Aegis (moon)
| (93) Minerva I (Aegis) | |
|---|---|
| Provisional or systematic name | S / 2009 (93) 1 |
| Central body | (93) Minerva |
| Properties of the orbit | |
| Major semi-axis | 623.5 ± 10 km |
| Periapsis | 623.5 km |
| Apoapsis | 623.5 km |
| eccentricity | 0.000 ± 0.009 |
| Orbit inclination | 89.0 ± 10.9 ° |
| Orbital time | 2.406 ± 0.002 d |
| Physical Properties | |
| Medium diameter | 3.6 ± 1.0 km |
| discovery | |
| Explorer |
|
| Date of discovery | August 16, 2009 |
| Remarks | Larger moon of the Minerva system |
Aegis is the outer and larger of the two moons of the main belt asteroid (93) Minerva . Its mean diameter is 3.6 kilometers, which is about 1/43 of the Minerva diameter.
Discovery and naming
Aegis was discovered on August 16, 2009 at 1:36 pm local time by Franck Marchis, Brent Macomber, Jérôme Berthier, Frédéric Vachier and Joshua P. Emery at the Keck Observatory II on Mauna Kea in Hawaii . Aegis was found at 0.4 arc seconds from Minerva "at 3 o'clock" (270 °), with an apparent magnitude difference of 8. The discovery was announced on August 31, 2009; the moon was given the provisional designation S / 2009 (93) 1 .
On the same day, only 8 minutes later, the team discovered Gorgoneion, another companion of Minerva, which made the system the fifth known multiple asteroid system in the main belt and the eighth overall.
On December 17, 2013, both moons were officially named. They were named not after people but after magical insignia of the goddess Minerva . In Greek mythology , Athena , who corresponded to Minerva in Roman mythology , was Zeus' favorite daughter. For this reason Zeus let her use his artifacts: Aigis , his terrible mirror shield, and his devastating weapon, his beam. Hephaestus originally made the shield from goat skin. It was so strong that not even Zeus could have destroyed it with his lightning bolts. In the middle of the shield was the head of the Gorgoness Medusa , which was severed by Perseus , whom Athena lent the shield, and which, as a protective amulet, could freeze others to stone. As part of the shield, the head of Medusa became known as the Gorgoneion .
Track properties
Aegis orbits Minerva on a prograde , almost perfect circular orbit at an average distance of 651 kilometers from its center (about 9.2 Minerva radii). The orbital eccentricity is around 0, the orbit is 89 ° inclined to the equator of Minerva . The orbit of the inner moon Gorgoneion is on average about 150 miles from Aegis' orbit.
The orbits of both moons are remarkably circular, although the inner Gorgoneion has a slightly more elliptical orbit. Overall, the orbits could be a result of the shape of the mother body Minerva, which is also remarkably round for an asteroid .
Aegis orbits Minerva in 2 days, 9 hours and 44.6 minutes, which corresponds to about 694.3 orbits in one Minerva year (around 4.57 earth years). Conversely, it can be said that one orbit of Aegis takes 9,652 Minerva days. It takes a little more than twice as long as the inner Gorgoneion to complete one cycle.
Physical Properties
The diameter of Aegis is about 3.6 kilometers.
Assuming a mean diameter of 3.6 km, this results in a surface of around 41 km 2 , which is slightly more than the area of the Swiss canton of Basel-Stadt .
exploration
The Minerva observations in 2009 that led to the discovery of Aegis and Gorgoneion continued through 2011. Based on the assumption that the two moons orbit close to the equator of the mother body, it was found that in September 2009 the pole of Minerva was facing the earth, while in March 2011 an edge position of the system was observed.
See also
Web links
- Franck Marchis: A Detailed Picture of the (93) Minerva Triple System (PDF, English )
- Wm. Robert Johnston: (93) Minerva, Aegis and Gorgoneion ( English )
Individual evidence
- ↑ Franck Marchis: The discovery of a new triple asteroid - (93) Minerva moon discovery ( English )
- ↑ Franck Marchis: Asteroid Minerva finds its magical weapons in the sky Moon naming ( English )