scholarly journals Extra-solar planets: from direct rotation into reverse rotation

2004 ◽  
Vol 202 ◽  
pp. 205-207
Author(s):  
Irina Kitiashvili ◽  
Alexander Gusev
Keyword(s):  
Planetary Systems ◽  
Magnetic Interaction ◽  
Central Star ◽  
Phase Portraits ◽  
Momentum Vector ◽  
Resonance Rotation ◽  
Direct Rotation

We investigate the equation describing the evolution of the kinetic momentum vector for the case of non-resonance rotation of dynamically symmetrical planets by action of gravitational and magnetic interaction with the central star. The obtained gallery of more twenty phase portraits of kinetic momentum evolution illustrates the various regimes of the planetary systems evolution. The analyses of obtained portraits has shown that a direct rotation of the planet may be passed into reverse rotation and vice versa for a rather broad range of the parameters.

scholarly journals Retrograde resonances in compact multi-planetary systems: a feasible stabilizing mechanism

2007 ◽  
Vol 3 (S249) ◽  
pp. 511-516 ◽  
Author(s):  
Julie Gayon ◽  
Eric Bois
Keyword(s):  
Body Problem ◽  
Extrasolar Planets ◽  
Planetary Systems ◽  
Central Star ◽  
Point Of View ◽  
Outer Planet ◽  
Mean Motion Resonances ◽  
Hot Jupiters ◽  
The Stability ◽  
Orbital Data

AbstractMulti-planet systems detected until now are in most cases characterized by hot-Jupiters close to their central star as well as high eccentricities. As a consequence, from a dynamical point of view, compact multi-planetary systems form a variety of the general N-body problem (with N ≥ 3), whose solutions are not necessarily known. Extrasolar planets are up to now found in prograde (i.e. direct) orbital motions about their host star and often in mean-motion resonances (MMR). In the present paper, we investigate a theoretical alternative suitable for the stability of compact multi-planetary systems. When the outer planet moves on a retrograde orbit in MMR with respect to the inner planet, we find that the so-called retrograde resonances present fine and characteristic structures particularly relevant for dynamical stability. We show that retrograde resonances and their resources open a family of stabilizing mechanisms involving specific behaviors of apsidal precessions. We also point up that for particular orbital data, retrograde MMRs may provide more robust stability compared to the corresponding prograde MMRs.

scholarly journals X-Ray Flares and Outflows Driven by Magnetic Interaction Between a Protostar and its Surrounding Disk

1997 ◽  
Vol 163 ◽  
pp. 717-718
Author(s):  
Mitsuru Hayashi ◽  
Kazunari Shibata ◽  
Ryoji Matsumoto
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Plasma Temperature ◽  
Magnetic Interaction ◽  
Central Star ◽  
X Ray ◽  
Mhd Simulations ◽  
Flare Loops ◽  
Hot Plasma ◽  
Dipole Magnetic Field

AbstractHere we present a model of hard X-ray flares and hot plasma outflows (optical jets) observed in protostars. Assuming that the dipole magnetic field of a protostar threads the protostellar disk, we carried out 2.5-dimensional magnetohydrodynamic (MHD) simulations of the diskstar interaction. The closed magnetic loops connecting the central star and the disk are twisted by the rotation of the disk. In the presence of resistivity, magnetic reconnection takes place in the current sheet formed inside the expanding loops. Hot, outgoing plasmoid and post flare loops are formed as a result of the reconnection. Numerical results are consistent with the observed plasma temperature (107 – 108K), the length of the flaring loop (1011 – 1012cm), and the speed of optical jets (200 – 400 km s−1 ).

scholarly journals Trojans in Exosystems with Two Massive Planets

2012 ◽  
Vol 8 (S293) ◽  
pp. 152-158 ◽  
Author(s):  
Rudolf Dvorak ◽  
Li-Yong Zhou ◽  
Helmut Baudisch
Keyword(s):  
Numerical Integration ◽  
Equilibrium Points ◽  
Planetary Systems ◽  
Central Star ◽  
Giant Planets ◽  
Dynamical Model ◽  
Outer Planet ◽  
Mass Ratio ◽  
Wide Range ◽  
Mass Ratios

