1. First results from VIRGO on SoHO
- Author
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B. N. Andersen, Christoph Wehrli, Janine Provost, Douglas Gough, V. Domingo, T. Appourchaux, Takashi Sekii, Wolfgang Finsterle, J. Romero, Hansjörg Roth, T. Leifsen, T. Toutain, María Gómez, Gabrielle Berthomieu, Udo Telljohann, J. M. Pap, D. Crommelynck, M. Lombaerts, A. Jiménez, Claus Fröhlich, T. Roca Cortes, and Alain Fichot
- Subjects
Background noise ,Physics ,Sunspot ,Amplitude ,Observatory ,Physics::Space Physics ,Modulation (music) ,Astrophysics::Solar and Stellar Astrophysics ,Flux ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics ,Solar irradiance ,Excitation - Abstract
First results from the 4-6 months observations of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The time series are evaluated in terms of solar irradiance variability, solar background noise characteristics and p-mode oscillations. The solar irradiance is modulated by the passage of active regions across the disk, but not all of the modulation is straightforwardly explained in terms of sunspot flux blocking and facular enhancement. The observed p-mode frequencies are more-or-less in agreement with earlier measurements, but it is interesting to note that systematic differences seem to exist between the observations in different colours. There is also evidence that magnetic activity plays a significant role in the dynamics of the oscillations beyond its modulation of the resonant frequencies. Moreover, by comparing the amplitudes of different components of p-mode multiplets, each of which are influenced differently by spatial inhomogeneity, we have found that activity enhances excitation.
- Published
- 1997