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This article is intended for undergraduate students with the aim to provide a pedagogical introduction to the physics of stellar tidal deformations. The spherically symmetric shape of any star is deformed via rotation around an arbitrary…

High Energy Astrophysical Phenomena · Physics 2020-07-02 Andreas Zacchi

Magneto-elastic oscillations of neutron stars are believed to explain observed quasi-periodic oscillations (QPOs) in the decaying tail of the giant flares of highly magnetized neutron stars (magnetars). Strong efforts of the theoretical…

High Energy Astrophysical Phenomena · Physics 2018-01-10 Michael Gabler , Pablo Cerdá-Durán , Alexei Mate , Nikolaos Stergioulas , José A. Font , Ewald Müller

Recent period investigations of the Post-Common Envelop Binary (PCEB) NSVS 14256825 suggested that two circumbinary companions were necessary to explain the observed Eclipse Timing Variations (ETVs). Our objective was to search for the…

Solar and Stellar Astrophysics · Physics 2024-11-06 Konstantinos Zervas , Panagiota-Eleftheria Christopoulou

Quasi-biennial oscillations (QBO) are frequently observed in the solar activity indices. However, no clear physical mechanism for the observed variations has been suggested so far. Here we study the stability of magnetic Rossby waves in the…

Solar and Stellar Astrophysics · Physics 2015-05-20 T. V. Zaqarashvili , M. carbonell , R. Oliver , J. L. Ballester

We find numerical solutions of the coupled system of Einstein-Maxwell's equations with a linear approach, in which the magnetic field acts as a perturbation of a spherical neutron star. In our study, magnetic fields having both poloidal and…

Astrophysics · Physics 2009-11-13 A. Colaiuda , V. Ferrari , L. Gualtieri , J. A. Pons

Weak magnetic fields have recently been detected in a number of A-type stars, including Vega and Sirius. At the same time, space photometry observations of A- and late B-type stars from Kepler and TESS have highlighted the existence of…

Solar and Stellar Astrophysics · Physics 2019-10-02 Matteo Cantiello , Jonathan Braithwaite

The origin of interstellar and intergalactic magnetic fields remains largely unknown. One possibility is that they are related to the primordial magnetic fields (PMFs) produced by, for instance, the phase transitions of the early Universe.…

High Energy Astrophysical Phenomena · Physics 2024-03-05 Yao-Yu Li , Chi Zhang , Ziwei Wang , Ming-Yang Cui , Yue-Lin Sming Tsai , Qiang Yuan , Yi-Zhong Fan

Spacecraft data reveal a very Earth-like Jovian magnetic field. This is surprising since numerical simulations have shown that the vastly different interiors of terrestrial and gas planets can strongly affect the internal dynamo process.…

Earth and Planetary Astrophysics · Physics 2015-06-22 T. Gastine , J. Wicht , L. Duarte , M. Heimpel , A. Becker

We present a new mechanism for oscillatory or random reversals of the magnetic field that occur from a stationary dynamo state. The basic ingredient is the existence of two nearly critical dynamo eigenmodes, a stable and an unstable one,…

Geophysics · Physics 2008-10-29 F. Petrelis , S. Fauve

Six decades and counting, the formation of hot ~20,000-30,000 K Extreme Horizontal Branch (EHB) stars in Galactic Globular Clusters remains one of the most elusive quests in stellar evolutionary theory. Here we report on two discoveries…

Spider millisecond pulsars are, along with some eclipsing post-common envelope systems and cataclysmic variables, part of an expanding category of compact binaries with low-mass companions for which puzzling timing anomalies have been…

High Energy Astrophysical Phenomena · Physics 2019-12-10 Guillaume Voisin , René Breton , Charlotte Summers

Transition region explosive events have long been suggested as direct signatures of magnetic reconnection in the solar atmosphere. In seeking further observational evidence to support this interpretation, we study the relation between…

Astrophysics · Physics 2009-11-13 K. Muglach

This paper reviews the rich corpus of observational evidence for tidal effects in short-period binaries. We review the evidence for ellipsoidal variability and for the observational manifestation of apsidal motion in eclipsing binaries.…

Astrophysics · Physics 2009-11-13 Tsevi Mazeh

Recent observations indicate that kinetic and magnetic energies are not in equipartition in the solar wind turbulence. Rather, magnetic fluctuations are more energetic and have somewhat steeper energy spectrum compared to the velocity…

Astrophysics of Galaxies · Physics 2015-05-30 Stanislav Boldyrev , Jean Carlos Perez , Vladimir Zhdankin

We perform the first magnetohydrodynamical simulations of tidal disruptions of stars by supermassive black holes. We consider stars with both tangled and ordered magnetic fields, for both grazing and deeply disruptive encounters. When the…

High Energy Astrophysical Phenomena · Physics 2017-01-18 James Guillochon , Michael McCourt

Observations of chromospheric and coronal emissions from various solar-type stars show that the stellar magnetic activity varies with the rotation rates of the stars. The faster the star rotates, its magnetic activity gets stronger but…

Solar and Stellar Astrophysics · Physics 2019-10-16 Gopal Hazra , Jie Jiang , Bidya Binay Karak , Leonid Kitchatinov

It is shown that depletion of the magnetic field pressure in a quaking neutron star undergoing Lorentz-force-driven torsional seismic vibrations about axis of its dipole magnetic moment is accompanied by the loss of vibration energy of the…

High Energy Astrophysical Phenomena · Physics 2010-09-07 S. I. Bastrukov , I. V. Molodtsova , J. W. Yu , R. X. Xu

We present new wind models for {\tau} Bo\"otis ({\tau} Boo), a hot-Jupiter-host-star whose observable magnetic cycles makes it a uniquely useful target for our goal of monitoring the temporal variability of stellar winds and their…

Solar and Stellar Astrophysics · Physics 2016-11-15 B. A. Nicholson , A. A. Vidotto , M. Mengel , L. Brookshaw , B. Carter , P. Petit , S. C. Marsden , S. V. Jeffers , R. Fares , the BCool Collaboration

We expand on our study of the gravitational and electromagnetic emissions from the late stage of an inspiraling neutron star binary as presented in Ref. \cite{Palenzuela:2013hu}. Interactions between the stellar magnetospheres, driven by…

General Relativity and Quantum Cosmology · Physics 2013-09-13 Carlos Palenzuela , Luis Lehner , Steven L. Liebling , Marcelo Ponce , Matthew Anderson , David Neilsen , Patrick Motl

We couple internal torsional, magneto-elastic oscillations of highly magnetized neutron stars (magnetars) to their magnetospheres. The corresponding axisymmetric perturbations of the external magnetic field configuration evolve as a…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Michael Gabler , Pablo Cerdá-Durán , Nikolaos Stergioulas , José A. Font , Ewald Müller