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In dynamical systems of few degrees of freedom, periodic solutions consist the backbone of the phase space and the determination and computation of their stability is crucial for understanding the global dynamics. In this paper we study the…

Earth and Planetary Astrophysics · Physics 2014-07-29 Kyriaki I. Antoniadou , George Voyatzis , Harry Varvoglis

The main purpose of this work is to provide a non-local approach to study aspects of structural stability of 3D Filippov systems. We introduce a notion of semi-local structural stability which detects when a piecewise smooth vector field is…

Dynamical Systems · Mathematics 2017-08-22 Otávio M. L. Gomide , Marco A. Teixeira

The paper shows an inf-sup stability property for several well-known 2D and 3D Stokes elements on triangulations which are not fitted to a given smooth or polygonal domain. The property implies stability and optimal error estimates for a…

Numerical Analysis · Mathematics 2017-04-24 Johnny Guzmán , Maxim Olshanskii

We measure the 3D kinematic structures of the young stars within the central 0.5 parsec of our Galactic Center using the 10 m telescopes of the W.~M.~Keck Observatory over a time span of 25 years. Using high-precision measurements of…

We prove new global stability estimates for the Gel'fand-Calderon inverse problem in 3D. For sufficiently regular potentials this result of the present work is a principal improvement of the result of [G. Alessandrini, Stable determination…

Analysis of PDEs · Mathematics 2011-03-03 Roman Novikov

Through an extensive set of realistic synthetic observations (produced in Paper I), we assess in this part of the paper series (Paper III) how the choice of observational techniques affects the measurement of star-formation rates (SFRs) in…

Solar and Stellar Astrophysics · Physics 2017-11-01 Christine M. Koepferl , Thomas P. Robitaille , James E. Dale

Active Galactic Nuclei (AGNs), owing to their great distances and compact sizes, serve as fundamental anchors for defining the celestial reference frame. With about 1.9 million AGNs observed in Gaia DR3 at optical precision comparable to…

Astrophysics of Galaxies · Physics 2025-11-05 Shilong Liao , Qiqi Wu , Ye Ding , Qi Xu , Zhaoxiang Qi

The diffraction contrast modalities accessible by X-ray grating interferometers are not imaged directly but have to be inferred from sine like signal variations occurring in a series of images acquired at varying relative positions of the…

Instrumentation and Detectors · Physics 2021-02-01 Jonas Dittmann , Andreas Balles , Simon Zabler

Cosmic ray (CR)-driven instabilities play a decisive role during particle acceleration at shocks and CR propagation in galaxies and galaxy clusters. These instabilities amplify magnetic fields and modulate CR transport so that the…

High Energy Astrophysical Phenomena · Physics 2021-03-03 Mohamad Shalaby , Timon Thomas , Christoph Pfrommer

This paper investigates the long-term orbital stability of small bodies near the central binary of the Alpha Centauri system. Test particles on circular orbits are integrated in the field of this binary for 32000 binary periods or…

Astrophysics · Physics 2009-10-28 Paul A. Wiegert , Matt Holman

We present two approaches to determine the dynamical stability of a hierarchical triple-star system. The first is an improvement on the Mardling-Aarseth stability formula from 2001, where we introduce a dependence on inner orbital…

Solar and Stellar Astrophysics · Physics 2022-09-14 Pavan Vynatheya , Adrian S. Hamers , Rosemary A. Mardling , Earl P. Bellinger

Using zoom-simulations carried out with the adaptive mesh-refinement code RAMSES with a dynamic range of up to $2^{27} \approx 1.34 \times 10^8$ we investigate the accretion profiles around six stars embedded in different environments…

Solar and Stellar Astrophysics · Physics 2018-02-01 Michael Kuffmeier , Søren Frimann , Sigurd S. Jensen , Troels Haugbølle

The Gaia optical reference frame is intrinsically undefined with respect to global orientation and spin, so it needs to be anchored in the radio-based International Celestial Reference Frame (ICRF) to provide a referenced and quasi-inertial…

Instrumentation and Methods for Astrophysics · Physics 2021-06-09 Valeri V. Makarov

Surface photometry from 16 HST/WFPC2 fields in the I(F814W) filter is used to derive the distribution of apparent axis ratios for galaxies in progressively fainter magnitude intervals for I<25. We assess the systematic and accidental errors…

Astrophysics · Physics 2009-10-30 S. C. Odewahn , D. Burstein , R. A. Windhorst

We report optical and X-ray observations of the high-field polar RXJ1007.5-2017 performed between 1990 and 2012. It has an orbital period of 208.60 min determined from the ellipsoidal modulation of the secondary star in an extended low…

High Energy Astrophysical Phenomena · Physics 2015-06-11 H. -C. Thomas , K. Beuermann , K. Reinsch , A. D. Schwope , V. Burwitz

In this work feedback control laws are designed for achieving three-axis attitude stabilization of inertial pointing spacecraft using only magnetic torquers. The designs are based on an almost periodic model of geomagnetic field along the…

Optimization and Control · Mathematics 2015-06-23 Fabio Celani

Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-$J$ geometry) are…

Plasma Physics · Physics 2015-06-17 J. H. E. Proll , P. Xanthopoulos , P. Helander

This paper investigates the dynamics of closed vortex filaments in $\R^3$ governed by the Localized Induction Equation. Recently, Aiki and Higaki (2026) established the nonlinear orbital stability of circular vortex filaments under…

Analysis of PDEs · Mathematics 2026-04-20 Masashi Aiki , Mitsuo Higaki

We develop a new approach and employ it to establish the global existence and nonlinear structural stability of attached weak transonic shocks in steady potential flow past three-dimensional wedges; in particular, the restriction that the…

Analysis of PDEs · Mathematics 2021-08-10 Gui-Qiang G. Chen , Jun Chen , Wei Xiang

We present the first results of the observations of the X-ray pulsars LMC X-4, 4U0352+309 and EXO1722-363 performed with the INTEGRAL observatory. The LMC X-4 was investigated during the whole superorbital cycle ($\sim$30 days) and it was…

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