remus was discovered several years after Romulus on images taken starting on August 9, 2004, and announced on August 10, 2005. It was discovered by

Franck Marchis Franck Marchis (born April 6, 1973 in Caen, France), astronomer and planetary scientist, is best known for his discovery and characterization of multiple asteroids, his study of Io volcanism and imaging of exoplanets, planets around other star ...

UC Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a public land-grant research university in Berkeley, California, United States. Founded in 1868 and named after the Anglo-Irish philosopher George Berkele ...

, and

Pascal Descamps Pascal, Pascal's or PASCAL may refer to: People and fictional characters * Pascal (given name), including a list of people with the name * Pascal (surname), including a list of people and fictional characters with the name ** Blaise Pascal, Frenc ...

Daniel Hestroffer Daniel commonly refers to: * Daniel (given name), a masculine given name and a surname * List of people named Daniel * List of people with surname Daniel * Daniel (biblical figure) * Book of Daniel, a biblical apocalypse, "an account of the acti ...

, and

Jérôme Berthier Jerome (c.347–420) was a priest, confessor, theologian and historian from Dalmatia. Jerome may also refer to: People Given name * Jerome (given name), a masculine name of Greek origin, with a list of people so named * Saint Jerome (disambiguat ...

of the

Observatoire de Paris The Paris Observatory (, ), a research institution of the Paris Sciences et Lettres University, is the foremost astronomical observatory of France, and one of the largest astronomical centres in the world. Its historic building is on the Left Ban ...

, France, using the Yepun telescope of the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 m ...

(ESO) in

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. Marchis, the project leader, was waiting for the completion of the image acquisition programme before starting to process the data. Just as he was set to go on vacation in March 2005, Descamps sent him a brief note entitled "87 Sylvia est triple ?" pointing out that he could see two moonlets on several images of Sylvia. The entire team then focused quickly on analysis of the data, wrote a paper, submitted an abstract to the August meeting in Rio de Janeiro and submitted a naming proposal to the IAU. Its formal designation is (87) Sylvia II; before receiving its name, it was known as S/2004 (87) 1. The moon is named after Remus, twin of the mythological founder of

Rome Rome (Italian language, Italian and , ) is the capital city and most populated (municipality) of Italy. It is also the administrative centre of the Lazio Regions of Italy, region and of the Metropolitan City of Rome. A special named with 2, ...

, one of the children of

Rhea Silvia Rhea (or Rea) Silvia (), also known as Ilia, (as well as other names) was the mythical mother of the twins Romulus and Remus, who founded the city of Rome.Livy I.4.2 This event was portrayed numerous times in Roman art. Her story is told in the ...

raised by a wolf.

Characteristics

87 Sylvia has a low density, which indicates that it is probably a

rubble pile In astronomy, a rubble pile is a celestial body that consists of numerous pieces of debris that have coalesced under the influence of gravity. Rubble piles have low density because there are large cavities between the various chunks that make the ...

asteroid formed when debris from a collision between its parent body and another asteroid re-accreted gravitationally. Thus it is likely that both Remus and Romulus 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. Remus's orbit is expected to be quite stable: it lies far inside Sylvia's

Hill sphere The Hill sphere is a common model for the calculation of a Sphere of influence (astrodynamics), gravitational sphere of influence. It is the most commonly used model to calculate the spatial extent of gravitational influence of an astronomical ...

(about 1/100 of Sylvia's

Hill radius A hill is a landform that extends above the surrounding terrain. It often has a distinct summit, and is usually applied to peaks which are above elevation compared to the relative landmass, though not as prominent as mountains. Hills fall unde ...

), but also far outside the

synchronous orbit A synchronous orbit is an orbit in which an orbiting body (usually a satellite) has a period equal to the average rotational period of the body being orbited (usually a planet), and in the same direction of rotation as that body. Simplified meani ...

. From Remus's surface, Sylvia appears huge, taking up an angular region roughly 30°×18° across, while Romulus's apparent size varies between 1.6° and 0.5° across.

Notes

References

External links

Data on (87) Sylvia from Johnston's archive
(maintained by W. R. Johnston) *

'' (ESO news release, August 2005) Includes images and artists impressions

reporting discovery of S/2004 (87) 1 and naming Romulus and Remus {{Small Solar System bodies Asteroid satellites 87 Sylvia 20040809

Discovery and naming

Characteristics

See also

Notes

References

External links