Surface dynamics, equilibrium points and individual lobes of the Kuiper Belt object (486958) Arrokoth

Amarante, A.; Winter, O. C.

doi:10.1093/mnras/staa1732

Cited by 11 publications

(17 citation statements)

References 46 publications

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“…Even when near the body, this method can be used, unlike the method of spherical harmonics (Kaula, 1966; MacMillan, 1936). This procedure using the mascon model has been extensively tested in previous work to study the dynamical environment and surface characteristics of an asteroid (Amarante & Winter, 2020; Winter et al., 2020; Moura et al., 2020). Then, we use the mascons technique to compute Bennu's gravitational force potential numerically as follows:

U (x, y, z) = \overset{N}{\sum_{i = 1}} \frac{μ_{i}}{| r - {boldr}_{i} |},

where x , y , and z represent the coordinates of a particle in the Bennu‐fixed frame measured from the Bennu barycenter, with the unit vectors defined along the minimum, intermediate, and maximum moments of inertia.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…The locations of our computed equilibrium points for particle sizes that are not significantly affected by SRP, that is, stationary points in the Bennu‐fixed frame, are shown in Table 3. They were computed through the mascons technique (Equation ) with the Minor‐Equilibria‐NR package (Amarante & Winter, 2020) where the SRP was implemented (Amarante, 2020b). The number of solutions of Equation depends on the shape and spin period of the body.…”

Section: Equilibrium Points Under Srpmentioning

confidence: 99%

“…Combining the spin rate vector Ω and the gravity attraction (Equation ) of Bennu, the formula for Bennu's gravity power can be obtained (Amarante & Winter, 2020):

P (x, y, z) = (Ω \times r) \cdot (- \nabla U) .

…”

Section: Fallsmentioning

confidence: 99%

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Stability and Evolution of Fallen Particles Around the Surface of Asteroid (101955) Bennu

2021

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• The dynamics of particles orbiting near the equator of Bennu are dominated by eight equilibrium points irregularly located around the asteroid. • Particles smaller than a centimeter are quickly removed from the system by the solar radiation pressure. • Particles larger than a few centimeters, initially orbiting in a spherical cloud around Bennu, preferentially fall onto the surface near high-altitude regions at low equatorial latitudes and close to the north pole.

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U (x, y, z) = \overset{N}{\sum_{i = 1}} \frac{μ_{i}}{| r - {boldr}_{i} |},

Section: Mathematical Modelmentioning

confidence: 99%

Section: Equilibrium Points Under Srpmentioning

confidence: 99%

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Stability and Evolution of Fallen Particles Around the Surface of Asteroid (101955) Bennu

2021

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“…14) as demanded by Seligman et al (2019). On the other hand, the Solar System is no strange to very oblate or flattened bodies, 486958 Arrokoth (2014 MU 69 ), a trans-Neptunian contact binary, has been found to have an average oblateness of p=0.695, with 0.808 for the large lobe and 0.582 for the small lobe (Amarante & Winter 2020).…”

Section: I/2017 U1 ('Oumuamua)mentioning

confidence: 99%

Constraining the orientation of the spin axes of extrasolar minor bodies 1I/2017 U1 (‘Oumuamua) and 2I/Borisov

Marcos

2020

A&A

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Context. The orientation of the spin axis of a comet is defined by the values of its equatorial obliquity and its cometocentric longitude of the Sun at perihelion. These parameters can be computed from the components of the nongravitational force caused by outgassing if the cometary activity is well characterized. The trajectories of known interstellar bodies passing through the Solar System show nongravitational accelerations. Aims. The spin-axis orientation of 1I/2017 U1 (‘Oumuamua) remains to be determined; for 2I/Borisov, the already released results are mutually exclusive. In both cases, the values of the components of the nongravitational force are relatively well constrained. Here, we investigate – within the framework of the forced precession model of a nonspherical cometary nucleus – the orientation of the spin axes of ‘Oumuamua and 2I/Borisov using public orbit determinations that consider outgassing. Methods. We applied a Monte Carlo simulation using the covariance matrix method together with Monte Carlo random search techniques to compute the distributions of equatorial obliquities and cometocentric longitudes of the Sun at perihelion of ‘Oumuamua and 2I/Borisov from the values of the nongravitational parameters. Results. We find that the equatorial obliquity of ‘Oumuamua could be about 93°, if it has a very prolate (fusiform) shape, or close to 16°, if it is very oblate (disk-like). Different orbit determinations of 2I/Borisov gave obliquity values of 59° and 90°. The distributions of cometocentric longitudes were in general multimodal. Conclusions. Our calculations suggest that the most probable spin-axis direction of ‘Oumuamua in equatorial coordinates is (280°, +46°) if very prolate or (312°, −50°) if very oblate. Our analysis favors a prolate shape. For the orbit determinations of 2I/Borisov used here, we find most probable poles pointing near (275°, +65°) and (231°, +30°), respectively. Although our analysis favors an oblate shape for 2I/Borisov, a prolate one cannot be ruled out.

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“…Examples of astronomical dumbbells include the Jupiter Trojan Asteroid 624 Hektor (Descamps, 2015), the comet 8P/Tuttle (Groussin et al, 2019), the comet 103P/Hartley (Harmon, Nolan, Howell, Giorgini, & Taylor, 2011), and the transneptunian object 486958 Arrokoth/Ultima Thule (Amarante & Winter, 2020). Astronomically, these dumbbell shapes can originate from fusion of ellipsoidal precursors, or from elongation.…”

Section: Introductionmentioning

confidence: 99%

Surface Gravity of Rotating Dumbbell Shapes

Lam,

Gidea,

Zypman

2021

Preprint

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We investigate the problem of determining the shape of a rotating celestial object -e.g., a comet or an asteroid -under its own gravitational field. More specifically, we consider an object symmetric with respect to one axis -such as a dumbbell -that rotates around a second axis perpendicular to the symmetry axis. We assume that the object can be modeled as an incompressible fluid of constant mass density, which is regarded as a first approximation of an aggregate of particles.In the literature, the gravitational field of a body is often described as a multipolar expansion involving spherical coordinates (Kaula, 1966). In this work we describe the shape in terms of cylindrical coordinates, which are most naturally adapted to the symmetry of the body, and we express the gravitational potential generated by the rotating body as a simple formula in terms of elliptic integrals. An equilibrium shape occurs when the gravitational potential energy and the rotational kinetic energy at the surface of the body balance each other out. Such an equilibrium shape can be derived as a solution of an optimization problem, which can be found via the variational method. We give an example where we apply this method to a two-parameter family of dumbbell shapes, and find approximate numerical solutions to the corresponding optimization problem.

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Surface dynamics, equilibrium points and individual lobes of the Kuiper Belt object (486958) Arrokoth

Cited by 11 publications

References 46 publications

Stability and Evolution of Fallen Particles Around the Surface of Asteroid (101955) Bennu

Stability and Evolution of Fallen Particles Around the Surface of Asteroid (101955) Bennu

Constraining the orientation of the spin axes of extrasolar minor bodies 1I/2017 U1 (‘Oumuamua) and 2I/Borisov

Surface Gravity of Rotating Dumbbell Shapes

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