Understanding Skyrmion Crystal Formation in EuPtSi

2021 ◽  
Vol 1 ◽  
Keyword(s):  
Field Direction ◽  
Crystal Formation ◽  
Spin Orbit ◽  
Short Period

We theoretically demonstrate that the interplay between the spin-charge and spin-orbit couplings in itinerant magnets stabilizes field-direction sensitive, short-period skyrmions. Our results can aid in engineering short-period skyrmions.

scholarly journals On the secondary’s rotation in a synchronous binary asteroid

2020 ◽  
Vol 493 (1) ◽  
pp. 171-183
Author(s):  
H S Wang ◽  
X Y Hou
Keyword(s):  
Periodic Orbits ◽  
Body Problem ◽  
Spin Orbit ◽  
Binary Asteroid ◽  
Classical Spin ◽  
Long Period ◽  
Period Orbit ◽  
Short Period ◽  
Orbit Eccentricity ◽  
Binary Asteroid System

ABSTRACT This article studies the secondary’s rotation in a synchronous binary asteroid system in which the secondary enters the 1:1 spin-orbit resonance. The model used is the planar full two-body problem, composed of a spherical primary plus a triaxial ellipsoid secondary. Compared with classical spin-orbit work, there are two differences: (1) influence of the secondary’s rotation on the mutual orbit is considered and (2) instead of the Hamiltonian approach, the approach of periodic orbits is adopted. Our studies find the following. (1) The genealogy of the two families of periodic orbits is the same as that of the families around triangular libration points in the restricted three-body problem. That is, the long-period family terminates on to a short-period orbit travelling N times. (2) In the limiting case where the secondary’s mass is negligible, our results can be reduced to classical spin-orbit theory, by equating the long-period orbit with free libration and the short-period orbit with the forced libration caused by orbit eccentricity. However, the two models show obvious differences when the secondary’s mass is non-negligible. (3) By studying the stability of periodic orbits for a specific binary asteroid system, we are able to obtain the maximum libration amplitude of the secondary (which is usually less than 90°) and the maximum mutual orbit eccentricity that does not break the secondary’s synchronous state. We also find an anti-correlation between the secondary’s libration amplitude and the orbit eccentricity. The (65803) Didymos system is taken as an example to show the results.

scholarly journals The EBLM project – VII. Spin–orbit alignment for the circumbinary planet host EBLM J0608-59 A/TOI-1338 A

2020 ◽  
Vol 497 (2) ◽  
pp. 1627-1633 ◽  
Author(s):  
Vedad Kunovac Hodžić ◽  
Amaury H M J Triaud ◽  
David V Martin ◽  
Daniel C Fabrycky ◽  
Heather M Cegla ◽  
...  
Keyword(s):  
Rotation Period ◽  
Primary Component ◽  
High Resolution Spectroscopy ◽  
Spin Orbit ◽  
Primary Star ◽  
Secondary Star ◽  
Short Period ◽  
Low Mass ◽  
Detached Binaries ◽  
Binary Orbit

ABSTRACT A dozen short-period detached binaries are known to host transiting circumbinary planets. In all circumbinary systems so far, the planetary and binary orbits are aligned within a couple of degrees. However, the obliquity of the primary star, which is an important tracer of their formation, evolution, and tidal history, has only been measured in one circumbinary system until now. EBLM J0608-59/TOI-1338 is a low-mass eclipsing binary system with a recently discovered circumbinary planet identified by TESS. Here, we perform high-resolution spectroscopy during primary eclipse to measure the projected stellar obliquity of the primary component. The obliquity is low, and thus the primary star is aligned with the binary and planetary orbits with a projected spin–orbit angle β = 2${_{.}^{\circ}}$8 ± 17${_{.}^{\circ}}$1. The rotation period of 18.1 ± 1.6 d implied by our measurement of vsin i⋆ suggests that the primary has not yet pseudo-synchronized with the binary orbit, but is consistent with gyrochronology and weak tidal interaction with the binary companion. Our result, combined with the known coplanarity of the binary and planet orbits, is suggestive of formation from a single disc. Finally, we considered whether the spectrum of the faint secondary star could affect our measurements. We show through simulations that the effect is negligible for our system, but can lead to strong biases in vsin i⋆ and β for higher flux ratios. We encourage future studies in eclipse spectroscopy test the assumption of a dark secondary for flux ratios ≳1 ppt.

scholarly journals Effects of magnetic braking and tidal friction on hot Jupiters

