Optical / IR Interferometry at the VLTI: first direct determination of Asteroids’ sizes and shapes with MIDI

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Sebastiano Ligori

INAF – Torino Astronomical Observatory

torek, 24. 3. 2009, ob 15h v F3

I will give an overview of the Optical Interferometry technique, focusing in particular on the properties and capabilities of ESO’s Very Large Telescope Interferometer. I will discuss the peculiar aspects of this kind of observations and the main limitations one has to take into account when preparing observing proposals for the VLTI. I will then describe the Mid-IR instrument of the VLTI, MIDI, which is successfully in operation since the end of 2003. Finally, I will report on the first successful observation of asteroids with the VLTI: we observed two asteroids, 951 Gaspra and 234 Barbara, for which we were able to determine the diameter and have some information on their shape. Interferometric data, in combination with the spectral information, can be compared with different thermo physical models, and can in principle give us information on the physical characteristics of these objects.