Search Publications
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…
The Mg/Ne abundance ratio in a recently emerged flux region observed by CDS
Young, P. R.; Mason, H. E.
Evidence for the existence of the FIP-effect in the transition region is presented here based on recent observations from the Coronal Diagnostic Spectrometer (CDS) on-board the Solar and Heliospheric Observatory (SOHO). Observations of an emerging flux region in lines of Mgv-vii and Nevi-vii reveal differences in the relative Mg/Ne abundance of a …
Flows and Dynamics in the Corona Observed with the Coronal Diagnostic Spectrometer (cds)
Harrison, R. A.; Kjeldseth-Moe, O.; Haugan, S. V. H. +5 more
EUV spectra obtained with the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) show significant flows of plasma in active region loops, both at coronal and transition region temperatures. Wavelength shifts in the coronal lines Mgix 368 Å and Mgx 624 Å corresponding to upflows in the plasma reaching velocities …
Tri-Phonic Helioseismology: Comparison of Solar P Modes Observed by the Helioseismology Instruments Aboard SOHO
Henney, C. J.; Hoeksema, J. T.; Baudin, F. +17 more
The three helioseismology instruments aboard SOHO observe solar p modes in velocity (GOLF and MDI) and in intensity (VIRGO and MDI). Time series of two months duration are compared and confirm that the instruments indeed observe the same Sun to a high degree of precision. Power spectra of 108 days are compared showing systematic differences betwee…