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This paper is intended to serve as the first version of the "SOHO User Manual", a "how to" guide for those interested in analyzing existing SOHO data, or proposing new SOHO observations. Questions addressed are, how to use the SOHO catalogs, where to find the appropriate data analysis software, how to request permission to use proprietary data, how to propose and prepare SOHO observing programs. In an outlook to the future I will emphasize the potential for joint observations during the rising phase of the cycle in the extended SOHO mission, collaborations with Yohkoh, Ulysses, and TRACE, as well as with the ISTP spacecraft. [ABSTRACT FROM AUTHOR]

Our knowledge of the the solar atmosphere comes from the light analysis. The ultraviolet wavelength is the privileged spectral range to study the solar plasma in several stages of ionization emitted from the chromosphere to the corona. Starting with basic notions of spectroscopy, an overview of important parameters is given. Then, after a short description of classical spectrometers, a detailed analysis of the properties of the mountings used on SOHO is performed; some examples are shown. I discuss how to separate the real solar signal from the instrumental contribution. From what has been learnt on the Sun during the last two decades, I make a prospective for future solar spectrometers developments. [ABSTRACT FROM AUTHOR]

A selection of topics in plasma physics and hydrodynamics relevant to the heliosphere is presented. The first three sections cover basic defining properties of a plasma, the essentials of particle orbit theory, including conservation of magnetic moment and the various drifts, and an introduction to kinetic theory, with an heuristic derivation of relaxation times. The fourth section is devoted to the hydrodynamic description of the solar wind, and is a pedagogical introduction to Parker's theory as well as to the methods of hydrodynamic and plasma stability. In the fifth and final section we return to the kinetic description of the solar wind plasmas and explore recent versions of the collisionless, or exospheric, models of wind acceleration, and compare their predictive merits and faults with those of the more widely studied fluid theories vis à vis in situ and remote observations of the corona and wind. [ABSTRACT FROM AUTHOR]

Radiation plays an important role, firstly in determining the structure of stars through the dominant role radiation plays in the energy balance (in some objects also in the momentum balance), secondly because we diagnose astrophysical plasma through the emitted electromagnetic radiation. These lectures discuss the diagnostic use of optically thick spectral lines and continua with special emphasis on the Sun. Modern methods to solve the equations of radiative transfer and statistical equilibrium are outlined. We stress the importance of solving self-consistently for the coupling between radiation and hydrodynamics for understanding the dynamic outer atmosphere of the Sun and review some results from such radiation hydrodynamics simulations. [ABSTRACT FROM AUTHOR]

Superb observations are now being obtained with the ESA/NASA Solar Heliospheric Observatory (SOHO). In these lectures, I discuss the spectroscopic diagnostic techniques used to analyse ultraviolet and X-ray spectra. Intensities of the spectral emission lines can be used to determine the electron density and temperature structure, element abundances and dynamic nature of different features in the solar transition region and corona. To ensure that these techniques are accurate it is necessary to model all the important atomic processes with the best available atomic data calculations. I discuss the analysis of SOHO spectra and look towards other astrophysical UV and X-ray observations. [ABSTRACT FROM AUTHOR]

A concise tutorial review is given of solar wind observations and theory with emphasis on the more recent findings from the Ulysses and SOHO missions, in particular about the plasma state and structure of the polar coronal holes, and on theoretical efforts to model the coronal hole flows and the fast solar wind emanating therefrom. The structure of the large-scale corona is discussed and the microstate of the solar wind in terms of particle and wave observations is analysed. Observational evidence is mounting that the magnetically open coronal holes are far away from a state of local thermodynamic equilibrium, as is the associated interplanetary solar wind, and that they differ substantially in their plasma parameters from the low-latitude streamers with closed magnetic fields, which only open intermittently to release the slow solar wind. The coronal sources and their plasma boundary conditions as well as the interplanetary constraints on the wind models are presented and discussed. Modern theories and models of the solar wind are reviewed. First the basic concept of the single-fluid Parker-type model is outlined, and then two-fluid models are described, in particular those incorporating strong heating of protons close to the Sun, which yields fast acceleration with the terminal wind speed being attained within 10 R⊙. Finally, the most recent modelling efforts to generate the wind plasma through ionization in the chromospheric network are presented. [ABSTRACT FROM AUTHOR]

Chromospheres and coronae owe their existence to mechanical heating. In the present work the mechanisms which are thought to provide steady mechanical heating are reviewed. These mechanisms can be classified as hydrodynamical- and magnetic heating mechanisms and each of these can be subdivided further on basis of the fluctuation frequency. Rapid fluctuations generated by the turbulence in the convection zones lead to acoustic waves and to mhd waves (AC-mechanisms), slow fluctuations to pulsational waves and to stressed fields with current sheets (DC-mechanisms). Solar and stellar observations, as well as acoustic and mhd wave generation rate computations on basis of convection zone models and a Kolmogorov-type energy spectrum representation for the turbulence, provide great progress towards the understanding of the complete dependence of the chromospheres and coronae on the properties of the underlying stars. [ABSTRACT FROM AUTHOR]

The magnetic field of the Sun is thought to be produced by a dynamo in the solar interior and exhibits its greatest influence on the solar plasma in the tenuous outer layers of the solar atmosphere, where it lies at the heart of almost every major phenomenon. Most direct observations of the magnetic field are restricted to the solar surface, however. Both observational and theoretical methods have been employed heavily to obtain information on and an understanding of solar magnetism. It is the aim of these lecture notes to impart some of this knowledge to the reader: knowledge both of the magnetic field and of some of the methods used to investigate it. First a short overview of the structure of magnetic fields in the observable layers of the Sun is given. This is followed by an introduction to the Zeeman effect and polarized light, which are fundamental to the measurement of the solar magnetic field, and to the magnetohydrostatic description of solar magnetic fields. Finally, current understanding of the small (magnetic elements) and large (sunspots) magnetic features observed in the solar photosphere is summarized. [ABSTRACT FROM AUTHOR]

In the last two decades, the study of global solar oscillations has provided the only effective method to probe the structure of stars, and particularly that of our Sun. As will be seen throughout this short course, we now know the Sun much better than before thanks to Helioseismology. However, the detection of such normal modes of vibration of the Sun has only been possible recently due to the combination of two factors: first the signals to measure, although almost periodic, have very small amplitudes as compared to noise, and second, instrumental and observing techniques have not reached the required sensitivity until now. Here we will look at the observational parameters that can be best measured, in terms of S/N, as well as the ultimate noise that is required in order to observe the solar oscillations. Further, we will review the current instruments and techniques that are able to do so with special emphasis on those onboard the SOHO satellite. However, getting the observations is not the end of the story; it is only after waiting for the acquisition of long time series and after applying sophisticated analysis techniques, that a comprehensive picture can be seen and observational parameters can be compared to theoretical predictions in what is known as the Forward Problem of Helioseismology. We will also see how the differences between the predictions and the actual Sun lead us to calculate the internal structure of the models through what is called the Inverse Problem in Helioseismology. [ABSTRACT FROM AUTHOR]