scholarly journals Charge Correlations and Dynamical Instabilities in the Multifragment Emission Process

1996 ◽  
Vol 77 (13) ◽  
pp. 2634-2637 ◽  
Author(s):  
L. G. Moretto ◽  
Th. Rubehn ◽  
L. Phair ◽  
N. Colonna ◽  
G. J. Wozniak ◽  
...  
Keyword(s):  
Emission Process ◽  
Charge Correlations ◽  
Dynamical Instabilities

scholarly journals Formation of compact systems of super-Earths via dynamical instabilities and giant impacts

2019 ◽  
Vol 491 (4) ◽  
pp. 5595-5620 ◽  
Author(s):  
Sanson T S Poon ◽  
Richard P Nelson ◽  
Seth A Jacobson ◽  
Alessandro Morbidelli
Keyword(s):  
Initial Conditions ◽  
Post Processing ◽  
Significant Modification ◽  
Kepler Mission ◽  
Giant Impacts ◽  
Low Mass ◽  
In Situ Formation ◽  
Dynamical Instabilities ◽  
Gaseous Envelopes

ABSTRACT The NASA’s Kepler mission discovered ∼700 planets in multiplanet systems containing three or more transiting bodies, many of which are super-Earths and mini-Neptunes in compact configurations. Using N-body simulations, we examine the in situ, final stage assembly of multiplanet systems via the collisional accretion of protoplanets. Our initial conditions are constructed using a subset of the Kepler five-planet systems as templates. Two different prescriptions for treating planetary collisions are adopted. The simulations address numerous questions: Do the results depend on the accretion prescription?; do the resulting systems resemble the Kepler systems, and do they reproduce the observed distribution of planetary multiplicities when synthetically observed?; do collisions lead to significant modification of protoplanet compositions, or to stripping of gaseous envelopes?; do the eccentricity distributions agree with those inferred for the Kepler planets? We find that the accretion prescription is unimportant in determining the outcomes. The final planetary systems look broadly similar to the Kepler templates adopted, but the observed distributions of planetary multiplicities or eccentricities are not reproduced, because scattering does not excite the systems sufficiently. In addition, we find that ∼1 per cent of our final systems contain a co-orbital planet pair in horseshoe or tadpole orbits. Post-processing the collision outcomes suggests that they would not significantly change the ice fractions of initially ice-rich protoplanets, but significant stripping of gaseous envelopes appears likely. Hence, it may be difficult to reconcile the observation that many low-mass Kepler planets have H/He envelopes with an in situ formation scenario that involves giant impacts after dispersal of the gas disc.

scholarly journals Fermionic systems with charge correlations on the Bethe lattice

2007 ◽  
Vol 460-462 ◽  
pp. 1053-1054
Author(s):  
Ferdinando Mancini ◽  
Adele Naddeo
Keyword(s):  
Bethe Lattice ◽  
Charge Correlations ◽  
Fermionic Systems

scholarly journals Attosecond source generation using polarized gating two-color field combined with unipolar pulse

2016 ◽  
Vol 94 (7) ◽  
pp. 651-658 ◽  
Author(s):  
Liqiang Feng ◽  
Hang Liu
Keyword(s):  
Harmonic Generation ◽  
Extreme Ultraviolet ◽  
Harmonic Spectrum ◽  
High Order ◽  
High Order Harmonic Generation ◽  
Emission Process ◽  
Harmonic Emission ◽  
High Order Harmonic ◽  
Unipolar Pulse ◽  
Color Field

High-order harmonic generation and attosecond extreme-ultraviolet source generation have been theoretically investigated by controlling the two-color polarized gating field combined with the unipolar pulse. The results show that by properly optimizing the polarized two-color field as well as the unipolar pulse, not only is the harmonic cutoff remarkably extended, but the single short quantum path has also been selected to contribute to the harmonic spectrum, resulting in a 313 eV less modulated supercontinuum. Classical and quantum analyses are shown to explain the harmonic emission process. Finally, the proper superposition of harmonics, a series of isolated sub-50 as pulses, can be obtained.

Observation of noisy precursors of dynamical instabilities

1985 ◽  
Vol 31 (2) ◽  
pp. 1077-1084 ◽  
Author(s):  
Carson Jeffries ◽  
Kurt Wiesenfeld
Keyword(s):  
Dynamical Instabilities

scholarly journals Double X/Peanut Structures in Barred Galaxies – Insights from an N–body Simulation

2020 ◽  
Author(s):  
Bogdan C Ciambur ◽  
Francesca Fragkoudi ◽  
Sergey Khoperskov ◽  
Paola Di Matteo ◽  
Françoise Combes
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Large Fraction ◽  
Formation Time ◽  
Dark Matter Halo ◽  
Barred Galaxies ◽  
Pattern Speed ◽  
Nearby Galaxies ◽  
Dynamical Instabilities ◽  
Bow Tie

Abstract Boxy, peanut– or X–shaped “bulges” are observed in a large fraction of barred galaxies viewed in, or close to, edge-on projection, as well as in the Milky Way. They are the product of dynamical instabilities occurring in stellar bars, which cause the latter to buckle and thicken vertically. Recent studies have found nearby galaxies that harbour two such features arising at different radial scales, in a nested configuration. In this paper we explore the formation of such double peanuts, using a collisionless N–body simulation of a pure disc evolving in isolation within a live dark matter halo, which we analyse in a completely analogous way to observations of real galaxies. In the simulation we find a stable double configuration consisting of two X/peanut structures associated to the same galactic bar – rotating with the same pattern speed – but with different morphology, formation time, and evolution. The inner, conventional peanut-shaped structure forms early via the buckling of the bar, and experiences little evolution once it stabilises. This feature is consistent in terms of size, strength and morphology, with peanut structures observed in nearby galaxies. The outer structure, however, displays a strong X, or “bow-tie”, morphology. It forms just after the inner peanut, and gradually extends in time (within 1 to 1.5 Gyr) to almost the end of the bar, a radial scale where ansae occur. We conclude that, although both structures form, and are dynamically coupled to, the same bar, they are supported by inherently different mechanisms.

Dark matter bar evolution in triaxial spinning haloes

2020 ◽  
Vol 15 (S359) ◽  
pp. 446-447
Author(s):  
Daniel A. Marostica ◽  
Rubens E. G. Machado
Keyword(s):  
Dark Matter ◽  
The Other ◽  
Barred Galaxies ◽  
Other Hand ◽  
Dynamical Instabilities

AbstractDark matter bars are structures that may form inside dark matter haloes of barred galaxies. Haloes can depart from sphericity and also be subject to some spin. The latter is known to have profound impacts on the evolution of both stellar and DM bars, such as stronger dynamical instabilities, more violent vertical bucklings and dissolution or impairment of stellar bar growth. On the other hand, dark matter bars of spherical haloes become initially stronger in the presence of spin. In this study, we add spin to triaxial halos in order to quantify and compare the strength of their bars. Using N-body simulations, we find that spin accelerates main instabilities and strengthens the halo bars, although their final strength depends only on triaxiality. The most triaxial halo barely forms a halo bar, showing that flattening opposes to DM bar strengthening and indicating that there is a limit on how flattened the parent structure can be.

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