Related papers: Solar-like Oscillations: An Observational Perspect…
We recently reported strong evidence for solar-like oscillations in the G0 IV star eta Boo (Kjeldsen et al. 1995, AJ 109, 1313). We measured small temperature fluctuations produced by oscillations through their effect on the equivalent…
Spectral-line displacements away from the wavelengths naively expected from the Doppler shift caused by stellar radial motion may originate as convective shifts (correlated velocity and brightness patterns in the photosphere), as…
Surface convection is important for the presence of magnetic activity at stars. So far, this convection is thought to be a result of heating from below, where convection cells rise and break up. New models reveal that surface convection is…
The Sun and solar-type stars exhibit irregular cyclic variations in their magnetic activity over long time scales. To understand this irregularity, we employed the flux transport dynamo models to investigate the behavior of one solar mass…
When stars depart from the main-sequence, various changes occur including the loss of angular momentum owing to changes in the stellar interior and the impact of stellar winds. These processes affect the amount of outer atmospheric heating…
Using data from the Global Oscillations Network Group (GONG) that covers the period from 1995 to 1998 we study the change in frequencies of solar oscillations with solar activity. From these frequencies we attempt to determine any possible…
Successful inference from asteroseismology relies on at least two things: that the oscillations in the stars have amplitudes large enough to be clearly observable; and that the oscillations themselves be stable enough to enable precise…
Torsional oscillations represent bands of fast and slow zonal flows around the Sun, which extend deep into the convection zone and migrate during solar cycles towards the equator following the sunspot butterfly diagram. Analysis of…
We present the results of three-dimensional simulations of the deep convective envelope of a young (10 Myr) one-solar-mass star, obtained with the Anelastic Spherical Harmonic code. Since young stars are known to be faster rotators than…
The Sun's rotation profile and lithium content have been difficult to understand in the context of conventional models of stellar evolution. Classical hydrodynamical models predict that the solar interior must rotate highly differentially,…
Over the last two decades the uninterrupted, high-resolution observations of the Sun, from the excellent range of telescopes aboard many spacecraft complemented with observations from sophisticated ground-based telescopes have opened up a…
By extending our self-consistent MHD simulations for the solar wind, we study the evolution of stellar winds of solar-type stars from early main sequence stage to red giant phase. Young solar-type stars are active and the mass loss rates…
Spectroscopic observations at extreme and far ultraviolet wavelengths have revealed systematic upflows in the solar transition region and corona. These upflows are best seen in the network structures of the quiet Sun and coronal holes,…
Acoustic power and oscillation amplitudes of radial oscillations computed for a solar model are compared with solar seismic observations. The oscillations are assumed stochastically excited by turbulence. The numerical computations are…
Sudden changes in the internal structure of stars, placed at the interface between convective and radiative regions, regions of partial ionisation, or between layers that have acquired different chemical composition as a result of nuclear…
Velocity measurements of the G2 subgiant beta Hyi with both UCLES and CORALIE show a clear excess of power centred at 1.0 mHz. In the UCLES data we find evidence for a short-lived, high-amplitude oscillation event. If confirmed as a feature…
Solar oscillations are expected to be excited by turbulent flows in the intergranular lanes near the solar surface. Time series recorded by the IMaX instrument aboard the {\sc Sunrise} observatory reveal solar oscillations at high…
We discuss properties and examples of r-mode (large scale Rossby wave) oscillations in rotating stars. Motions are nearly toroidal but affected weakly by buoyancy. R modes seem to be excited mechanically in most cases, and ubiquitous in…
Red Giant stars host solar-like oscillations which have mixed character, being sensitive to conditions both in the outer convection zone and deep within the interior. The properties of these modes are sensitive to both core rotation and…
The atmospheric activity of the Sun and solar-type stars is analysed involving observations from HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Observatories, and the…