69 research outputs found
Effects of immersed moonlets in the ring arc particles of Saturn
Ring arcs are the result of particles in corotation resonances with nearby
satellites. Arcs are present in Saturn and Neptune systems, in Saturn they are
also associated with small satellites immersed on them. The satellite Aegaeon
is immersed in the G~ring arc, and the satellites Anthe and Methone are
embedded in arcs named after them. Since most of the population of the arcs is
formed by m-sized particles the dissipative effects, such as the plasma
drag and the solar radiation force, decrease the lifetime of the arcs. We
analysed the effects of the immersed satellites on these arcs by computing the
mass production rate and the perturbation caused by them in the arc particles.
By comparing the lifetime of the particles and the mass production rate we
concluded that Aegaeon, Anthe and Methone did not act as sources for their
arcs. We took a step further by analysing a hypothetical scenario formed by an
immersed moonlet of different sizes. As a result we found that regardless the
size of the hypothetical moonlet (from about 0.10 km to 4.0 km) these moonlets
will not act as a source. These arcs are temporary structures and they will
disappear in a very short period of time
Production and fate of the G ring arc particles due to Aegaeon (Saturn LIII)
The G ring arc hosts the smallest satellite of Saturn, Aegaeon, observed with
a set of images sent by Cassini spacecraft. Along with Aegaeon, the arc
particles are trapped in a 7:6 corotation eccentric resonance with the
satellite Mimas. Due to this resonance, both Aegaeon and the arc material are
confined to within sixty degrees of corotating longitudes. The arc particles
are dust grains which can have their orbital motions severely disturbed by the
solar radiation force. Our numerical simulations showed that Aegaeon is
responsible for depleting the arc dust population by removing them through
collisions. The solar radiation force hastens these collisions by removing most
of the 10m sized grains in less than 40 years. Some debris released from
Aegaeon's surface by meteoroid impacts can populate the arc. However, it would
take 30,000 years for Aegaeon to supply the observed amount of arc material,
and so it is unlikely that Aegaeon alone is the source of dust in the arc
Neptune's ring arcs confined by coorbital satellites: dust orbital evolution through solar radiation
Voyager 2 images confirmed the presence of ring arcs around Neptune. These
structures need a confinement mechanism to constrain their spreading due to
collisions, dissipative forces, and differential keplerian motion. Here we
report the results of a set of numerical simulations of the system formed by
Neptune, the satellite Galatea, dust ring particles, and hypothetical
co-orbital satellites. This dynamical system depicts a recent confinement
mechanism formed by four co-orbital satellites being responsible for the
azimuthal confinement of the arcs, while Galatea responds for their radial
confinement. After the numerical simulations, the particles were divided into
four groups: particles that stay in the arcs, transient particles, particles
that leave the arcs to the Adams ring, and particles that collide with the
co-orbital satellites. Our results showed that in all arcs the lifetime of the
smaller particles is at most 50 years. After 100 years about 20% of the total
amount of larger particles is still present in the arcs. From our numerical
simulations, the particles should be present in all arcs after 30 years, the
period between the discovery of the arcs up to now. Our results can not explain
the disappearance of the leading arcs, Liberte and Courage unless the arcs are
formed by different particle sizes. Analysis of the dust production, due to
collisions between interplanetary debris onto the surface of the co-orbital
satellites, ruled out the hypothesis that small satellites close to or in the
arc the structure could be its source.Comment: 9 pages, 12 figure
Appearance of Saturn's F ring azimuthal channels for the anti-alignment configuration between the ring and Prometheus
In this article we explore the aspect of the F ring with respect to the
anti-alignment configuration between the ring and Prometheus. We focus our
attention on the shape of the F ring's azimuthal channels which were first
reported by Porco et al. (2005) and numerically explored by Murray et al.
(2005), who found excellent agreement between Cassini's ISS reprojected images
and their numerical model via a direct comparison. We find that for
anti-alignment the channels are wider and go deeper inside the ring material.
