Related papers: Temporal Variations of High-Degree Solar p-Modes u…

Meridional flow is thought to play a very important role in the dynamics of the solar convection zone; however, because of its relatively small amplitude, precisely measuring it poses a significant challenge. Here we present a complete…

Data from the Michelson Doppler Imager (MDI) and Helioseismic and Magnetic Imager (HMI) are analyzed from 1996 to 2023 to investigate tilt angles ($\gamma$) of bipolar magnetic regions and Joy's Law for Cycles 23, 24, and a portion of 25.…

The results of determinations of the azimuthal and meridional velocities by time-distance helioseismology from Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) from May 2010 to September 2020 at latitudes from…

The work is devoted to the study of periodic structures in the magnetic field of the photosphere. The polarity of the Sun's magnetic fields shows cyclicity with periods of 1-3 years, which is possibly due to quasi-biennial variations that…

We study properties of waves of frequencies above the photospheric acoustic cut-off of $\approx$5.3 mHz, around four active regions, through spatial maps of their power estimated using data from Helioseismic and Magnetic Imager (HMI) and…

Using Doppler velocity data from the SOI/MDI instrument onboard the SoHO spacecraft, we do time-distance helioseismic inversions for sound-speed perturbations beneath 16 sunspots observed in high-resolution mode. We clearly detect ring-like…

We suggest a solution to an important problem of observational helioseismology of the separation of lines of solar acoustic (p) modes of low angular degree in oscillation power spectra by constructing optimal masks for Doppler images of the…

Although there are now some tentative signs that the start of cycle 24 has begun there is still considerable interest in the somewhat unusual behaviour of the current solar minimum and the apparent delay in the true start of the next cycle.…

Solar differential rotation exhibits a prominent feature: its cyclic variations over the solar cycle, referred to as zonal flows or torsional oscillations, are observed throughout the convection zone. Given the challenge of measuring…

Previous studies have used magnetic energy and helicity spectra, the latter computed using the two-scale method, to search for signatures of mean-field dynamos. In this study, we compare cotemporal HMI and SOLIS magnetograms to illustrate…

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…

In a recent paper (Svanda et al., 2008, A&A 477, 285) we pointed out that, based on the tracking of Doppler features in the full-disc MDI Dopplergrams, the active regions display two dynamically different regimes. We speculated that this…

Large-scale plasma flows in the Sun's convection zone likely play a major role in solar dynamics on decadal timescales. In particular, quantifying meridional motions is a critical ingredient for understanding the solar cycle and the…

The temporal variations of the rotation rate in the solar interior are studied using frequency splittings from Global Oscillations Network Group (GONG) data obtained during the period 1995-99. We find alternating latitudinal bands of faster…

Context. Recently our ability to study stars using asteroseismic techniques has increased dramatically, largely through the use of space based photometric observations. Work has also been done using ground based spectroscopic observations…

Aims: We aim to study the spot evolution and differential rotation in the magnetically active cool K-type giant star sigma Gem from broadband photometry and continuous spectroscopic observations that span 150 nights. Methods: We use…

The strength and morphology of the Sun's magnetic field evolves significantly during the solar cycle, with the overall polarity of the Sun's magnetic field reversing during the maximum of solar activity. Long-term changes are also observed…

High quality observations of the low degree p-modes exist for almost two complete solar cycles using the solar spectrophotometer Mark-I, located and operating at the Observatorio del Teide (Tenerife, Spain). In this work, the observations…

The detection of multiple mode harmonic kink oscillations in coronal loops enables to obtain information on coronal density stratification and magnetic field expansion using seismology inversion techniques. The inference is based on the…

High-precision pulsar timing requires accurate corrections for dispersive delays of radio waves, parametrized by the dispersion measure (DM), particularly if these delays are variable in time. In a previous paper we studied the Solar-wind…