88 citations · 301 across the 12 of their papers we have counts for
13 papers
Analyses on Christoph Clavius' Reports of Total Solar Eclipses in 1560 and 1567: Key References for the Centennial Variations of the Earth's Rotation Speed and the Solar Radius
Hisashi Hayakawa, Mitsuru Sôma, Jean-Pierre Rozelot +4
Variations in solar radius (hereafter R_Sun) is a key reference for solar magnetic activity in time. The sunlight amount may have varied with R_Sun and had an effect on the Earth's…
Sharper Than Ever: Do Modern Observations Pin Down the Solar Radius to Converge on New Standards?
Jean-Pierre Rozelot, Alexander Kosovichev
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…
Analyses on Wassenius' Report for Total Solar Eclipse in 1733: Quantifications of the Solar Radius and the Earliest Reported Prominences
Hisashi Hayakawa, Mitsuru Sôma, Noortje Peek +3
Total solar eclipses (TSEs) offer a unique opportunity to observe the solar atmosphere, detect limb phenomena, and accurately measure the solar radius. Following the TSE in 1733, W…
Structure and Dynamics of the Sun's Interior Revealed by Helioseismic and Magnetic Imager
Alexander Kosovichev, Sarbani Basu, Yuto Bekki +43
High-resolution helioseismology observations with the Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) provide a unique three-dimensional view of the…
Improving Our Knowledge of the Solar Near-Surface Shear Layer: The Special Case of the Leptocline
Jean-Pierre Rozelot, Alexander Kosovichev, Irina Kitiashvili
The discovery of the solar activity cycle was linked from the outset to the observation of the temporal variability of sunspots, which we know to be the result of complex processes…
Solar polar brightening and radius at 100 and 230 GHz observed by ALMA
Caius L. Selhorst, Paulo J. A. Simões, Roman Brajša +8
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 ob…
Temporal and Periodic Variations of Sunspot Counts in Flaring and Non-flaring Active Regions
A. Kilcik, V. Yurchyshyn, B. Donmez +3
We analyzed temporal and periodic behavior of sunspot counts (SSCs) in flaring (C, M, or X class flares), and non-flaring active regions (ARs) for the almost two solar cycles (1996…
A brief history of the solar diameter measurements: a critical quality assessment of the existing data
Jean Pierre Rozelot, Alexander G. Kosovichev, Ali Kilcik
The size of the diameter of the Sun has been debated for a very long time. First tackled by the Greek astronomers from a geometric point of view, an estimate, although incorrect, h…
Active Latitude Oscillations Observed on the Sun
A. Kilcik, V. Yurchyshyn, F. Clette +2
We investigate periodicities in mean heliographic latitudes of sunspot groups, called active latitudes, for the last six complete solar cycles (1945-2008). For this purpose, the Mu…
Sunspot Count Periodicities in Different Zurich Sunspot Group Classes since 1986
A. Kilcik, A. Ozguc, V. B. Yurchyshyn +1
In this study, we used two methods to investigate the periodic behavior of sunspot counts in four categories for the time period January 1986-October 2013. These categories include…
Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles
A. Kilcik, V. B. Yurchyshyn, V. Abramenko +4
Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles…
Helioseismic test of non-homologous solar radius changes with the 11-year activity cycle
S. Lefebvre, A. G. Kosovichev, J. P. Rozelot
Recent models of variations of the Sun's structure with the 11-year activity cycle by Sofia et al (2005) predict strong non-homologous changes of the radius of subsurface layers, d…
Solar quadrupole moment and purely relativistic gravitation contributions to Mercury's perihelion Advance
S. Pireaux, J. P. Rozelot, S. Godier
The perihelion advance of the orbit of Mercury has long been one of the observational cornerstones for testing General Relativity (G.R.). The main goal of this paper is to discuss…