S / 2005 (809) 1
| (809) Lundia I (S / 2005 (809) 1) | |
|---|---|
| Provisional or systematic name | S / 2005 (809) 1 |
| Central body | (809) Lundia |
| Properties of the orbit | |
| Major semi-axis | 15.8 km |
| Periapsis | unknown |
| Apoapsis | unknown |
| Orbital time | 0.6423225 d |
| Physical Properties | |
| Albedo | 0.379 ± 0.084 |
| Medium diameter | 6.1 ± 2.1 km |
| Medium density | 1.67 ± 0.04 - 2.5 ± 0.2 g / cm 3 |
| Sidereal rotation | 15 h 24.9 min 56.7 s |
| Surface temperature | 165 - 180 (−108 to −93 ° C) K |
| discovery | |
| Explorer |
|
| Date of discovery | September 18, 2005 |
| Remarks | Smaller component of the Lundia system |
S / 2005 (809) 1 is the 11.6% smaller component (" moon ") of the inner main belt asteroid (809) Lundia . Since S / 2005 (809) 1 has a similar size to Lundia, this system can also be understood as a double asteroid system.
Discovery and naming
S / 2005 (809) 1 was created on August 10, 2000 by a team of astronomers consisting of Agnieszka Kryszczyńska, Tomasz Kwiatkowski, R. Hirsch, Magdalena Polińska, K. Kamiński and Anna Marciniak by observing the light curve at the Astronomical Observatory of Adam Mickiewicz University discovered in Poznan ( Poland ). The discovery was announced on October 1, 2005; the moon was given the provisional designation S / 2005 (809) 1 .
Since the companion's discovery, the name "Lundia" has officially been used for the larger component, while the designation S / 2005 (809) 1 applies to the smaller component. But the name is often used for the whole system.
In total, the asteroid was observed through several earth-based telescopes, a total of 2408 times within 101 years. (As of Sept. 2017)
Track properties
Orbit
S / 2005 (809) 1 and Lundia orbit each other around the common center of gravity on an orbit at a distance of 18.5 km (approx. 5.4 Lundia and 6.1 S / 2005 (809) 1 radii) from the centers of the two bodies; this results in an average distance between the surfaces of the two bodies of 12 km. These do not touch, and Lundia is therefore not a contact binary , as is the case with (216) Cleopatra . The orbital eccentricity and inclination are currently still undetermined.
The orbit time of S / 2005 (809) 1 is equal to the rotation and is around 15 hours and 24.9 minutes.
rotation
S / 2005 (809) 1 rotates once around its axis every 15 hours and 24.9 minutes. Since the orbit time is the same as the rotation time, and the main body Lundia behaves in the same way, it is a doubly bound rotation . This means that both bodies always turn to the same side, as is the case with the Pluto / Charon or Antiope A / B systems . The prerequisite for this is a similar mass ratio and a narrow orbit of the two bodies.
As Lundia performs S / 2005 (809) in a 1-year Lundia 1961.9 own twists .
Physical Properties
size
The most precise determination of the diameter ( geometric mean ) is 6.1 km. The companion thus has 88.4% of the diameter of the main body. The exact dimensions are currently unclear, but at least one of the two components has an elongated shape. The measured single body value of 9.6 km relates to both Lundia components.
Assuming a mean diameter of 6.1 km, the surface area is around 117 km 2 , which is slightly larger than the area of the German Müritz or the Swiss Lake Lucerne .
Such binary systems are rather a rarity in the main belt. The binary systems in the main belt with a size ratio of over 88% for the smaller component include Lundia and the systems (617) Patroclus / Menoetius (an L 5 -Jupiter Trojan system , 92, 4%) and (69230) Hermes / S / 2003 (69230) 1 (90%). In the Kuiper Belt, however, such systems are not uncommon.
| year | Dimensions km | source |
|---|---|---|
| 2009 | 6.1 ± 2.1 | Kryszczyńska u. a. |
| 2014 | 6.7 | Kryszczyńska u. a. |
The most precise determination is marked in bold .
internal structure
S / 2005 (809) 1, like Lundia, belongs to the Type V asteroids and therefore has a very bright surface with an albedo of 0.379. The mean density of 2.5 g / cm 3 is an indication that it is not a compact body, but rather a rubble pile , an accumulation of dust and rocks that is interspersed with cavities. The porosity is estimated at 13 to 30%.
The total mass of the system is . Since the companion has only slightly less mass than the main body, the barycentre of the system is also almost in the middle.
The mean surface temperature is around 165 to 180 K (−108 to −93 ° C) and can rise to a maximum of 260 to 280 K (−13 to +7 ° C) at noon.
See also
Web links
- Wm. Robert Johnston: (809) Lundia (English)
- Representation of 3 – D model from (809) Lundia and S / 2005 (809) 1 (English)
Individual evidence
- ^ Daniel WE Green: IAUC No. 8614: S / 2005 (809) 1 Discovery Publication (October 2005). Retrieved September 22, 2017 .
- ↑ JPL: (809) Lundia at the JPL. Retrieved September 22, 2017 .
- ^ Daniel WE Green: (809) Lundia (October 2005). Retrieved September 22, 2017 .
- ↑ Agnieszka Kryszczyńska et al: New binary asteroid 809 Lundia I. Photometry and modeling (February 2009). Retrieved September 22, 2017 .
- ↑ Agnieszka Kryszczyńska et al: Non-convex model of the binary asteroid (809) Lundia and its density estimation (2014). Retrieved September 22, 2017 .
- ↑ Przemyslaw Bartczak et al: A new non-convex model of the binary asteroid (809) Lundia obtained with the SAGE modeling technique (July 2017). Retrieved September 22, 2017 .