E-Print Archive

There are 4524 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
Statistical analysis of solar Hα flares View all abstracts by submitter

Manuela Temmer   Submitted: 2002-10-02 09:35

A statistical analysis of a large data set of Hα flares comprising almost 100 000 single events that occurred during the period January 1975 to December 1999 is presented. We analyzed the flares evolution steps, i.e. duration, rise times, decay times and event asymmetries. Moreover, these parameters characterizing the temporal behavior of flares, as well as the spatial distribution on the solar disk, i.e. N-S and E-W asymmetries, are analyzed in terms of their dependency on the solar cycle. The main results are: 1) The duration, rise and decay times increase with increasing importance class. The increase is more pronounced for the decay times than for the rise times. The same relation is valid with regard to the brightness classes but in a weaker manner. 2) The event asymmetry indices, which characterize the proportion of the decay to the rise time of an event, are predominantly positive (ca. 90%). For about 50% of the events the decay time is even more than 4 times as long as the rise time. 3) The event asymmetries increase with the importance class. 4) The flare duration and decay times vary in phase with the solar cycle; the rise times do not. 5) The event asymmetries do not reveal a distinct correlation with the solar cycle. However, they drop during times of solar minima, which can be explained by the shorter decay times found during minimum activity. 6) There exists a significant N-S asymmetry over longer periods, and the dominance of one hemisphere over the other can persist for more than one cycle. 7) For certain cycles there may be evidence that the N-S asymmetry evolves with the solar cycle, but in general this is not the case. 8) There exists a slight but significant E-W asymmetry with a prolonged eastern excess.

Authors: M. Temmer, A. Veronig, A. Hanslmeier, W. Otruba, and M. Messerotti

Publication Status: A&A 375, 2001, 10491061
Last Modified: 2002-10-02 09:35
Go to main E-Print page  The differential emission measure distribution in the multi-loop corona  Energy Budget and Imaging Spectroscopy of a Compact Flare  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

Go to main E-Print pageGo to main E-Print page.
Previous AbstractPrevious Abstract.
Next AbstractNext Abstract.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
View All Abstracts By SubmitterView all abstracts by submitter.
Delete AbstractDelete abstract.

Latest Entries
Coronal seismology by slow waves in non-adiabatic conditions
Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform Transition
Changes of Magnetic Energy and Helicity in Solar Active Regions from Major Flares
Spectroscopic and Imaging Observations of Spatially Extended Magnetic Reconnection in the Splitting of a Solar Filament Structure
The Universality of Power Law Slopes in the Solar Photosphere and Transition Region Observed with HMI and IRIS
Turbulence and Anomalous Resistivity inside Near-Earth Magnetic Clouds
On the specific energy and pressure in near-Earth magnetic clouds
Solar Energetic Particle Event Associated with the 2012 July 23 Extreme Solar Storm
Investigation of Energetic Particle Release Using Multi-point Imaging and In Situ Observations
Shock Properties and Associated Characteristics of Solar Energetic Particles in the 2017 September 10 GLE event
Dimensionality of Solar Magnetic Reconnection
Microwave Perspective on Magnetic Breakout Eruption
Effects of Coronal Density and Magnetic Field Distributions on a Global Solar EUV Wave
Multi-spacecraft Observations of the Coronal and Interplanetary Evolution of a Solar Eruption Associated with Two Active Regions
Sun-to-Earth Characteristics of the 2012 July 12 Coronal Mass Ejection and Associated Geo-effectiveness
The effect of nanoflare flows on EUV spectral lines
On some features of the solar proton event on 2021 October 28 GLE73
The role and contribution of magnetic fields, characterized via their magnetic flux, to the statistical structuring of the solar atmosphere
Do periods of decayless kink oscillations of solar coronal loops depend on noise?
Automatic detection technique for solar filament oscillations in GONG data

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey

© 2000-2020 Solar Physics Group - Montana State University