Solar -modes from 1979 days of the GOLF experiment

¹ Laboratoire d'Astrophysique, UMR 6525 du CNRS, Université de Nice-Sophia Antipolis, 06108 Nice Cedex 2, France
² C.N.R., 52 Charii Omar Ibn El Khattab, BP 8027, Rabat, Morocco
³ Département Cassini, UMR 6529 du CNRS, Observatoire de la Côte d'Azur, 06304 Nice, France
⁴ Laboratoire de Physique des Hautes Énergies et Astrophysique, Université Cadi Ayyad, Marrakech, Morocco

Corresponding author: B. Gelly, gelly@unice.fr

Received: 26 March 2002
Accepted: 10 July 2002

Abstract

With the GOLF instrument onboard the SoHO observatory, 1979 days of full-disc Doppler velocity observations have been compiled into a study of p-mode properties. We develop a multi-step iterative method (MSIM) algorithm to access all p-mode parameters while minimizing any perturbating effect or cross-talk between parameters during their determination. We present frequency and splitting tables, amplitudes, linewidths, line asymmetries, pseudo-modes, and background noise determinations. We have a first look at the changes induced by the transition from the low-activity to the high-activity part of solar cycle 23: we have recorded frequency shifts with a downturn at 3.7 mHz followed by a possible higher upturn, and linewidth changes to a good accuracy. We detect an effect on the noise background at 3 mHz possibly related to an interaction between noise and the modes and connected to the asymmetry of the profiles.