AbstractWe take as dynamical model for extrasolar planetary systems a central star like our Sun and two giant planets m1 and m2 like Jupiter and Saturn. We change the mass ratio μ=m2/m1 of the two large planets for a wide range of 1/16 < μ < 16. We also change the ratio between the initial semi-major axes (ν=a2/a1) in the range of 1.2 < ν < 3 to model the different architecture of extrasolar planetary systems hosting two giant planets. The results for possible Trojans (Trojan planets) in the equilateral equilibrium points of the inner planet m1 and the outer planet m2 were derived with the aid of numerical integration. It turned out that in many configurations – depending on the mass ratios μ and the semi-major axes ratio ν – giant planets may host Trojans.

scholarly journals Conditions for the appearance of stars with a rotation opposite to the orbital rotation of their planets

2021 ◽  
pp. 22-25
Author(s):  
А.В. Тутуков ◽  
А.В. Федорова
Keyword(s):  
Molecular Clouds ◽  
Planetary System ◽  
Planetary Systems ◽  
Central Star ◽  
Giant Molecular Clouds ◽  
Relative Speed ◽  
Solar Mass ◽  
Orbital Rotation ◽  
Direction Opposite ◽  
Central Stars

Обнаружение планетной системы K2-290 A с двумя копланарными планетами, которые обращаются в направлении, обратном вращению центральной звезды, ставит задачу поиска адекватного сценария возникновения таких систем. В данной статье представленные нами ранее сценарии образования планетных систем пересматриваются для оценки возможности формирования в их рамках планет с орбитальным вращением, обратным вращению их центральных звезд. Оценки показывают, что аккреция холодного газа гигантских молекулярных облаков старыми звездами солнечной массы, движущимися в этих облаках с низкой относительной скоростью менее ∼ 1 км/с - это наиболее вероятный сценарий возникновения таких планетных систем. С другой стороны, обратное вращение только одной из нескольких планет системы может быть результатом взаимодействия близких массивных планет на неустойчивых орбитах. Detection of planetary system K2-290 A with two coplanar planets, which rotate in the direction opposite to the rotation of the central star, poses the problem of finding an adequate scenario for the emergence of such systems. In this article, the scenarios for the formation of planetary systems are revised to assess the possibility of forming within their framework planets with orbital rotation opposite to the rotation of their central stars. Estimates show that the accretion of cold gas from giant molecular clouds (GMOs) by old solar-mass stars moving in GMOs with a relative speed less than ∼ 1 km/s - this is the most probable scenario for the emergence of such planetary systems. On the other hand, the opposite rotation of only one of the several planets of the system can be the result of interaction of nearby massive planets in unstable orbits.

scholarly journals Inner rocky super-Earth formation: distinguishing the formation pathways in viscously heated and passive discs

2019 ◽  
Vol 630 ◽  
pp. A51 ◽  
Author(s):  
Bertram Bitsch
Keyword(s):  
System Architecture ◽  
Rebound Effect ◽  
Planetary Systems ◽  
Central Star ◽  
Ratio Distribution ◽  
Heating Source ◽  
Earth Observations ◽  
Heated Disc ◽  
And Migration ◽  
Final System

Observations have revealed that super-Earths (planets up to 10 Earth masses) are the most abundant type of planets in the inner systems. Their formation is strongly linked to the structure of the protoplanetary disc, which determines growth and migration. In the pebble accretion scenario, planets grow to the pebble isolation mass, at which the planet carves a small gap in the gas disc halting the pebble flux and thus its growth. The pebble isolation mass scales with the disc’s aspect ratio, which directly depends on the heating source of the protoplanetary disc. I compare the growth of super-Earths in viscously heated discs, where viscous heating dissipates within the first million years, and discs purely heated by the central star with super-Earth observations from the Kepler mission. This allows two formation pathways of super-Earths to be distinguished in the inner systems within this framework. Planets growing within 1 Myr in the viscously heated inner disc reach pebble isolation masses that correspond directly to the inferred masses of the Kepler observations for systems that feature planets in resonance or not in resonance. However, to explain the period ratio distribution of Kepler planets – where most Kepler planet pairs are not in mean motion resonance configurations – a fraction of these resonant chains has to be broken. In case the planets are born early in a viscously heated disc, these resonant chains thus have to be broken without planetary mergers, for example through the magnetic rebound effect, and the final system architecture should feature low mutual inclinations. If super-Earths form either late or in purely passive discs, the pebble isolation mass is too small (around 2–3 Earth masses) to explain the Kepler observations, implying that planetary mergers have to play a significant role in determining the final system architecture. Resonant planetary systems thus have to experience mergers already during the gas disc phase, so the planets can get trapped in resonance after reaching 5–10 Earth masses. In case instabilities are dominating the system architecture, the systems should not be flat, but feature mutually inclined orbits. This implies that future observations of planetary systems with radial velocities (RV) and transits (for example through the Transiting Exoplanet Survey Satellite (TESS) and its follow up RV surveys) could distinguish between these two formation channels of super-Earth and thus constrain planet formation theories.

