Possible effects of secular resonances in Phobos and Triton

Yokoyama, T.

doi:10.1016/s0032-0633(01)00078-2

Cited by 21 publications

(35 citation statements)

References 30 publications

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“…However, we use this occasion to revisit the connection between orbital effects and internal causes. Past analyses concerned with long term evolution of the satellite orbit [ Burns , 1972, 1992; Lambeck , 1979; Cazenave et al , 1980; Mignard , 1981; Yoder , 1982; Szeto , 1983; Yokoyama , 2002] have consistently assumed that the observed acceleration arises from tidal dissipation within Mars, rather than from interaction with the solar wind [ Russell et al , 1990; Sauer et al , 1995; Mordovskaya et al , 2001], the dust torus [ Hamilton , 1996; Nazzario and Hyde , 1997; Howard et al , 2003], or other possible dissipative effects. Yoder [1982] has raised the issue of dissipation within Phobos.…”

Section: Discussionmentioning

confidence: 99%

Improved estimate of tidal dissipation within Mars from MOLA observations of the shadow of Phobos

et al. 2005

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[1] We report on new observations of the orbital position of Phobos, the innermost natural satellite of Mars, and show that these observations provide an improved estimate of the rate of tidal dissipation within Mars. The observations were made with the Mars Orbiter Laser Altimeter instrument on the Mars Global Surveyor spacecraft. The secular acceleration in along-track orbital motion is conventionally expressed in terms of a quadratic term in mean orbital longitude, which yields s = (dn/dt)/2 = (136.7 ± 0.6) Â 10 À5 deg/yr 2 , where n is the mean motion. The corresponding fractional rate of change in orbital angular velocity is (dn/dt)/n = (6.631 ± 0.029) Â 10 À9 /yr, the highest measured for any natural satellite in the solar system. The energy dissipation rate is (3.34 ± 0.01) MW. Because Phobos is so close to Mars, there are nonnegligible contributions to the tidal evolution from harmonic degrees 2, 3, and 4. However, the elastic tidal Love numbers are observationally constrained only at degree two. The observed acceleration is consistent with that for a homogeneous Maxwell viscoelastic model of Mars with effective viscosity of (8.7 ± 0.6) Â 10 14 Pa s.

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Section: Discussionmentioning

confidence: 99%

Improved estimate of tidal dissipation within Mars from MOLA observations of the shadow of Phobos

et al. 2005

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“…Under normal conditions this value should remain almost unchanged, so that capture of Phobos in the 2n +Ω commensurability is almost certain (Yokoyama 2002), provided that Mars' obliquity is not less than ≈19…”

Section: Mars' Eccentricitymentioning

confidence: 99%

“…In Yokoyama (2002), hereafter PYO, we showed that in the future, Phobos will face some interesting resonance because its semi major axis a is continuously decreasing due to the action of tides. This means that the frequencies associated with the longitude of the node (Ω) and the argument of the pericenter (w) are also varying, so that in the neighbourhood of a specific value of the semi major axis, these frequencies can satisfy resonant relations like k 1Ω + k 2ẇ + k 3 n ≈ 0, where n is the mean motion of the Sun, k i are integers, and dots mean time derivatives.…”

Section: Introductionmentioning

confidence: 97%

On the dynamics of some resonances of Phobos in the future

Yokoyama¹,

Mana²,

Nascimento³

et al. 2004

A&A

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Abstract.A probable capture of Phobos into an interesting resonance was presented in our previous work. With a simple model, considering Mars in a Keplerian and circular orbit, it was shown that once captured in the resonance, the inclination of the satellite reaches very high values. Here, the integrations are extended to much longer times and escape situations are analyzed. These escapes are due to the interaction of new additional resonances, which appear as the inclination starts to increase reaching some specific values. Compared to classical capture in mean motion resonances, we see some interesting differences in this problem. We also include the effect of Mars' eccentricity in the process of the capture. The role played by this eccentricity becomes important, particularly when Phobos encounters a double resonance at a ≈ 2.619R M . Planetary perturbations acting on Mars and variation of its equator are also included. In general, some possible scenarios of the future of Phobos are presented.

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“…A simple calculation shows that for objects with semi-major axis a < a c the inclination remains almost constant with respect to the equator, while for a > a c the object maintains a constant inclination with respect to the orbital plane of the planet, not to the equator. For distances close to a c and depending on the obliquity of the planet, the eccentricity and the motion of the satellite, in general, can become very irregular (Yokoyama 2002).…”

Section: Regular and Irregular Satellitesmentioning

confidence: 99%

Effects of the planetary migration on some primordial satellites of the outer planets

Deienno

Yokoyama

Callegari

et al. 2011

A&A

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Context. During the first hundred million years after the formation of our solar system, the four giant planets are believed to have migrated significantly (by up ≈20 AU). The current scenario and dynamics of the satellites of these planets must be the result of both the initial conditions of their formation and this early extensive migrational episode. Aims. We examine the effects of the migration on the primordial satellites of Uranus. Methods. We use the Nice model to generate templates for the evolution of the four giant planets and record the time history of these planets and important close encounters. The satellites are then added to Uranus and these objects are integrated according to the dynamics stored in the templates. Results. We show that Oberon is the outermost regular satellite of Uranus that is able to resist the close encounters during the extensive migrational episode. Some theories predict that Uranus' satellites can form out to a 57 R U distance from the planet, but we show that even those at ≈27 R U from the planet cannot support the instabilities that appeared during migration. Close objects, such as the current regular satellites of Uranus, can survive quite stably and we are able to place some constraints on the masses of the planetesimals that have close encounters. For instance, if an object with mass ≥10 −9 M approaches at distances < ∼ 23 R U from Uranus, the regular satellites can be destabilized or their eccentricities or inclinations excited to some non-compatibles values. We also find that planet-planetesimal close encounters can generate capture. In this way, we present a promising means of explaining the origin of the irregular satellites of Uranus. The importance of the oblateness of the planet, and the Sun for just-captured planetesimals is also shown.

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Possible effects of secular resonances in Phobos and Triton

Cited by 21 publications

References 30 publications

Improved estimate of tidal dissipation within Mars from MOLA observations of the shadow of Phobos

Improved estimate of tidal dissipation within Mars from MOLA observations of the shadow of Phobos

On the dynamics of some resonances of Phobos in the future

Effects of the planetary migration on some primordial satellites of the outer planets

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