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Stellar magnetic dynamos are driven by rotation, rapidly rotating stars produce stronger magnetic fields than slowly rotating stars do. The Zeeman effect is the most important indicator of magnetic fields, but Zeeman broadening must be…

Solar and Stellar Astrophysics · Physics 2015-06-17 Ansgar Reiners

Today, the generation of magnetic fields in solar-type stars and its relation to activity and rotation can coherently be explained, although it is certainly not understood in its entirety. Rotation facilitates the generation of magnetic…

Astrophysics · Physics 2009-11-13 A. Reiners , A. Scholz , J. Eislöffel , G. Hallinan , E. Berger , M. Browning , J. Irwin , M. Küker , S. Matt

We further develop the Tayler--Spruit dynamo theory, based on the most efficient instability for generating magnetic fields in radiative layers of differentially rotating stars. We avoid the simplifying assumptions that either the $\mu$--…

Astrophysics · Physics 2009-11-10 Andre Maeder , Georges Meynet

Cool stars like the Sun harbor convection zones capable of producing substantial surface magnetic fields leading to stellar magnetic activity. The influence of stellar parameters like rotation, radius, and age on cool-star magnetism, and…

Solar and Stellar Astrophysics · Physics 2015-06-04 Ansgar Reiners

Magnetars are neutron stars in which a strong magnetic field is the main energy source. About two dozens of magnetars, plus several candidates, are currently known in our Galaxy and in the Magellanic Clouds. They appear as highly variable…

High Energy Astrophysical Phenomena · Physics 2015-06-24 Sandro Mereghetti , Jose' Pons , Andrew Melatos

We review the measurements of magnetic fields of OBA stars. Based on these data we confirm that magnetic fields are distributed according to a lognormal law with a mean log(B)=-0.5 (B in kG) with a standard deviation sigma=0.5. The shape of…

To properly understand the physics of Ap and Bp stars it is particularly important to identify the origin of their magnetic fields. For that, an accurate knowledge of the evolutionary state of stars that have a measured magnetic field is an…

Astrophysics · Physics 2009-11-11 S. Hubrig , P. North , M. Schoeller , G. Mathys

Magnetic fields represent a crucial aspect of the physics and astrophysics of neutron stars. Despite its great relevance, the internal magnetic field configuration of neutron stars is very poorly constrained by the observations, and…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Riccardo Ciolfi

Rotation and magnetism are increasingly recognized as important phenomena in stellar evolution. Surface magnetic fields from a few to $20{,}000\,$G have been observed and models have suggested that magnetohydrodynamic transport of angular…

Solar and Stellar Astrophysics · Physics 2018-04-04 Leo G. Quentin , Christopher A. Tout

I will show that Be stars are, without exception, a class of rapidly rotating stars, which are in the majority of cases pulsating stars as well, while none of them does possess a large scale (i.e. with significant dipolar contribution)…

Solar and Stellar Astrophysics · Physics 2015-06-11 Th. Rivinius

Compact relativistic stars allow us to study the nature of matter under extreme conditions, probing regions of parameter space that are otherwise inaccessible. Nuclear theory in this regime is not well constrained: one key issue is whether…

Astrophysics · Physics 2008-11-26 Anna L. Watts , Sanjay Reddy

The evolution of magnetic fields in Ap stars during the main sequence phase is presently mostly unconstrained by observation because of the difficulty of assigning accurate ages to known field Ap stars. We are carrying out a large survey of…

Astrophysics · Physics 2015-05-13 J. D. Landstreet , S. Bagnulo , V. Andretta , L. Fossati , E. Mason , J. Silaj , G. A. Wade

Most of the visible matter in the Universe is ionized, so that cosmic magnetic fields are quite easy to generate and due to the lack of magnetic monopoles hard to destroy. Magnetic fields have been measured in or around practically all…

Astrophysics of Galaxies · Physics 2023-10-06 Rainer Beck , Richard Wielebinski

We study the problem of neutron star composition in the presence of a strong magnetic field. The effects of the anomalous magnetic moments of both nucleons and electrons are investigated in relativistic mean field calculations for a…

Astrophysics · Physics 2009-11-07 G. Mao , V. N. Kondratyev , A. Iwamoto , Z. Li , X. Wu , W. Greiner , I. N. Mikhailov

The recent measurement by Bignami and co-workers of the magnetic field of a neutron star for the first time gives a value that differs by about two orders of magnitude from the expected value. The speculation has been that the nuclear…

General Physics · Physics 2007-05-23 B. G. Sidharth

The magnetic field is a key ingredient in the recipe of star formation. Over the past two decades, millimeter and submillimeter interferometers have made major strides in unveiling the role of the magnetic field in star formation at…

Solar and Stellar Astrophysics · Physics 2019-03-11 Charles L. H. Hull , Qizhou Zhang

We present a review of observations of the stellar longitudinal (effective) magnetic field ($B_e$) and its properties. This paper also discusses contemporary views on the origin, evolution and structure of $B_e$.

Solar and Stellar Astrophysics · Physics 2013-10-17 V. D. Bychkov , L. V. Bychkova , J. Madej

I argue that the presence of magnetic fields around evolved stars, e.g., asymptotic giant branch stars, and in PNe, does not necessarily imply that the magnetic field plays a global dynamical role in shaping the circumstellar envelope.…

Astrophysics · Physics 2009-11-07 Noam Soker

Weak magnetic fields have recently been detected in Vega and Sirius. Here, we explore the possibility that these fields are the remnants of some field inherited or created during or shortly after star formation and, unlike true fossil…

Solar and Stellar Astrophysics · Physics 2015-06-03 Jonathan Braithwaite , Matteo Cantiello

To understand the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment, within the MiMeS project, we searched for magnetic objects among a large…