Orbital evolution under the action of fast interstellar gas flow

Abstract

We investigate the orbital evolution of an interplanetary dust particle under the action of an interstellar gas flow. We present the secular time derivatives of the particle's orbital elements, for arbitrary orbit orientation. An important result concerns the secular evolution of the semimajor axis. The secular semimajor axis of the particle on a bound orbit decreases under the action of fast interstellar gas flow. In this paper, we discuss the possible types of evolution of other Keplerian orbital elements. Also, we compare the influences of the Poynting–Robertson effect, the radial solar wind and the interstellar gas flow on the dynamics of the dust particle in the outer planetary region of the Solar system and beyond, up to 100 au. We study the evolution of a putative dust ring in the zone of the Edgeworth–Kuiper belt. The non‐radial solar wind and the gravitational effect of the major planets might have an important role in this zone. We take into account both these effects. The low‐inclination orbits of micrometre‐sized dust particles in the belt are not stable, because of the fast increase of eccentricity caused by the long‐term monodirectional interstellar gas flow and subsequent planetary perturbations – the increase of eccentricity leads to the planet‐crossing orbits of the particles. Gravitational and non‐gravitational effects are treated in a way that fully respects physics. As a consequence, some of the published results have turned out to be incorrect. Moreover, in this paper we treat the problem in a more general way than it has been presented up to now. The influence of the fast interstellar neutral gas flow should not be ignored in the modelling of the evolution of dust particles beyond planets.

Dust particles in mean motion resonances influenced by an interstellar gas flow

“…Secular time derivatives of semimajor axis, eccentricity and argument of perihelion in the planar case were calculated in Klačka et al (2009). In Pástor, Klačka & Kómar (2011) secular time derivatives of all Keplerian orbital elements for arbitrary orientation of the orbit with respect to interstellar gas velocity vector were calculated. The secular time derivatives of orbital elements were in Pástor et al (2011) derived under the assumptions (a) that the acceleration caused by the IGF is small compared to the gravitation of a central object, (b) that the speed of the IGF is large in comparison with the speed of the dust particle (speeds are determined with respect to the central object) and (c) that the speed of the IGF is large also in comparison with the mean thermal speed of the gas in the flow (Mach number 1).…”

On the stability of dust orbits in mean-motion resonances perturbed by from an interstellar wind

“…The angle between the direction of the velocity vector of the interstellar gas and Neptune's orbital plane is 3.7 • . The obtained orbital evolutions of the dust particles under the action of the PR effect, the radial solar wind, and the IGF are almost indistinguishable from the coplanar case due to the small value of this angle (Pástor, Klačka & Kómar 2011). This can be understood using the secular time derivatives of the orbital elements for an arbitrary orientation of the orbit caused by the considered effects.…”

“…We neglected the Lorentz force, which is only important for submicrometer particles (Dohnanyi 1978;Leinert & Grün 1990;Dermott et al 2001). The interval between collisions is on the order of 10 7 years for a particle with R d = 2 µm beyond the orbit of Neptune (Pástor, Klačka & Kómar 2011). We assumed that the atoms are specularly reflected at the surface of the dust grain (δ i = 1 in Eq.…”

Properties of interstellar wind leading to shape morphology of the dust surrounding HD 61005

“…The increase of the semi-major axis should create the observed swept-back structure in Maness et al (2009). However, Pástor, Klačka & Kómar (2011) and Pástor (2012b) analytically proved that for the dust particles on bound orbits, the semimajor axis always decreases independently of an orientation of the orbit with respect to the interstellar gas velocity vector.…”