Bibcode
Pinilla-Alonso, Noemí; Popescu, Marcel; Fernández-Valenzuela, Estela; Licandro, Javier; Duffard, René; Castro, Joel; Murillo, Raúl M.; Grundy, William; Reyes-Ruiz, Mauricio; Silva, José
Bibliographical reference
American Astronomical Society, DPS meeting #50, id.200.02
Advertised on:
10
2018
Citations
0
Refereed citations
0
Description
Trojans are a significant portion of the small bodies population located
within two clouds in the L4 and L5 Lagrangian points of Jupiter's orbit.
The study of primitive small bodies is relevant to the origin and nature
of volatile and organic material in the early Solar System. Dedicated
studies of the nature of these bodies can significantly improve our
understanding of their nature, origin and evolutionary mechanisms. Lucy,
a mission of the NASA's Discovery Program, is planned to launch in
October 2021 for a 12-year journey. Lucy will explore seven different
primitive small bodies, six of which will be Trojans. The mission will
use a suite of remote sensing instruments to map the geology, surface
color, composition, thermal and other physical properties of the targets
at close range. Our international team performed observations during
2017 and 2018 to record the light-curve of the mutual events of the
binary system formed by Patroclus and Menoetius, providing a unique
opportunity to refine their orbit characteristics as well as other
properties of the system (sizes, shape, and mass of both objects).
Patroclus is the first binary trojan to be discovered. Previous studies
by Marchis, et al. (2016, Nature, 439) determined the mutual orbit of
the system to have a period of 4.283 ± 0.004 days and a semimajor
axis of 680 ± 20 km, leading to a system mass of (1.36 ±
0.11) x 1018kg and an average bulk density of 0.8 ±
0.2 g cm-3. When the plane of their mutual orbit is aligned
with the direction to the Sun or to an observer, Patroclus and Menoetius
take turns eclipsing or occulting one another. Such an alignment occurs
during mutual event seasons, twice during the ˜12 year orbit
around the Sun. We show, for the first time, a collection of
light-curves that are the result of about 20 detections. Our analysis
puts a special focus on the differences between the observations and the
models of the orbit (Grundy et al. 2018, Icarus 305) providing unique
and crucial information that includes the possible topographic variation
on Menoetius' south pole, a refinement to the orbit model, and improved
predictions for shadowing and occultation events.