Search Publications
Catalogue of the 1997 SOHO-EIT coronal transient waves and associated type II radio burst spectra
Thompson, B. J.; Mann, G.; Aurass, H. +1 more
We compare the coronal transient wave phenomenon discovered by SOHO extreme ultraviolet observations (``EIT waves'') with the associated radio signature of a coronal shock wave (type II burst). 90% of the type II bursts are associated with an EIT wave. On average, the speed derived from the radio burst is about three times larger than the EIT wave…
Atomic data from the IRON Project. XL. Electron impact excitation of the Fe XIV EUV transitions
Young, P. R.; Mason, H. E.; Storey, P. J.
We calculate collision strengths and thermally averaged collision strengths for electron excitation between the forty energetically lowest levels of Fe13+. The scattering calculation is more complete than any previous work on this ion and significant differences are found in the excitation rates for many of the extreme ultra-violet (EUV…
Location of the activity responsible for the appearance of coronal mass ejections and the sites of their ejection from the solar surface.
Shilova, N. S.
The white-light films of coronal mass ejections for April - May, 1998 (SOHO LASCO C2, C3), retrieved from Internet, are considered. The positions of active regions on visible and back sides of the Sun for each day are studied. It is shown that a region of large flare can be localized at a distance not less than the solar radius from the place wher…
Relative intensity calibration of CDS-GIS detectors on SOHO using a plasma diagnostic technique
Landini, M.; Del Zanna, G.; Landi, E. +3 more
The internal intensity calibration of the Coronal Diagnostic Spectrometer (CDS) - Grazing Incidence Spectrometer (GIS) is studied using the Arcetri diagnostic method. A large number of spectral lines observed by the four GIS detectors in solar active and quiet regions is analysed in order to determine the relative intensity calibration curve of th…
Parametric representation of helioseismic data. I. A method for estimation of mode correlation
Ferrari, A.; Gelly, B.; Schmider, F. -X. +1 more
This paper describes a parametric method aimed at the estimation of correlation in the excitation of solar p modes. Unlike previous work which investigated the correlation in the statistical properties of the mode's power, rather we study the excitation signal itself. In this approach, each mode is represented as a second-order autoregressive proc…
The art of fitting p-mode spectra. I. Maximum likelihood estimation
Appourchaux, T.; Gizon, L.; Rabello-Soares, M. -C.
In this article we present our state of the art of fitting helioseismic p-mode spectra. We give a step by step recipe for fitting the spectra: statistics of the spectra both for spatially unresolved and resolved data, the use of Maximum Likelihood estimates, the statistics of the p-mode parameters, the use of Monte-Carlo simulation and the signifi…
Spectral decomposition by genetic forward modelling
Judge, P. G.; Brown, J. C.; Charbonneau, P. +3 more
We discuss the analysis of real and simulated line spectra using a genetic forward modelling technique. We show that this Genetic Algorithm (GA) based technique experiences none of the user bias or systematic problems that arise when faced with poorly sampled or noisy data. An important feature of this technique is the ease with which rigid a prio…
Numerical simulation of observations with GOLF on board SOHO
Roca Cortes, T.; Garcia, R. A.; Regulo, C.
The main objective of the GOLF Experiment (Global Oscillations at Low Frequencies) on-board the SOHO (Solar and Heliospheric Observatory) space mission is the quantitative knowledge of the internal structure of the Sun by measuring the spectrum of its global oscillations in a wide frequency range (30 nHz to 6 mHz). There is special interest in det…
The Arcetri spectral code for thin plasmas
Landini, M.; Landi, E.
The Arcetri spectral code allows to evaluate the spectrum of the radiation emitted by hot and optically thin plasmas in the spectral range 1 - 2000 Angstroms. The database has been updated including atomic data and radiative and collisional rates to calculate level population and line emissivities for a number of ions of the minor elements; a crit…
The art of fitting p-mode spectra. II. Leakage and noise covariance matrices
Appourchaux, T.; Gizon, L.; Rabello-Soares, M. -C.
In Part I we have developed a theory for fitting p-mode Fourier spectra assuming that these spectra have a multi-normal distribution. We showed, using Monte-Carlo simulations, how one can obtain p-mode parameters using ``Maximum Likelihood Estimators". In this article, hereafter Part II, we show how to use the theory developed in Part I for fittin…