Romulus (moon)
| (87) Sylvia I (Romulus) | |
|---|---|
|
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| Asteroid Sylvia with Romulus and Remus | |
| Provisional or systematic name | S / 2001 (87) 1 |
| Central body | (87) Sylvia |
| Properties of the orbit | |
| Major semi-axis | 1351.35 ± 0.01 km |
| Periapsis | 1,342.03 km |
| Apoapsis | 1360.67 km |
| eccentricity | 0.0069 ± 0.0037 |
| Orbit inclination | 1.7 ± 1.0 ° |
| Orbital time | 3.654 ± 0.024 d |
| Mean orbital velocity | 0.027 km / s |
| Physical Properties | |
| Medium diameter | 10.8 ± 5.6 km |
| Dimensions | 7.33 + 4.7 / -2.3 · 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 |
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| Date of discovery | February 18, 2001 |
| Remarks | Larger moon of the Sylvia system |
Romulus is the outer and larger of the two moons of the main belt asteroid (87) Sylvia ( Cybele group ). Its mean diameter is around 11 kilometers, which is about 1/23 the diameter of Sylvia.
Discovery and naming
Romulus was discovered on February 18, 2001 by Jean-Luc Margot and Michael E. Brown at the Keck Observatory II on Mauna Kea in Hawaii . Romulus was found at 0.59 arc seconds from Sylvia, with an apparent magnitude difference of 6.24 ± 0.2. The discovery was announced on February 23, 2001; the moon was given the provisional designation S / 2001 (87) 1 .
In 2004, the team of astronomers Franck Marchis ( University of California, Berkeley ) as well as Pascal Descamps, Daniel Hestroffer, and Jérôme Berthier ( Observatoire de Paris ) discovered another companion of Sylvia, which made the system the first known triple asteroid system.
On August 11, 2005, 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 is said to be in 753 BC. BC founded the city of Rome , named it and slain his twin brother Remus in anger after he became the first king of Rome.
Track properties
Romulus orbits Sylvia on a prograde , almost perfect circular orbit at an average distance of 1351 kilometers from the center (about 10.7 Sylvia radii). The orbit eccentricity is at most 0.007, the orbit is 1.7 ° inclined to the equator of Sylvia . The orbit of the inner moon Remus is on average about 650 km from Romulus' orbit.
Romulus orbits Sylvia in 3 days, 15 hours and 42 minutes, which corresponds to about 649.3 orbits in a Sylvia year (about 6.5 earth years). Romulus orbit is believed to be stable because it is well within Sylvia's Hill radius of 40,000 miles, but also well outside of the synchronous orbit.
Physical Properties
Romulus has a diameter of 10.8 km (about 1/23 of the central body), based on the assumed equal reflectivity of 5%, corresponding to Sylvia . The surface is therefore extremely dark.
Assuming a mean diameter of 10.8 km, the surface area is about 366 km 2 , which is roughly between the area of Malta and the state of Bremen .
The mass of Romulus has so far been calculated to be 7.33 · 10 14 .
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. Romulus is therefore like the mother body of the Rubble Pile type ; however, it appears in the spectrum of a somewhat bluer color.
exploration
Immediately after the discovery, the Sylvia system was observed with the Hubble space telescope . Five days after the discovery, the Hubble team was able to confirm the Romulus through the visibility in six images. The second moon Remus was not discovered.
When viewed from the surface of Romulus, Sylvia covers a region of the sky measuring 16 ° × 10 °, while Remus' apparent size varies between 0.62 ° and 0.19 °.
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)
Individual evidence
- ↑ Daniel WE Green: IAUC No. 7588: S / 2001 (87) 1 discovery publication (2001). Retrieved September 4, 2017 .
- ^ Daniel WE Green: IAUC No. 7590: S / 2001 (87) 1 confirmation (2001). Retrieved September 4, 2017 .
- ^ 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 .