FIRST RESULTS FROM VIRGO,THE EXPERIMENT FOR HELIOSEISMOLOGY AND SOLAR IRRADIANCE MONITORING ON SOHO   总被引：1，自引：0，他引：1  

Fröhlich  Claus  Andersen  Bo N.  Appourchaux  Thierry  Berthomieu  Gabrielle  Crommelynck  Dominique A.  Domingo  Vicente  Fichot  Alain  Finsterle  Wolfgang  Gómez  Maria F.  Gough  Douglas  Jiménez  Antonio  Leifsen  Torben  Lombaerts  Marc  Pap  Judit M.  Provost  Janine  Roca Cortés  Teodoro  Romero  José  Roth  Hansjörg  Sekii  Takashi  Telljohann  Udo  Toutain  Thierry  Wehrli  Christoph 《Solar physics》1997,170(1):1-25

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.  相似文献   

IN-FLIGHT PERFORMANCE OF THE VIRGO LUMINOSITY OSCILLATIONS IMAGER ABOARD SOHO     

Appourchaux  Thierry  Andersen  Bo N.  Fröhlich  Claus  Jiménez  Antonio  Telljohann  Udo  Wehrli  Christoph 《Solar physics》1997,170(1):27-41

The Luminosity Oscillations Imager (LOI) is a part of the VIRGO instrument aboard the Solar and Heliospheric Observatory (SOHO). The scientific objective of the LOI experiment is to identify and characterize pressure and internal gravity oscillations of the Sun by observing the radiance variations. The LOI is a low-resolution imager with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 nm. The low resolution capability of the instrument allows the identification of individual azimuthal orders for l = 0 to 7, without suffering the mixing that affects integrated solar disk instruments. The performance, calibrations and instrumental effects of the LOI are described together with the procedures for extracting the solar p modes.  相似文献   

VIRGO: Experiment for helioseismology and solar irradiance monitoring   总被引：1，自引：0，他引：1  

Claus Fröhlich  José Romero  Hansjörg Roth  Christoph Wehrli  Bo N. Andersen  Thierry Appourchaux  Vicente Domingo  Udo Telljohann  Gabrielle Berthomieu  Philippe Delache  Janine Provost  Thierry Toutain  Dominique A. Crommelynck  André Chevalier  Alain Fichot  Werner Däppen  Douglas Gough  Todd Hoeksema  Antonio Jiménez  Maria F. Gómez  José M. Herreros  Teodoro Roca Cortés  Andrew R. Jones  Judit M. Pap  Richard C. Willson 《Solar physics》1995,162(1-2):101-128

The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to the duration of the mission. With these data helioseismological methods can be used to probe the solar interior. Certain characteristics of convection and its interaction with magnetic fields, related to, for example, activity, will be studied from the results of the irradiance monitoring and from the comparison of amplitudes and phases of the oscillations as manifest in brightness from VIRGO, in velocity from GOLF, and in both velocity and continuum intensity from SOI/MDI. The VIRGO experiment contains two different active-cavity radiometers for monitoring the solar constant, two three-channel sunphotometers (SPM) for the measurement of the spectral irradiance at 402, 500 and 862 nm, and a low-resolution imager (LOI) with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 um. In this paper the scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described in detail, and their measured performance is given.died 13 October 1994  相似文献