390 citations · 12k across the 248 of their papers we have counts for
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Convectively driven vortex flows in the Sun
J. A. Bonet, I. Marquez, J. Sanchez Almeida +2
We have discovered small whirlpools in the Sun, with a size similar to the terrestrial hurricanes (<~0.5 Mm). The theory of solar convection predicts them, but they had remained el…
Evidence of convective rolls in a sunspot penumbra
V. Zakharov, J. Hirzberger, T. L. Riethmueller +2
aims: We study the recently discovered twisting motion of bright penumbral filaments with the aim of constraining their geometry and the associated magnetic field. methods: A large…
Identification of different types of kink modes in coronal loops: principles and application to TRACE results
T. J. Wang, S. K. Solanki, M. Selwa
We explore the possible observational signatures of different types of kink modes (horizontal and vertical oscillations in their fundamental mode and second harmonic) that may aris…
A nanoflare model for active region radiance: application of artificial neural networks
M. Bazarghan, H. Safari, D. E. Innes +2
Context. Nanoflares are small impulsive bursts of energy that blend with and possibly make up much of the solar background emission. Determining their frequency and energy input is…
Are there field-free gaps near tau=1 in sunspot penumbrae?
J. M. Borrero, S. K. Solanki
The vertical stratification of the magnetic field strength in sunspot penumbrae is investigated by means of spectropolarimetric observations at high spatial resolution from the Hin…
Evidence for polar jets as precursors of polar plume formation
N. -E. Raouafi, G. J. D. Petrie, A. A. Norton +2
Observations from the Hinode/XRT telescope and STEREO/SECCHI/EUVI are utilized to study polar coronal jets and plumes. The study focuses on the temporal evolution of both structure…
Stratification of sunspot umbral dots from inversion of Stokes profiles recorded by Hinode
T. L. Riethmueller, S. K. Solanki, A. Lagg
This work aims to constrain the physical nature of umbral dots (UDs) using high-resolution spectropolarimetry. Full Stokes spectra recorded by the spectropolarimeter on Hinode of 5…
Toroidal versus poloidal magnetic fields in Sun-like stars: a rotation threshold
P. Petit, B. Dintrans, S. K. Solanki +8
From a set of stellar spectropolarimetric observations, we report the detection of surface magnetic fields in a sample of four solar-type stars, namely HD 73350, HD 76151, HD 14623…
Spectral irradiance variations: Comparison between observations and the SATIRE model on solar rotation time scales
Yvonne C. Unruh, Natalie A. Krivova, Sami K. Solanki +2
Aims: We test the reliability of the observed and calculated spectral irradiance variations between 200 and 1600 nm over a time span of three solar rotations in 2004. Methods: We c…
On the potential value of Ca II K spectroheliogram time-series for solar activity and irradiance studies
I. Ermolli, S. K. Solanki, A. G. Tlatov +3
Various observatories around the globe started regular full-disk imaging of the solar atmosphere in the Ca II K line since the early decades of the 20th century. The archives made…
Comparing magnetic field extrapolations with measurements of magnetic loops
T. Wiegelmann, A. Lagg, S. K. Solanki +2
We compare magnetic field extrapolations from a photospheric magnetogram with the observationally inferred structure of magnetic loops in a newly developed active region. This is t…
Hanle Effect Diagnostics of the Coronal Magnetic Field - A Test Using Realistic Magnetic Field Configurations
N. -E. Raouafi, S. K. Solanki, T. Wiegelmann
Our understanding of coronal phenomena, such as coronal plasma thermodynamics, faces a major handicap caused by missing coronal magnetic field measurements. Several lines in the UV…
Evidence of magnetic field wrapping around penumbral filaments
J. M. Borrero, B. W. Lites, S. K. Solanki
We employ high-spatial resolution spectropolarimetric observations from the Solar Optical Telescope on-board the Hinode spacecraft to investigate the fine structure of the penumbra…
The velocity structure of moving magnetic feature pairs around sunspots: support for the U-loop model
Jun Zhang, S. K. Solanki, J. Woch +1
Using data recorded by the Michelson Doppler Imager (MDI) instrument on the Solar and Heliospheric Observatory (SOHO), we have traced 123 pairs of opposite magnetic polarity moving…
Low-lying magnetic loops in the solar internetwork
M. J. Martinez Gonzalez, M. Collados, B. Ruiz Cobo +1
The aim of this work is to study the structure of the magnetic field vector in the internetwork and search for the presence of small-scale loops. We invert 1.56 micron spectropolar…
Discovery of inward moving magnetic enhancements in sunspot penumbrae
Jun Zhang, S. Solanki, J. Woch
Sunspot penumbrae show a fine structure in continuum intensity that displays considerable dynamics. The magnetic field, in contrast, although also highly structured, has appeared t…
Modified p-modes in penumbral filaments?
D. S. Bloomfield, S. K. Solanki, A. Lagg +2
Aims: The primary objective of this study is to search for and identify wave modes within a sunspot penumbra. Methods: Infrared spectropolarimetric time series data are inverted us…
Sensitivity of solar off-limb line profiles to electron density stratification and the velocity distribution anisotropy
N. -E. Raouafi, S. K. Solanki
The effect of the electron density stratification on the intensity profiles of the H I Ly- line and the O VI and Mg X doublets formed in solar coronal holes is investigated. We…
Properties of solar polar coronal plumes constrained by Ultraviolet Coronagraph Spectrometer data
N. -E. Raouafi, J. W. Harvey, S. K. Solanki
We investigate the plasma dynamics (outflow speed and turbulence) inside polar plumes. We compare line profiles (mainly of \ion{O}{6}) observed by the UVCS instrument on SOHO at th…
Observations of Running Waves in a Sunspot Chromosphere
D. Shaun Bloomfield, Andreas Lagg, Sami K. Solanki
Spectropolarimetric time series data of the primary spot of active region NOAA 9448 were obtained in the Si I 10827 Åline and the He I 10830 Åmultiplet with the Tenerife Infrared P…
Stokes diagnostics of simulated solar magneto-convection
S. Shelyag, M. Schuessler, S. K. Solanki +1
We present results of synthetic spectro-polarimetric diagnostics of radiative MHD simulations of solar surface convection with magnetic fields. Stokes profiles of Zeeman-sensitive…
Reconstruction of solar irradiance using the Group sunspot number
L. Balmaceda, N. A. Krivova, S. K. Solanki
We present a reconstruction of total solar irradiance since 1610 to the present based on variations of the surface distribution of the solar magnetic field. The latter is calculate…
A nanoflare model of quiet Sun EUV emission
Anuschka Pauluhn, Sami K. Solanki
Nanoflares have been proposed as the main source of heating of the solar corona. However, detecting them directly has so far proved elusive, and extrapolating to them from the prop…
Magnetic flux transport on active cool stars and starspot lifetimes
Emre Isik, Manfred Schuessler, Sami K. Solanki
We carry out numerical simulations of the surface evolution of bipolar magnetic regions (BMRs) and magnetic spots on stars, which have radii and surface rotational shears of AB Dor…