Remus (moon)
| (87) Sylvia II (Remus) | |
|---|---|
|
|
| Asteroid Sylvia with Romulus and Remus | |
| Provisional or systematic name | S / 2004 (87) 1 |
| Central body | (87) Sylvia |
| Properties of the orbit | |
| Major semi-axis | 701.64 ± 0.02 km |
| Periapsis | 636.39 km |
| Apoapsis | 766.89 km |
| eccentricity | 0.093 ± 0.021 |
| Orbit inclination | 2.0 ± 1.0 ° |
| Orbital time | 1.373 ± 0.01 d |
| Mean orbital velocity | 0.0372 km / s |
| Physical Properties | |
| Apparent brightness | 11.1 mag |
| Medium diameter | 10.6 ± 1.6 km |
| Dimensions | 9.32 + 20.7 / -8.3 · 10 14 kg |
| Medium density | ≈ (1.2 ± 0.1) g / cm 3 |
| Acceleration of gravity on the surface | ≈ 0 m / s 2 |
| Escape speed | ≈ 0 m / s |
| discovery | |
| Explorer |
|
| Date of discovery | August 9, 2004 |
| Remarks | With the discovery of Remus, a first triple asteroid system was known. |
Remus is the inner and smaller of the two moons of the main belt asteroid (87) Sylvia ( Cybele Group ). Its mean diameter is around 11 kilometers, which corresponds to about 1/24 of the Sylvia diameter.
Discovery and naming
Remus was discovered on August 9, 2004 by Franck Marchis ( University of California, Berkeley ), Pascal Descamps, Daniel Hestroffer and Jérôme Berthier ( Observatoire de Paris ) with the VLT -8.2-meter telescope Yepun of the European Southern Observatory on Cerro Paranal in Chile discovered. The project manager Marchis waited with the data processing because he was waiting for the completion of a new image processing program. Shortly before his planned vacation trip in March 2005, he received a small note from Pascal Descamps with the title “87 Sylvia is triple?”, Which meant that he could make out two companions in several pictures of Sylvia. The entire team immediately started analyzing the data, sent a paper to the Asteroid Comet Meteor Conference in August in Armação dos Búzios near Rio de Janeiro, and on the same day submitted a name proposal to the International Astronomical Union (IAU). The discovery was announced almost exactly one year after the discovery on August 10, 2005; the moon was given the provisional designation S / 2004 (87) 1 . The discovery made the system the first known triple asteroid system.
On August 11th, both moons were officially named. Since Sylvia is named after Rhea Silvia , the team around Franck Marchis suggested naming the two Sylvia satellites after Romulus and Remus , the children of Rhea Sylvia and the god Mars , who were raised by a she-wolf. In Roman mythology, Romulus slew his twin brother Remus in an argument over who the newly founded city of Rome should be named after.
Track properties
Remus circles Sylvia on a prograde , almost perfect circular path at an average distance of 702 kilometers from the center, which corresponds to 5.5 Sylvia radii. The eccentricity of the orbit is at most 0.01, the orbit is 2.0 ° inclined to the equator of Sylvia . The orbit of the outer moon Romulus is on average about 650 km from Remus' orbit.
Remus orbits Sylvia in 1 day, 8 hours and 57 minutes, which corresponds to about 1,727.9 orbits in a Sylvia year (about 6.5 earth years). Remus' orbit is believed to be stable because it is well within Sylvia's Hill radius of 40,000 miles, but also well outside of synchronous orbit.
Physical Properties
Remus has a diameter of 10.6 km (about 1/24 of the central body), based on the assumed equal reflectivity of 5%, corresponding to the Sylvia . The surface is therefore extremely dark.
The mass of Remus was previously calculated to be 9.32 · 10 14 .
Assuming a mean diameter of 10.6 km, the surface area is around 353 km 2 , which is roughly between the area of Malta and the state of Bremen .
The system was probably created as a result of a collision between two asteroids. From the large fragments of such a collision, the large parent asteroid was formed, while the moons are probably smaller debris from the collision that were attracted by the new asteroid. Remus is therefore like the mother body of the Rubble Pile type .
exploration
Since its discovery in 2004, Remus could only be observed through terrestrial telescopes and its orbital elements could be determined. Should the nature of the origin of the system be confirmed, the group around Franck Marchis assumes that discoveries of triple systems in the main belt will increase. So far (as of April 2020) fifteen are known.
From the surface of Remus, the mother body Sylvia appears huge, it would cover an area of around 30 ° by 18 °, while the size of the second companion Romulus varies between 1.6 ° and 0.5 °.
See also
media
Web links
- Wm. Robert Johnston: (87) Sylvia, Romulus and Remus (English)
- Observatoire de Paris: The moonlets of asteroid 87 Sylvia: Remus and Romulus (English)
- Uni Berkeley: First triple asteroid system found August 10, 2005
Individual evidence
- ^ Daniel WE Green: IAUC No. 8582: Satellites of (87) Sylvia naming (2005). Retrieved September 4, 2017 .
- ↑ Yu Jiang et al .: Dynamical Configurations of Celestial Systems Comprised of Multiple Irregular Bodies (2016). Retrieved September 4, 2017 .
- ↑ Julia Fang et al .: Orbits, Masses, and Evolution of Main Belt Triple (87) Sylvia . 2016, bibcode : 2012AJ .... 144 ... 70F .