Related papers: Theoretical Models of Stellar Activity Cycles
In G dwarfs, the surface distribution, coverage and lifetimes of starspots deviate from solar-like patterns as the rotation rate increases. We set up a numerical platform which includes the large-scale rotational and surface flow effects,…
Magnetic braking causes the spin-down of single stars as they evolve on the main sequence. Models of magnetic braking can also explain the evolution of close binary systems, including cataclysmic variables. The well-known period gap in the…
M dwarfs are active stars that exhibit variability in chromospheric emission and photometry at short and long timescales, including long cycles that are related to dynamo processes. This activity also impacts the search for exoplanets…
Understanding the irregular variation of the solar cycle is crucial due to its significant impact on global climates and the heliosphere. Since the polar magnetic field determines the amplitude of the next solar cycle, variations in the…
Strong magnetic fields are observed in a substantial fraction of upper main sequence stars and white dwarfs. Many such stars are observed to exhibit photometric modulations as the magnetic poles rotate in and out of view, which could be a…
The "solar-stellar connection" began as a relatively small field of research focused on understanding the processes that generate magnetic field in stars and which sometimes lead to a cyclic pattern of long-term variability in activity, as…
Stellar activity cycles reveal continuous relaxation and induction of magnetic fields. The activity cycle is typically traced through the observation of cyclic variations in total brightness or Ca H&K emission flux of stars, as well as…
Magnetism is a ubiquitous property of astrophysical plasmas, yet stellar magnetism still remains far from being completely understood. In this review, we describe recent observational and modelling efforts and progress to expand our…
We describe the defining observations of the solar cycle that provide constraints for the dynamo processes operating within the Sun. Specifically, we report on the following topics: historical sunspot numbers and revisions; active region…
Magnetic fields are considered to be key components of massive stars, with a far-reaching impact on their evolution and ultimate fate. A magnetic mechanism was suggested for the collimated explosion of massive stars, relevant for…
Constraining dynamo theories of magnetic field origin by observation is indispensable but challenging, in part because the basic quantities measured by observers and predicted by modelers are different. We clarify these differences and…
Our understanding of the structure and dynamics of stellar coronae has changed dramatically with the availability of surface maps of both star spots and also magnetic field vectors. Magnetic field extrapolations from these surface maps…
After a brief recall of the main impacts of stellar rotation on the structure and the evolution of stars, four topics are addressed: 1) the links between magnetic fields and rotation; 2) the impact of rotation on the age determination of…
For Sun-like stars, the generation of toroidal magnetic field from poloidal magnetic field is an essential piece of the dynamo mechanism powering their magnetism. Previous authors have estimated the net toroidal flux generated in each…
Increasing evidence is becoming available about not only the surface differential rotation of rapidly rotating cool stars but, in a small number of cases, also about temporal variations, which possibly are analogous to the solar torsional…
Magnetic fields on hot stars can produce a variety of interesting effects on the velocity, density, and temperature structure in the winds from the stars. The fields can produce a longitudinal dependence of the mass flux, which would lead…
Apparent variability of the longitudinal magnetic fields in most stars is caused by rotation, which quantitavely changes projection of the magnetic field configuration on the line of sight. This is a purely geometrical effect and is not…
Existing upper limits on variations in the photospheric radius of the Sun during the solar magnetic activity cycle are at a fractional amplitude of 2x10^{-4}. At that level, the transit duration of a close-in planet around a Sun-like star…
A review on current theories and observations of high-mass star formation is given. Particularly the influence of magnetic fields and feedback mechanisms, and of varying initial conditions on theories are discussed. The, in my biased view,…
We present the results of a study of the stellar activity in the solar neighborhood using complete kinematics (galactocentric velocities U,V,W) and the chromospheric activity index $\log R'_{\rm{HK}}$. We analyzed the average activity level…