Bibcode
Campins, Humberto; Fernandez, Yan; Kelley, Michael; Licandro, Javier; Rivkin, Andy; Ziffer, Julie
Referencia bibliográfica
Spitzer Proposal ID #50672
Fecha de publicación:
3
2008
Número de citas
0
Número de citas referidas
0
Descripción
Our primary goal is to characterize the surface composition (and other
properties such as radius, albedo and thermal inertia) of our sample of
Themis-family and Veritas-family asteroids based on their 5 to 14 micron
spectra. We chose these two families for several reasons. First, they
are compositionally primitive (non-igneous) so they can yield
information about their physical and chemical conditions of their
formation environment. Second, their parent bodies formed in the same
region, yet their disruption ages are sharply different: 2.5 Gy and 8.3
My, respectively. This gives us a remarkable opportunity to understand
the evolutionary processes that have affected the asteroids fragments.
For example, Nesvorny et al. (2005) found clear evidence of color
variations between young and old asteroids families. They identified a
well defined trend among primitive asteroids, with the Themis and
Veritas families at opposite ends of this color variation, which they
attribute to space weathering. Finally, both families formed beyond the
'frost line' and some fragments appear to have retained water-ice
reservoirs for the age of the solar system; more specifically Rivkin
(2007) reported the first (preliminary) detection of water ice on 24
Themis. If confirmed, this detection of water-ice opens up interesting
possibilities that could transform of our understanding of these
asteroids. For example, since water ice is not stable on the surface of
24 Themis over the age of the solar system what is its source? What does
this imply about the interior of this asteroid and of the other members
of these two families. Why does 24 Themis not show cometary activity?
These are some of the questions this proposed study will address.
Understanding the abundance of water-ice and hydrated minerals in this
area of the solar system is particularly important, as it may be linked
to the origin of Earth's water. Our total time request is 6.4 hours.