Related papers: Solar limb faculae: intensity contrast from two va…
High resolution and seeing-free spectroscopic observation of a decaying sunspot was done with the Solar Optical Telescope aboard Hinode satellite. The target was NOAA 10944 located in the west side of the solar surface from March 2 to March…
The Spectral Imaging of the Coronal Environment (SPICE) instrument is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths. In this paper, we present the concept, design, and pre-launch performance of…
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…
The contrasts of features in the quiet Sun are studied using filtergrams recorded by the Broad-band Filter Imager on the Hinode/Solar Optical Telescope. In a first step, the scattered light originating in the instrument is modeled using…
The diameter of the Sun has been measured using Baily's beads during central eclipses, observed with portable telescopes. A blend of tiny emission lines produced in the first several hundred kilometers above the photosphere gives a light…
Polar fields at the minimum of a sunspot cycle -- which are a manifestation of the radial component of the Sun's poloidal field -- are deemed to be the best indicator of the strength of the toroidal component, and hence the amplitude of the…
Various solar features can be seen on maps of the Sun in the mm and sub-mm wavelength range. The recently installed Atacama Large Millimeter/submillimeter Array (ALMA) is capable of observing the Sun in that wavelength range with an…
Plasma composition in the solar atmosphere differs between the photosphere and corona, producing an observable difference in elemental abundance known as the FIP effect. The FIP effect is characterised by the ratio of low to high FIP…
Polar brightening of the Sun at radio frequencies has been studied for almost fifty years and yet a disagreement persists between solar atmospheric models and observations. Some observations reported brightening values much smaller than the…
We analyzed the size, intensity, and magnetic field strength of sunspot umbrae to compare the present cycle 24 with the previous one. We used data of the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory and selected…
A giant, quiet-Sun filament was observed with the high-resolution Echelle spectrograph at the Vacuum Tower Telescope at Observatorio del Teide on 2011 November 15. A mosaic of spectra (10 maps of 100" X 182") was recorded simultaneously in…
Solar radius measurements and their variations -- if any -- are a difficult problem that has vexed researchers for decades. In this paper, we have attempted to clarify the various ways of expressing the definition ''solar diameter'', from a…
The Sun's axisymmetric flows, differential rotation and meridional flow, govern the dynamics of the solar magnetic cycle and variety of methods are used to measure these flows, each with its own strengths and weaknesses. Flow measurements…
The Sun's magnetic field is strongly structured over a broad range of scales. The magnetic spatial power spectral analysis provides a powerful tool to understand the various scales of magnetic fields and their interaction with plasma…
Waves have long been thought to contribute to the heating of the solar corona and the generation of the solar wind. Recent observations have demonstrated evidence of quasi-periodic longitudinal disturbances and ubiquitous transverse wave…
Context. Accurate photometry with ground based solar telescopes requires characterization of straylight. Scattering in Earth's atmosphere and in the telescope optics are potentially significant sources of straylight, for which the point…
The meridional circulation at high latitudes is crucial to the build-up and reversal of the Sun's polar magnetic fields. Here we characterize the axisymmetric flows by applying a magnetic feature cross-correlation procedure to high…
Observations of the Sun in the visible spectral range belong to standard measurements obtained by instruments both on the ground and in the space. Nowadays, both nearly continuous full-disc observations with medium resolution and dedicated…
The alpha effect is believed to play a key role in the generation of the solar magnetic field. A fundamental test for its significance in the solar dynamo is to look for magnetic helicity of opposite signs in the two hemispheres, and at…
The photospheric magnetic field outside of active regions and the network has a ubiquitous and dynamic line-of-sight component that strengthens from disk center to limb as expected for a nearly horizontal orientation. This component shows a…