Numerical and experimental study of dynamics of two pendulums under a magnetic field

2019 ◽  
Vol 233 (4) ◽  
pp. 441-453 ◽  
Author(s):  
Krystian Polczyński ◽  
Adam Wijata ◽  
Jan Awrejcewicz ◽  
Grzegorz Wasilewski
Keyword(s):  
Magnetic Field ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Magnetic Interaction ◽  
Variable Magnetic Field ◽  
Phase Portraits ◽  
Bifurcation Diagrams ◽  
Regular Motion ◽  
Novel Model ◽  
Two Degree Of Freedom

In this article, a two-degree-of-freedom system consisting of two pendulums with magnets embedded in a variable magnetic field is investigated experimentally and numerically. Pivots of the pendulums are coupled by an elastic element. The magnetic interaction originates from permanent magnets, mounted at free ends of the pendulums and current-powered air coils underneath. A novel model for the magnetic force is proposed and verified experimentally. Nonlinear dynamics of the system is examined by means of time series, bifurcation diagrams, phase portraits, and Poincaré sections. Regions of chaotic and regular motion are predicted numerically and justified experimentally. Multiperiodic motion and coexisting solutions are detected, and pictures in basins of their attraction are reported, among other.

scholarly journals Planetary Systems and Stellar Multiplicity

1977 ◽  
Vol 33 ◽  
pp. 175-187
Author(s):  
Su-Shu Huang
Keyword(s):  
Planetary System ◽  
Genetic Difference ◽  
Surrounding Medium ◽  
Planetary Systems ◽  
Rotating Disk ◽  
Central Star ◽  
Dust Particles ◽  
Basic Point ◽  
Multiple Systems ◽  
Orbital Periods

AbstractIn this paper we have discussed the origin of planetary systems on one hand and binary and multiple stars on the other. First we show that phenomenological differences between these two kinds of celestial objects are due to their genetic difference. The basic point is that formation of a planetary system around a star has to be a minor event in the life history of the star while formation of a binary or multiple system has to be an event that is important equally to all components of the system. Thus the planetary system evolves from a rotating disk of gaseous and dust particles that comes into being after the star has already been there. It is therefore reasonable to suggest that the rotating disk results from transfer of angular momentum from the central star to the surrounding medium which is likely a residue left over in the process of formation of the central star.Binary and multiple systems cannot be formed in this way because they do not show the characteristics of having come out of a rotating disk. The dominant mechanism of their formation is that they were formed naturally as they are, each from perhaps a single condensation in the interstellar medium. However such a single mechanism of formation cannot satisfactorily explain the observed spread of binaries in mean separations between two components (or equivalently orbital periods). But the disagreement may be removed by including a small number of binaries formed by other processes and by considering the change of orbital elements of binaries after their formation. Trapezia were likely formed also by more than one mechanism.That several stars could be formed, from a single condensation requires the” existence oí pre-stellar nuclei which are briefly: discussed at the end of the paper.

scholarly journals Orbital Motion and Magnetic Activity in Close Binaries and Planetary Systems

