Related papers: Minuscule corrections to near-surface solar intern…
Models of solar-like oscillators yield acoustic modes at different frequencies than would be seen in actual stars possessing identical interior structure, due to modelling error near the surface. This asteroseismic "surface term" must be…
Although the interplanetary magnetic field variability has been extensively investigated in situ by means of data coming from several space missions, the newly launched missions providing high-resolution measures and approaching the Sun,…
In this article, we derive and compute the sensitivity of measurements of coupling between normal modes of oscillation in the Sun to underlying flows. The theory is based on first-Born perturbation theory, and the analysis is carried out…
Observations show that the solar p-mode frequencies change with the solar cycle. The horizontal-phase-velocity dependence of the relative frequency change, scaled by mode mass, provides depth information on the perturbation in the solar…
We investigate the behavior of the intermediate-degree mode frequencies of the sun during the current extended minimum phase to explore the time-varying conditions in the solar interior. Using contemporaneous helioseismic data from GONG and…
Solar p-mode frequencies vary with solar activity. It is important to take this into account when comparing the frequencies observed from epochs that span different regions of the solar cycle. We present details of how to correct observed…
The Helioseismic and Magnetic Imager (HMI) has just started producing data that will help determine what the sources and mechanisms of variability in the Sun's interior are. The instrument measures the Doppler shift and the polarization of…
Rossby waves play an important role in mediating the angular momentum of rotating spherical fluids, creating weather on Earth and tuning exoplanet orbits in distant stellar systems (Ogilvie 2014). Their recent discovery in the solar…
Although it is well known that the solar acoustic mode frequency increases as the solar activity increases, the mechanism behind it is still unknown. Mode frequencies with 20 < l < 900 obtained by applying spherical harmonic decomposition…
We seek to address whether solar-cycle frequency shifts of the Sun's low-l p modes `distort' the underlying shapes of the mode peaks, when those peaks are observed in power frequency spectra made from data spanning large fractions, or more,…
We study the effect of localized sound-speed perturbations on global mode frequencies by applying techniques of global helioseismology on numerical simulations of the solar acoustic wave field. Extending the method of realization noise…
We perform a two-dimensional inversion of f-mode travel times to determine near-surface solar flows. The inversion is based on optimally localized averaging of travel times. We use finite-wavelength travel-time sensitivity functions and a…
Retrograde Rossby waves, measured to have significant amplitudes in the Sun, likely have notable implications for various solar phenomena. Rossby waves create small-amplitude, very-low frequency motions (on the order of the rotation rate…
... [C]urrent stellar models predict oscillation frequencies that are systematically affected by simplified modelling of the near-surface layers. We use three-dimensional radiation hydrodynamics simulations to better model the near-surface…
We describe an approach for finding the eigenfrequencies of solar acoustic modes (p modes) in a convective envelope in the WKB limit. This approximation restricts us to examining the effects of fluid motions which are large compared to the…
Using time-distance local helioseismology flow maps within 1 Mm of the solar photosphere, we detect inflows toward activity belts that contribute to solar cycle scale variations in near-surface meridional flow. These inflows stretch out as…
Ring diagram analysis can be used to study large scale velocity fields in the outer part of the solar convection zone. All previous works assume that the peak profiles in the solar oscillation power spectrum are symmetric. However, it has…
The principal aim of observational helioseismology is to determine mode parameters of the solar oscillations as accurately as possible. Yet estimates of the mode parameters are subject to many sources of noise, including inevitable gaps in…
The frequencies of solar oscillations are known to change with solar activity. We use Principal Component Analysis to examine these changes with high precision. In addition to the well-documented changes in solar normal mode oscillations…
The oscillation frequencies observed in Sun-like stars are susceptible to being shifted by magnetic activity effects. The measured shifts depend on a complex relationship involving the mode type, the field strength and spatial distribution…