2008 ◽  
Vol 4 (S259) ◽  
pp. 295-302
Author(s):  
Adrian J. Barker ◽  
Gordon I. Ogilvie
Keyword(s):  
Evolution Equations ◽  
Phase Plane Analysis ◽  
Spin Orbit ◽  
Tidal Evolution ◽  
Tidal Friction ◽  
Hot Jupiters ◽  
Secular Evolution ◽  
Orbit Evolution ◽  
Short Period ◽  
Magnetic Braking

AbstractTidal friction is thought to be important in determining the long-term spin-orbit evolution of short-period extrasolar planetary systems. Using a simple model of the orbit-averaged effects of tidal friction (Eggleton et al. 1998), we analyse the effects of the inclusion of stellar magnetic braking on the evolution of such systems. A phase-plane analysis of a simplified system of equations, including only the stellar tide together with a model of the braking torque proposed by Verbunt & Zwaan (1981), is presented. The inclusion of stellar magnetic braking is found to be extremely important in determining the secular evolution of such systems, and its neglect results in a very different orbital history. We then show the results of numerical integrations of the full tidal evolution equations, using the misaligned spin and orbit of the XO-3 system as an example, to study the accuracy of simple timescale estimates of tidal evolution. We find that it is essential to consider coupled evolution of the orbit and the stellar spin in order to model the behaviour accurately. In addition, we find that for typical Hot Jupiters the stellar spin-orbit alignment timescale is of the same order as the inspiral time, which tells us that if a planet is observed to be aligned, then it probably formed coplanar. This reinforces the importance of Rossiter-McLaughlin effect observations in determining the degree of spin-orbit alignment in transiting systems.

Shell regeneration in Helix: shell matrix composition and crystal formation

1969 ◽  
Vol 47 (6) ◽  
pp. 1107-1111 ◽  
Author(s):  
A. S. M. Saleuddin ◽  
Wilson Chan
Keyword(s):  
Chemical Nature ◽  
Early Stage ◽  
Organic Matrix ◽  
Matrix Composition ◽  
Crystal Formation ◽  
Shell Matrix ◽  
Nucleation Sites ◽  
Small Crystals ◽  
Short Period ◽  
Shell Regeneration

The chemical nature of the electron-dense areas appearing on the organic matrix during the early stage of shell regeneration in Helix has been ascertained. These areas of 500–5000 Å are made up mainly of acid mucopolysaccharides as detected by thorium staining. When treated by 1% phosphotungstic acid (PTA) for a short period, these electron-dense areas took up the stain, suggesting the presence of mucoprotein and glycoproteins, and are probably the nucleation sites for calcification because small crystals of CaCO3 appear with them. The small crystals join to form larger ones. Crystals grow presumably by dendritic growth, and eventually form a calcified layer. Electron diffraction studies on these crystals show the presence of aragonite (type present in the normal shell) and calcite.

scholarly journals Preparations for inhibiting crystal formation in wine

2020 ◽  
pp. 168-173
Author(s):  
София Николаевна Червяк ◽  
Нонна Владимировна Гниломедова ◽  
Антонина Валерьевна Весютова ◽  
Ольга Алексеевна Чурсина
Keyword(s):  
Inhibitory Effect ◽  
Maximum Effect ◽  
Crystal Formation ◽  
Red Wines ◽  
Protective Properties ◽  
Arabic Gum ◽  
Short Period ◽  
Crystallization Center ◽  
Phenolic Substances ◽  
Molecular Substances

Потеря растворимости виннокислых солей калия и кальция является причиной выпадения кристаллического осадка в вине. Одним из способов стабилизации вин является внесение высокомолекулярных веществ в готовый к розливу продукт. Коллоидные вещества не препятствуют образованию ядер кристаллизации битартрата калия, но обладают ингибирующим действием по отношению к росту кристаллов. В то же время предлагаемые вещества имеют особенности, которые необходимо учитывать при выборе схемы обработки: метавинная кислота эффективна для всех типов вин, однако сохраняет свои свойства непродолжительное время; КМЦ наибольшее действие проявляет в белых винах, при этом может спровоцировать выпадение фенольных веществ в красных винах; маннопротеины не отличаются стабильным результатом. Гуммиарабик проявляет протекторные свойства не только в отношении фенольных веществ, но и эффективно блокирует рост кристаллов битартрата калия. Защитное действие гуммиарабика и полиаспартата калия недостаточно освещено в научной литературе, что обусловливает необходимость дальнейших исследований в экспериментальных и производственных условиях. Loss of solubility of tartaric salts of potassium and calcium is the cause of precipitation of crystal sediment in wine. One of the ways to stabilize wines is to introduce high-molecular substances into the product ready for bottling. Colloidal substances do not prevent the formation of crystallization center of potassium bitartrate, but possess an inhibitory effect on the growth of crystals. At the same time, the proposed substances offer properties that must be taken into account when choosing a treatment scheme: metatartaric acid is effective for all types of wines, but retains its properties for a short period of time; CMC demonstrates maximum effect in white wines, while it can provoke the sedimentation of phenolic substances in red wines; mannoproteins do not show steady result. Arabic gum shows protective properties not only in relation to phenolic substances, but also effectively blocks the growth of potassium bitartrate crystals. The protective effect of arabic gum and potassium polyaspartate is not sufficiently covered in the scientific literature, which necessitates further research in experimental and industrial conditions.

