Solar internal sound speed as inferred from combinedBiSON and LOWL oscillation
نویسندگان
چکیده
Observations of the Sun with the LOWL instrument provide a homogeneous set of solar p-mode frequencies from low to intermediate degree which allows one to determine the structure of much of the solar interior avoiding systematic errors that are introduced when diierent data sets are combined, i.e., principally the eeects of solar cycle changes on the frequencies. Unfortunately, the LOWL data set contains very few of the lowest-degree modes, which are essential for determining reliably the structure of the solar core { in addition, these lowest-degree data have fairly large associated uncertainties. However, observations made by the Birmingham Solar-Oscillations Network (BiSON) in integrated sunlight provide high-accuracy measurements of a large number of low-degree modes. In this paper we demonstrate that the low-degree mode set of the LOWL data can be successfully combined with the more accurate BiSON data, provided the observations are contemporaneous for those frequencies where the solar-cycle-induced eeects are important. We show that this leads to a factor-of-two decrease in the error on the inferred sound speed in the solar core. We nd that the solar sound speed is higher than in solar models for r < 0:2R. The density of the solar core is, however, lower than that in solar models.
منابع مشابه
Solar internal sound speed as inferred from combinedBiSON and
Observations of the Sun with the LOWL instrument provide a homogeneous set of solar p-mode frequencies from low to intermediate degree which allows one to determine the structure of much of the solar interior avoiding systematic errors that are introduced when diierent data sets are combined, i.e., principally the eeects of solar cycle changes on the frequencies. Unfortunately, the LOWL data se...
متن کاملSolar internal sound speed as inferred from combined BiSON and LOWL oscillation frequencies
Observations of the Sun with the LOWL instrument provide a homogeneous set of solar p-mode frequencies from low to intermediate degree which allows one to determine the structure of much of the solar interior avoiding systematic errors that are introduced when different data sets are combined, i.e., principally the effects of solar cycle changes on the frequencies. Unfortunately, the LOWL data ...
متن کاملar X iv : a st ro - p h / 02 07 40 2 v 1 1 8 Ju l 2 00 2 An Upper Limit on the Temporal Variations of the Solar Interior Stratification
We have analyzed changes in the acoustic oscillation eigenfrequencies measured over the past 7 years by the GONG, MDI and LOWL instruments. The observations span the period from 1994 to 2001 that corresponds to half a solar cycle, from minimum to maximum solar activity. These data were inverted to look for a signature of the activity cycle on the solar stratification. A one-dimensional structur...
متن کاملSensitivity of the Sound Speed to the Physical
We compare several largely independent calculations of solar models performed by diierent groups. As a reference is used the sound-speed proole extracted from GOLF+LOWL or GOLF+MDI data by S. Basu and J. Christensen-Dalsgaard. First, we show some eeects of the recent physical improvements included in the standard model: opacity calculations and nuclear reaction rates and the role of the solar a...
متن کاملConstraining Solar Core Rotation with Genetic Forward Modelling
We present a technique which uses forward modelling in conjunction with a genetic algorithm to nd the internal rotation proole which best reproduces a set of input frequency splittings. The genetic algorithm provides an eecient and robust method for global optimization. We evaluate the ability of this technique to determine the rotation proole in the solar core by applying it to artiicial datas...
متن کامل