Title:

The "La Palma" Spectroscopic Program on Solar System Icy Minor Planet
Bodies.



Javier Licandro
Isaac Newton Group of Telescopes &
Instituto de Astrofisica de Canarias




Abstract:


Late 2000 we started a long-term spectroscopic program to study the
surface of tree related populations of icy minor planet bodies:
trans-neptunian objects (TNOs), Centaurs and comet nuclei, using several
telescopes at the "El Roque de los Muchachos" Observatory (ORM, La Palma,
Spain).  These objects are remnant planetesimals from the early solar
system formation stages and are probably the most pristine bodies in the
Solar System. The study of their surface properties can provide key
information on the composition and early conditions in the pre-solar
nebula Spectroscopy, in particular in the near-infrared region, is a
powerful method for remote determination of the composition of volatile
surface components of the outer Solar System objects. To obtain the the
near-infrared spectra we take advantage of the unique, high throughput,
low resolution spectroscopic mode of NICS, the Near Infrared Camera
Spectrograph attached to the Italian 3.6m Telescopio Nazionale Galileo
(TNG). NICS uses an Amici prism disperser which yields a complete 0.8-2.4
$\mu$m spectrum that allowed us to take the first ever obtained near
infrared spectra of a TNO with a 4m class telescope (Licandro et al.
2001). Since we started, we obtained the near-infrared spectra of 6 TNOs,
7 Centaurs and 3 comet nuclei. In some cases we also did visible
spectroscopy with the TNG or the 4.2m William Herschel Telescope. The
spectra are analyzed in the framework of the simple one-dimensional
geometrical-optics formulation by Shkuratov et al. (1999) to derive
mineralogical information.  The program, the instruments, and the main
results are presented in this talk.