ON THE STRANGE BEHAVIOUR OF THE P-MODE PEAK ASYMMETRY OBSERVED INGOLF DATA

摘要

We present new results on acoustic mode parame-rnter variations of low-degree acoustic modes obtainedrnfrom the observation made by the Global Oscillationsrnat Low Frequency (GOLF)and Michelson DopplerrnImager (MDI)instruments on board the ESA/NASArnSOHO satellite.An excellent level of agreementrnis found between the time variation of the di ?er-rnent mode parameters extracted from both datasets.rnHowever,while a signi ?cant variation of the meanrnpeak asymmetry in GOLF data is con ?rmed overrnthe epoch considered,a similar behavior can be onlyrnreckoned on the MDI asymmetries in the case ofrne=1,3 modes.In order to try to understand the likelyrnrelative contribution from genuine solar-cycle varia-rntions and the switch in the GOLF operating con ?g-rnuration as proposed by Thiery et al.(2001),we havernperformed an independent analysis of the both op-rneration modes of the GOLF observations,as well asrnan analysis of the phase difference between the twornvelocity measurements.