SOLAR LOW-DEGREE P-MODE PARAMETERS AFTER 8 YEARS OF VELOCITY MEASUREMENTSWITH SOHO

摘要

More than 8 years of line-of-sight-velocity measurementsrnhave been collected by the SoHO spacecraft with GOLFrnand MDI instruments. In the present work we study low-rndegree acoustic-mode parameters: frequency, amplitude,rnline-width and splitting extracted from ～3000 days. Forrnthe modes at low frequency (below 2 mHz) they are notrnaffected by the solar magnetic cycle and we can computernthe full periodogram obtaining the mode parameters. Atrnhigher frequencies, the solar magnetic cycle introducesrnan important bias in all the parameters and a differentrnapproach is used. Segmented time series are analyzedrntogether u0002tting the mode parameters with a function de-rnpending on the solar cycle. Thus estimations of the modernparameters are obtained using the full 8 years statisticsrnrelative to the minimum of the solar cycle.