From our numerical model we find a new feature, an island in the middle of
the channel. This island is made up of the particles that have been perturbed
the most by Prometheus and only appears when this satellite is close to
apoapsis. In addition, plots of the anti-alignment configuration for different
orbital stages of Prometheus are obtained and discussed here.Comment: Number of pages: 12, number of tables: 1, number of figures:
Mapping and maneuvering long-term natural orbits around Titania, a satellite of Uranus
In this work, we present the results of a set of numerical simulations
carried out to obtain long-duration orbits for a probe around Titania, Uranus'
largest satellite. We also propose orbital maneuvers to extend the lifetime of
some orbits. Titania's and gravitational coefficients and
Uranus' gravitational perturbation are considered. The analysis of lifetime
sensitivity due to possible errors in and values is investigated
using multiple regression models. Simulations were performed for eccentricity
equal 10-4, and lifetime maps were constructed. The results show that
low-altitude orbits have longer lifetimes due to the balance between the
disturbance of Uranus and the gravitational coefficients of Titania. The
results also show that non-zero values of periapsis longitude () and
ascending node longitude () are essential to increase lifespan.
Furthermore, the results indicate that the most economical maneuver occurs for
final orbits of radius equal to 1050 km, this is observed for all inclination
values.Comment: 5 pages, 3 figures, 1 table. arXiv admin note: substantial text
overlap with arXiv:2203.1444
LOCAL VARIABILITY IN THE ORBIT OF SATURN'S F RING
This work was supported by the Science and Technology Facilities Council (grant number ST/F007566/1)
On the stability around Chariklo and the confinement of its rings
Chariklo has two narrow and dense rings, C1R and C2R, located at 391 km and
405 km, respectively. In the light of new stellar occultation data, we study
the stability around Chariklo. We also analyse three confinement mechanisms, to
prevent the spreading of the rings, based on shepherd satellites in resonance
with the edges of the rings. This study is made through a set of numerical
simulations and the Poincar\'e surface of section technique. From the numerical
simulation results we verify that, from the current parameters referring to the
shape of Chariklo, the inner edge of the stable region is much closer to
Chariklo than the rings. The Poincar\'e surface of sections allow us to
identify the first kind periodic and quasi-periodic orbits, and also the
resonant islands corresponding to the 1:2, 2:5, and 1:3 resonances. We
construct a map of a versus e space which gives the location and width of the
stable region and the 1:2, 2:5, and 1:3 resonances. We found that the first
kind periodic orbits family can be responsible for a stable region whose
location and size meet that of C1R, for specific values of the ring particles'
eccentricities. However, C2R is located in an unstable region if the width of
the ring is assumed to be about 120 m. After analysing different systems we
propose that the best confinement mechanism is composed of three satellites,
two of them shepherding the inner edge of C1R and the outer edge of C2R, while
the third satellite would be trapped in the 1:3 resonance.Comment: Accepted for publication in Astronomy & Astrophysic
Exploring the recycling model of Phobos formation: rubble-pile satellites
Phobos is the target of the return sample mission Martian Moons eXploration
by JAXA that will analyze in great details the physical and compositional
properties of the satellite from orbit, from the surface and in terrestrial
laboratories, giving clues about its formation. Some models propose that Phobos
and Deimos were formed after a giant impact giving rise to an extended debris
disk. Assuming that Phobos formed from a cascade of disruptions and
re-accretions of several parent bodies in this disk, and that they are all
characterized by a low material cohesion, Hesselbrock & Milton (2017) have
showed that a recycling process may happen during the assembling of Phobos, by
which Phobos' parents are destroyed into a Roche-interior ring and reaccreted
several times. In the current paper we explore in details the recycling model,
and pay particular attention to the characteristics of the disk using 1D models
of disk/satellite interactions. In agreement with previous studies we confirm
that, if Phobos' parents bodies are gravitational aggregates (rubble piles),
then the recycling process does occur. However, Phobos should be accompanied
today by a Roche-interior ring. Furthermore, the characteristics of the ring
are not reconcilable with today`s observations of Mars' environment, which put
stringent constraints on the existence of a ring around Mars. The recycling
mechanism may or may not have occurred at the Roche limit for an old moon
population, depending on their internal cohesion. However, the Phobos we see
today cannot be the outcome of such a recycling process.Comment: Accept in The Astronomical Journa
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