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Astron. Astrophys. 318, 970-974 (1997)

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An estimate of the solar background irradiance power spectrum

M.C.  Rabello Soares 1, T.  Roca  Cortés 1, A.  Jiménez 1, B.N.  Andersen 2 and T.  Appourchaux 3

1 Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife, Spain
2 Norwegian Space Centre P.O.Box 85, Smestad, N-0309 Oslo, Norway
3 Space Science Department of ESA, ESTEC, P.O.Box 299, 2200 AG Noordwijk, The Netherlands

Received 8 December 1995 / Accepted 17 June 1996


Knowledge of the solar irradiance background is of great importance to solar and stellar physics. In particular, its contribution to the solar oscillations power spectrum is highly relevant as it represents the ultimate limit to the sensitivity of solar oscillations' observations. An analysis of the power spectra of the solar photometric data coming from four different instruments - two space-borne (ACRIM and IPHIR) and two earth-based instruments (SLOT and LOI-T) - has been performed to obtain the upper limit to the solar irradiance background's spectrum. These observations have been compared to a numerical model computed for the non-coherent solar surface phenomena, namely granulation, mesogranulation and supergranulation. There is an overall good agreement between the general trend of the model and the observed data.

Key words: Sun: oscillations – Sun: general – Sun: granulation

Send offprint requests to: T. Roca Cortés (trc@iac.es)


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© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998