Techniques d'observation spectroscopique d'astéroïdes
Techniques d'observation spectroscopique d'astéroïdes
Techniques d'observation spectroscopique d'astéroïdes
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120 CHAPTER 7. SPECTRAL PROPERTIES OF MAIN BELT ASTEROIDS<br />
Relative Reflectance<br />
1.1<br />
1<br />
0.9<br />
0.8<br />
0.7<br />
0.6<br />
(a)<br />
(854) Frostia: NIR<br />
(854) Frostia:V<br />
1 1.5 2 2.5<br />
Wavelength [um]<br />
Relative Reflectance<br />
(b)<br />
1.1<br />
1<br />
0.9<br />
0.8<br />
0.7<br />
0.6<br />
0.5<br />
Frostia<br />
V<br />
Sv<br />
Sr<br />
1 1.5 2 2.5<br />
Wavelength [um]<br />
0.45<br />
0.4<br />
0.38<br />
tel-00785991, version 1 - 7 Feb 2013<br />
Relative Reflectance<br />
(c)<br />
0.4<br />
0.35<br />
0.3<br />
0.25<br />
Frostia<br />
ALHA76005,85<br />
1 1.5 2 2.5<br />
Wavelength [um]<br />
Relative Reflectance<br />
(d)<br />
0.36<br />
0.34<br />
0.32<br />
0.3<br />
0.28<br />
0.26<br />
0.24<br />
0.22<br />
Frostia<br />
Y−793591,90<br />
1 1.5 2 2.5<br />
Wavelength [um]<br />
Figure 7.2: a) The visible and NIR spectrum of (854) Frostia; b) A polynomial fit for the spectrum of (854) Frostia<br />
compared with the theoretical spectra of V, Sv and Sr types; c) the comparison between the spectrum of (854)<br />
Frostia and the spectrum of a sample from ”ALHA76005,85” meteorite; d) the comparison between the spectrum<br />
of (854) Frostia and the spectrum of a sample from Y − 793591,90 meteorite.<br />
movement of components around their center of mass can be validated by observational results<br />
(obtained for instance using adaptive optics); results of their dynamics will be constrained by<br />
the physical model which takes into account shape, bulk density, and internal properties of<br />
the components. Furthermore, the interaction between a dynamical and a physical model allows<br />
the derivation of the most probable configuration of the system (in terms of separation of<br />
components, orbital parameters, shapes and densities).<br />
(854) Frostia is a Main-Belt asteroid with an absolute magnitude H = 11.8mag. Its semimajor<br />
axis is a=2.36832AU (Table 7.1). This asteroid was observed intensely in photometry<br />
[Behrend et al., 2006] by amateurs and professional astronomers 4 . (854) Frostia is a slow rotator<br />
with a synodic period of 37.728hrs. Its regular lightcurve with an amplitude of 0.33mag<br />
presents, for short periods of time, important attenuation, of about 0.7−0.8mag. The large<br />
magnitude is very well explained by mutual eclipse/occultation events for an object with two<br />
4 http://obswww.unige.ch/~behrend/page_cou.html
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