(9) Metis verfinstert HIP 78193


What we know from the occultation and the light curve:
-the form of a potato looks sensefull
-the rotation axis is near the ecliptic
-at the occultation we have seen Metis on a position near the minor axis.
-the albedo was 25% to low.

Metis is one of the 400 minor planets with a rotation model in the DAMIT-Database.
metisjd1.gif metisjd2.gif

There are 2 models. An old convex model and a new more complex nonconvex model. It´s interesting to compare models and reality.

The picture shows both models.
2 times at the equator and one time on the pole.

The eclipse is a possibility to check the models:
umriss111.gif umriss716.gif

The old convex model fits better than non-convex model 716.

The deficits of model 716 were also visible at a eclipse from 2008 (JD 2454721.76736)
umriss111.gif umriss716.gif

It make sense to use only model 111.
Also other eclipses fits well to model 111:

The DAMIT database delivers always 2 views. One with the phase at the calculated time and one without phase-effects.
achsanderung.gif The difference between the picture-brightness is 13088115 : 19202888 or 30% That´s nearby the measured value of 25%

The measured difference in the Albedo is completely explainable by the phase.

The following animation shows the rotation at the 7. of March 2014. 72 pictures with 5 degree difference are connected to get this result.

The model is orientated north-south east-west.
As presumed the rotation axis is near the equator.

But how does the model fit to the measured light curve?


The light curve of the model fits the reality. There are 2 mountains. The first one has the right value and also the valleys are perfect.

On the second view there are differences. The second mountain is too low.
-the model is good but not perfect.

During the maximum the brightness of Metis is 20% higher than during the occultation. But the major-axis is in the maximum not 20% longer.
The minor planet is not a perfect rotation-ellipsoid. The rising brightness depends on a better illumination on the northern part of asteroid.

3metis7axis1.gif 3metis7axis2.gif


Messung am 7.3.2014
Metis II Realität und model
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