• DOI:10.1007/978-94-011-5236-5_1
• Corpus ID: 55066732

FIRST RESULTS FROM VIRGO, THE EXPERIMENT FOR HELIOSEISMOLOGY AND SOLAR IRRADIANCE MONITORING ON SOHO

@article{Frhlich1997FIRSTRF,
  title={FIRST RESULTS FROM VIRGO, THE EXPERIMENT FOR HELIOSEISMOLOGY AND SOLAR IRRADIANCE MONITORING ON SOHO},
  author={Claus Fr{\"o}hlich and Bo Nyborg Andersen and Thierry Appourchaux and Gabrielle Berthomieu and Dominique A. H. Crommelynck and Vicente Domingo and Alain Fichot and Wolfgang Finsterle and Mar{\'i}a F. G{\'o}mez and Douglas Gough and A. C. Lopez Jimenez and Torben Leifsen and Marcel Lombaerts and Judit Pap and Janine Provost and T. Roca cort{\'e}s and Jos{\'e} Romero and Hansj{\"o}rg Roth and Takashi Sekii and Udo Telljohann and Thierry Toutain and Christoph Wehrli},
  journal={Solar Physics},
  year={1997},
  volume={170},
  pages={1-25}
}

• C. Fröhlich, B. Andersen, +19 authors C. Wehrli
• Published 1997
• Physics
• Solar Physics

First results from the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The observations started mid-January 1996 for the radiometers and sunphotometers and near the end of March for the luminosity oscillation imager. The performance of all the instruments is very good, and the time series of the first 4–6 months 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. Helioseismic inversions of the observed p-mode frequencies are more-or-less in agreement with the latest standard solar models. The comparison of VIRGO results with earlier ones shows 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 ofp -mode multiplets, each of which are influenced differently by spatial inhomogeneity, we have found that activity enhances excitation.