90 Antiope A & B

• Press-release published on March 29, 2007
  • The Impossible Siblings (ESO)
  • Binary asteroid revealed as twin rubble piles (UC-Berkeley)
• Same-sized binary asteroid, C type. Orbit model based on 23 positions taken mostly with VLT-NACO in Feb and Mar 2004, and shape of the components from lightcurve observations during mutual events in Jun-Nov 2005 are described in Descamps et al. (2007). Both components are identical with a Dm < 2.5%. The diameter of the lobes , separated by 171+/-1 km, is estimated to 85.8+/- 1 km.
• Orbital elements
• Observations with NACO mostly, plus additional observations with Keck. Contributions of various smaller telescopes for lightcurve photometry.
• A low density (1.25 +/- 0.05 g/cm3)
• Movies
• Nearly perfect Face-on geometry on Feb. 2004
• Predicted and confirmed mutual event configuration in Aug. 2005

Orbital Elements of Antiope A & B System

• J2= 0
• Low eccentricity
• significant porosity
• result published in Descamps et al., (Icarus, 187, 482-499, 2007)
  

Observations

Fig 4a: 90 Antiope A & B observed with VLT-NACO on Feb. 12, 2004. The image was deconvolved with MISTRAL to enhance the sharpness.

MOVIES

90 Antiope A & B in Feb. 2004. As shown on this simulation based on the orbital element and pole solution calculated by Michalowski et al. 2004. The system was perfectly nearly face-on.

Fig 4b and Movie 4A: Animation of 90 Antiope A & B in Feb. 2004 when the system was nearly face-on (click on the image to start the movie)

Using our model combined with the pole solution, we can predict that in August 2005 on 15 days the system will be edge-on. Mutual events will be observable on this relatively bright target (mv=12). Observations of continuous lightcurves are encouraged since they will give the opportunity to better constrain the size and shape of the components, therefore their density.

Fig. 4c and Movies 4B and 4C.: Orbit of Antiope A & B on June-July 2005. Because of the edge-on geometry mutual event will be observable. Animation on the left shows show the system observed with a 8m-class telescope (angular resolution = 70 mas). Animation on the right shows the two components with a sub-km resolution. Note the presence of shadow. [click on the image to start the movies]

Fig. 4d & Movie 4D: Edge-on orbit of Antiope A & B and lightcurve profile [click on the image to start the movie]. Mutual events will happen for 15 days approximately. A campaign of observations will give the opportunity to better estimate the size and shape of the two lobes of the Antiope system.