2004 ◽  
Vol 219 ◽  
pp. 411-422
Author(s):  
Marcello Rodonò ◽  
Antonino F. Lanza
Keyword(s):  
Orbital Period ◽  
Observational Studies ◽  
Planetary Systems ◽  
Activity Cycle ◽  
Central Star ◽  
Magnetic Activity ◽  
Close Binaries ◽  
Cyclic Behaviour ◽  
Promising Tool ◽  
Cyclic Changes

The connection between orbital period variation and magnetic activity cyclic behaviour in close binaries with late-type components is addressed by discussing recent observational studies of Algols, RS CVn's, W UMa's and CVs. A theoretical model based on the Applegate's mechanism seems capable of explaining the observed orbital period modulation in terms of cyclic changes of a gravitational quadrupole moment induced by a magnetic activity cycle affecting one of the binary components. In such a case, the study of orbital period modulations offers a promising tool to investigate hydromagnetic dynamos operating in the interior of active stars, in particular, to address the fundamental question of the interaction between rotation and magnetic fields in nonlinear dynamo regimes. Moreover, interesting applications to planetary systems with a magnetically active central star are discussed.

scholarly journals Early evolution of the planetary system around PSR B1257+12

2004 ◽  
Vol 202 ◽  
pp. 187-189
Author(s):  
Alexander Gusev ◽  
Irina Kitiashvili
Keyword(s):  
Bifurcation Theory ◽  
Planetary System ◽  
Early Time ◽  
Plane Motion ◽  
Phase Portraits ◽  
Dimensional Parameter ◽  
3 Dimensional ◽  
Resonance Rotation ◽  
Tidal Torques ◽  
Gravitational Capture

For the plane motion we are completely analyzing the differential equations systems of gravitational capture of the exoplanet at the resonance rotation with action of gravitational and tidal torques by qualitative analysis and bifurcation theory of dynamical systems (DS). The separation of 3-dimensional parameter space of dynamical system by bifurcation surfaces is obtained. The gallery of more than thirty phase portraits of gravitational capture extends the known scenario of cosmogonical evolution of the exoplanet on the early time, when the tidal interaction is very important.

scholarly journals Pebbles versus planetesimals: the case of Trappist-1

2019 ◽  
Vol 631 ◽  
pp. A7 ◽  
Author(s):  
G. A. L. Coleman ◽  
A. Leleu ◽  
Y. Alibert ◽  
W. Benz
Keyword(s):  
Water Content ◽  
Initial Conditions ◽  
Planetary Systems ◽  
Central Star ◽  
Low Mass Stars ◽  
Formation Pathway ◽  
Wide Range ◽  
Mass Size ◽  
Low Mass ◽  
Inner Region

We present a study into the formation of planetary systems around low mass stars similar to Trappist-1, through the accretion of either planetesimals or pebbles. The aim is to determine if the currently observed systems around low mass stars could favour one scenario over the other. To determine these differences, we ran numerous N-body simulations, coupled to a thermally evolving viscous 1D disc model, and including prescriptions for planet migration, photoevaporation, and pebble and planetesimal dynamics. We mainly examine the differences between the pebble and planetesimal accretion scenarios, but we also look at the influences of disc mass, size of planetesimals, and the percentage of solids locked up within pebbles. When comparing the resulting planetary systems to Trappist-1, we find that a wide range of initial conditions for both the pebble and planetesimal accretion scenarios can form planetary systems similar to Trappist-1, in terms of planet mass, periods, and resonant configurations. Typically these planets formed exterior to the water iceline and migrated in resonant convoys into the inner region close to the central star. When comparing the planetary systems formed through pebble accretion to those formed through planetesimal accretion, we find a large number of similarities, including average planet masses, eccentricities, inclinations, and period ratios. One major difference between the two scenarios was that of the water content of the planets. When including the effects of ablation and full recycling of the planets’ envelope with the disc, the planets formed through pebble accretion were extremely dry, whilst those formed through planetesimal accretion were extremely wet. If the water content is not fully recycled and instead falls to the planets’ core, or if ablation of the water is neglected, then the planets formed through pebble accretion are extremely wet, similar to those formed through planetesimal accretion. Should the water content of the Trappist-1 planets be determined accurately, this could point to a preferred formation pathway for planetary systems, or to specific physics that may be at play.

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