scholarly journals Nonlinear tidal flows in short-period planets

2019 ◽  
Vol 82 ◽  
pp. 43-50
Author(s):  
A.J. Barker
Keyword(s):  
Extrasolar Planets ◽  
Spin Orbit ◽  
Tidal Evolution ◽  
Tidal Dissipation ◽  
Hot Jupiters ◽  
Fluid Instability ◽  
Short Period ◽  
Elliptical Instability ◽  
Turbulent Damping ◽  
Tidal Deformations

I discuss two related nonlinear mechanisms of tidal dissipation that require finite tidal deformations for their operation: the elliptical instability and the precessional instability. Both are likely to be important for the tidal evolution of short-period extrasolar planets. The elliptical instability is a fluid instability of elliptical streamlines, such as in tidally deformed non-synchronously rotating or non-circularly orbiting planets. I summarise the results of local and global simulations that indicate this mechanism to be important for tidal spin synchronisation, planetary spin-orbit alignment and orbital circularisation for the shortest period hot Jupiters. The precessional instability is a fluid instability that occurs in planets undergoing axial precession, such as those with spin-orbit misalignments (non-zero obliquities). I summarise the outcome of local MHD simulations designed to study the turbulent damping of axial precession, which suggest this mechanism to be important in driving tidal evolution of the spin-orbit angle for hot Jupiters. Avenues for future work are also discussed.

scholarly journals Spin‐Orbit Evolution of Short‐Period Planets

2004 ◽  
Vol 610 (1) ◽  
pp. 464-476 ◽  
Author(s):  
Ian Dobbs‐Dixon ◽  
D. N. C. Lin ◽  
Rosemary A. Mardling
Keyword(s):  
Spin Orbit ◽  
Orbit Evolution ◽  
Short Period

scholarly journals Evolution of spin direction of accreting magnetic protostars and spin-orbit misalignment in exoplanetary systems

2010 ◽  
Vol 6 (S276) ◽  
pp. 295-299
Author(s):  
Dong Lai ◽  
Francois Foucart ◽  
Douglas N. C. Lin
Keyword(s):  
Spin Axis ◽  
Magnetic Star ◽  
Spin Orbit ◽  
Tidal Interactions ◽  
Rotation Axes ◽  
Exoplanetary Systems ◽  
Short Period ◽  
Protostellar Discs ◽  
Orbital Axis ◽  
Parent Star

AbstractRecent observations have shown that in many exoplanetary systems the spin axis of the parent star is misaligned with the planet's orbital axis. These have been used to argue against the scenario that short-period planets migrated to their present-day locations due to tidal interactions with their natal discs. However, this interpretation is based on the assumption that the spins of young stars are parallel to the rotation axes of protostellar discs around them. We show that the interaction between a magnetic star and its circumstellar disc can (although not always) have the effect of pushing the stellar spin axis away from the disc angular momentum axis toward the perpendicular state and even the retrograde state. Planets formed in the disc may therefore have their orbital axes misaligned with the stellar spin axis, even before any additional planet-planet scatterings or Kozai interactions take place. In general, magnetosphere–disc interactions lead to a broad distribution of the spin–orbit angles, with some systems aligned and other systems misaligned.

scholarly journals Tidal evolution of star-planet systems

2010 ◽  
Vol 6 (S276) ◽  
pp. 238-242
Author(s):  
Rosemary A. Mardling
Keyword(s):  
Binary Star ◽  
Spin Orbit ◽  
Tidal Evolution ◽  
Tide Model ◽  
Orbital Decay ◽  
Short Period

AbstractThe equilibrium tide model in the weak friction approximation is used by the binary star and exoplanet communities to study the tidal evolution of short-period systems, however, each uses a slightly different approach which potentially leads to different conclusions about the timescales on which various processes occur. Here we present an overview of these two approaches, and show that for short-period planets the circularization timescales they predict differ by at most a factor of a few. A discussion of the timescales for orbital decay, spin-orbit synchronization and spin-orbit alignment is also presented.

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