S / 2004 (45) 1
| (45) Eugenia II (S / 2004 (45) 1) | |
|---|---|
| Provisional or systematic name | S / 2004 (45) 1 |
| Central body | (45) Eugenia |
| Properties of the orbit | |
| Major semi-axis | 610.59 ± 0.06 km |
| Periapsis | 543.4 km |
| Apoapsis | 677.8 km |
| eccentricity | 0.11 ± 0.02 |
| Orbit inclination | 18.0 ° |
| Orbital time | 1.7930 ± 0.0008 d |
| Mean orbital velocity | 0.0181 km / s |
| Physical Properties | |
| Medium diameter | 5 ± 1 km |
| Medium density | ≈ 1.12 ± 0.3 g / cm 3 |
| Acceleration of gravity on the surface | ≈ 0 m / s 2 |
| Escape speed | ≈ 0 m / s |
| discovery | |
| Explorer |
|
| Date of discovery | February 14, 2004 |
| Remarks | Smaller moon of the Eugenia system |
S / 2004 (45) 1 is the smaller, inner moon of the main belt asteroid (45) Eugenia . Its discovery led to the second known asteroid multiple system in the solar system .
Discovery and naming
S / 2004 (45) 1 was discovered on February 14, 2004 by a team of astronomers consisting of Franck Marchis, M. Baek, Pascal Descamps, Jérôme Berthier, Daniel Hestroffer and Frédéric Vachier. The moon was identified in three images that were taken using adaptive optics with the 8.2 m “Yepun” VLT telescope on Cerro Paranal in Chile . The discovery was announced on March 7, 2007; the moon was given the provisional designation S / 2004 (45) 1 .
The name Princesse was proposed and mostly used for the moon , but an official name confirmation from the IAU is still pending.
Eugenia's first moon, Petit-Prince, was discovered as early as 1998 ; the discovery of S / 2004 (45) 1 caused the system after (87) Sylvia to grow into the second known multiple asteroid system. So far the system could only be observed through earth-based telescopes.
Track properties
S / 2004 (45) 1 circles Eugenia on a prograde , slightly elliptical orbit between 543 and 678 km from its center (major orbit half-axis 610.59 km or 6 Eugenia radii). The orbit eccentricity is 0.11, the orbit is 18.1 ° inclined to the equator of Eugenia . With this, the moon moves well within Eugenia's Hill sphere of 37,000 km.
The orbit of the moon lies almost in the middle between Eugenia and Petit – Prince, from which it is on average about 554 km away, but it is also somewhat more eccentric and inclined than the orbit of the outer neighbor, whose orbit is almost circular. Overall, the Eugenia system seems to be quite stable; it experiences slight interference from the sun and, to a lesser extent, from the mutual interactions between the moons. There is no evidence of orbital resonance , including the Kozai effect , which suggests that the inclinations of the moons' orbits were not caused by the influence of Eugenia.
S / 2004 (45) 1 orbits Eugenia in 1 day 19 hours and 2 minutes, which corresponds to about 913.6 orbits in one Eugenia year (around 4.5 earth years).
Physical Properties
S / 2004 (45) 1 has a diameter of about 5 km (about 1/40 of the central body), based on the assumed equal reflectivity of 4% corresponding to Eugenia . The surface is therefore extremely dark.
Assuming a mean diameter of 5 km, the surface area is about 78 km 2 , which is slightly more than the area of San Marino .
Like Eugenia, the density is estimated at 1.12 g / cm 3 . It can therefore be assumed that S / 2004 (45) 1 is porous on the inside and, like the mother body, belongs to the rubble piles . Another possibility would be a high occurrence of water ice , which, however, is rather unlikely due to the lack of water in Eugenia.
See also
Web links
Individual evidence
- ^ Daniel WE Green: IAUC No. 8817: S / 2008 (41) 1 Discovery Publication (2008). Retrieved September 4, 2017 .
- ↑ Yu Jiang et al .: Dynamical Configurations of Celestial Systems Comprised of Multiple Irregular Bodies (2016). Retrieved September 4, 2017 .
- ^ Franck Marchis et al .: A Dynamical Solution of the Triple Asteroid System (45) Eugenia (2010). Retrieved September 4, 2017 .