Search Publications
Automatic Tracking of Active Regions and Detection of Solar Flares in Solar EUV Images
Caballero, C.; Aranda, M. C.
Solar catalogs are frequently handmade by experts using a manual approach or semi-automated approach. The appearance of new tools is very useful because the work is automated. Nowadays it is impossible to produce solar catalogs using these methods, because of the emergence of new spacecraft that provide a huge amount of information. In this articl…
The Quest to Understand Supergranulation and Large-Scale Convection in the Sun
Hanasoge, Shravan M.; Sreenivasan, Katepalli R.
Surface granulation of the Sun is primarily a consequence of thermal transport in the outer 1 % of the radius. Its typical scale of about 1 - 2 Mm is set by the balance between convection, free-streaming radiation, and the strong density stratification in the surface layers. The physics of granulation is well understood, as demonstrated by the clo…
Hemispheric Distribution of Subsurface Kinetic Helicity and Its Variation with Magnetic Activity
Komm, R.; Pevtsov, A. A.; Gosain, S.
We study the hemispheric distribution of the kinetic helicity of subsurface flows in the near-surface layers of the solar convection zone and its variation with magnetic activity. We determine subsurface flows with a ring-diagram analysis applied to Global Oscillation Network Group (GONG) Dopplergrams and Dynamics Program data from the Michelson D…
Coronal Mass Ejections Observed at the Total Solar Eclipse on 13 November 2012
Hanaoka, Yoichiro; Nakazawa, Jun; Ohgoe, Osamu +2 more
White-light observations of the total solar eclipse on 13 November 2012 were made at two sites, where the totality occurred 35 min apart. The structure of the corona from the solar limb to a couple of solar radii was observed with a wide dynamic range and a high signal-to-noise ratio. An ongoing coronal mass ejection (CME) and a pre-CME loop struc…
A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. III. Catastrophe of the Eruptive Filament at a Magnetic Null Point and Formation of an Opposite-Handedness CME
Grechnev, V. V.; Chertok, I. M.; Uralov, A. M. +4 more
Our analysis in Papers I and II (Grechnev et al., Solar Phys.289, 289, 2014b and Solar Phys.289, 1279, 2014c) of the 18 November 2003 solar event responsible for the 20 November geomagnetic superstorm has revealed a complex chain of eruptions. In particular, the eruptive filament encountered a topological discontinuity located near the solar disk …
Analysis of Supergranule Sizes and Velocities Using Solar Dynamics Observatory (SDO)/ Helioseismic Magnetic Imager (HMI) and Solar and Heliospheric Observatory (SOHO)/ Michelson Doppler Imager (MDI) Dopplergrams
Williams, Peter E.; Pesnell, W. Dean; Beck, John G. +1 more
Co-temporal Doppler images from Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) have been analyzed to extract quantitative information about global properties of the spatial and temporal characteristics of solar supergranulation. Preliminary comparison…
Modified Homogeneous Data Set of Coronal Intensities
Minarovjech, M.; Rybanský, M.; Dorotovič, I. +1 more
The Astronomical Institute of the Slovak Academy of Sciences has published the intensities, recalibrated with respect to a common intensity scale, of the 530.3 nm (Fe XIV) green coronal line observed at ground-based stations up to the year 2008. The name of this publication is Homogeneous Data Set (HDS). We have developed a method that allows one …
Fractal and Multifractal Properties of Active Regions as Flare Precursors: A Case Study Based on SOHO/MDI and SDO/HMI Observations
Romano, P.; Zuccarello, F.; Ermolli, I. +3 more
Several studies indicate that fractal and multifractal parameters inferred from solar photospheric magnetic field measurements may help assessing the eruptive potential of Active Regions (ARs) and also predicting their flare activity. We further investigate this topic, by exploring the sensitivity of some parameters already used in the literature …
Solar Wind Electron Strahls Associated with a High-Latitude CME: Ulysses Observations
Lazar, M.; Poedts, S.; Pomoell, J. +2 more
Counterstreaming beams of electrons are ubiquitous in coronal mass ejections (CMEs) - although their existence is not unanimously accepted as a necessary and/or sufficient signature of these events. We continue the investigation of a high-latitude CME registered by the Ulysses spacecraft on 18 - 19 January 2002 (Dumitrache, Popescu, and Oncica, So…
Automated Detection of Low-Contrast Solar Features Using the Phase-Congruency Algorithm
Yang, Yunfei; Ji, Kaifan; Feng, Song +3 more
We propose a new feature-detection technique based on phase-congruency (PC) measurements to automatically recognize or enhance faint features in solar observations, such as off-limb coronal loops and umbral dots. Compared with other feature-detection methods that are based on gradient illuminance and imaging filtering, PC-based measurements are pa…