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Measurements of Frequencies of Solar Oscillations from the MDI Medium-l Program
Kosovichev, A. G.; Scherrer, P. H.; Schou, J. +2 more
Inversions of solar internal structure employ both the frequencies and the associated uncertainties of the solar oscillation modes as input parameters. In this paper we investigate how systematic errors in these input parameters may affect the resulting inferences of the sun's internal structure. Such systematic errors are likely to arise from ina…
High-Resolution Observations of the Extreme Ultraviolet Sun
Harrison, R. A.; Culhane, J. L.; Fludra, A. +9 more
This paper presents first results of the Coronal Diagnostic Spectrometer (CDS) recently launched aboard the Solar and Heliospheric Observatory (SOHO). CDS is a twin spectrometer, operating in the extreme ultraviolet range 151-785 Å. Thus, it can detect emission lines from trace elements in the corona and transition region which will be used to pro…
Application of Spectroscopic Diagnostics to Early Observations with the SOHO Coronal Diagnostic Spectrometer
Young, P. R.; Mason, H. E.; Harrison, R. A. +4 more
The Coronal Diagnostic Spectrometer (CDS) has as a scientific goal the determination of the physical parameters of the solar plasma using spectroscopic diagnostic techniques. Absolute intensities and intensity ratios of the EUV spectral emission lines can be used to obtain information on the electron density and temperature structure, element abun…
First Results on it P Modes from GOLF Experiment
Baudin, F.; García, R. A.; Pérez Hernández, F. +17 more
The GOLF experiment on the SOHO mission aims to study the internal structure of the Sun by measuring the spectrum of global oscillations in the frequency range 10-7 to 10-2 Hz. Here we present the results of the analysis of the first 8 months of data. Special emphasis is put into the frequency determination of the p modes, as…
First View of the Solar Core from GOLF Acoustic Modes
Baudin, F.; Christensen-Dalsgaard, J.; Eff-Darwich, A. +16 more
After 8 months of nearly continuous measurements the GOLF instrument, aboard SOHO, has detected acoustic mode frequencies of more than 100 modes, extending from 1.4 mHz to 4.9 mHz. In this paper, we compare these results with the best available predictions coming from solar models. To verify the quality of the data, we examine the asymptotic seism…
First Results from SWAN Lyman α solar wind mapper on SOHO
Schmidt, W.; Bertaux, J. L.; Lallement, R. +7 more
After one year of almost flawless operation on board the SOHO spacecraft poised at L1 Lagrange point, we report the main features of SWAN observations. SWAN is mainly dedicated to the monitoring of the latitude distribution of the solar wind by the Lα method. Maps of sky Lα emissions were recorded througout the year. The region of maximum emission…
Active Regions Observed in Extreme Ultraviolet Light by the Coronal Diagnostic Spectrometer on SOHO
Young, P. R.; Mason, H. E.; Harrison, R. A. +4 more
We present observations of five active regions made by the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO). CDS observes the Sun in the extreme ultraviolet range 150-780 Å. Examples of active region loops seen in spectral lines emitted at various temperatures are shown. Several classes of loops are identified…
Solar Wind and Chromospheric Network
Tu, C. -Y.; Marsch, E.
A physical model of the transition region, including upflow of the plasma in magnetic field funnels that are open to the overlying corona, is presented. A numerical study of the effects of Alfvén waves on the heating and acceleration of the nascent solar wind originating in the chromospheric network is carried out within the framework of a two-flu…
Observations of Polar Plumes with the SUMER Instrument on SOHO
Wilhelm, K.; Schühle, U.; Lemaire, P. +1 more
We present new observations of O vi 1032 Å line profiles in polar plumes, and inter-plume regions, on the disk and above the limb in the north coronal hole obtained with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument on the SOHO (Solar and Heliospheric Observatory) spacecraft. On 22 May 1996, a 5 x 5 arc min spectroheli…
Bursts of Explosive Events in the Solar Network
Wilhelm, K.; Innes, D. E.; Brekke, P. +1 more
Observations of the quiet-Sun network in the UV emission line Siiv 1393 Å over a time period of two hours are presented. Bursts of explosive events, highly Doppler-shifted emission, seem to be sporadically emitted from the brighter regions of the network lanes. Individual events have typical lifetimes of ≈ 1-6 min and come in bursts of up to 30 mi…