A new perspective on the solar tachocline from long and very long time-series.

Korzennik, Sylvain; Eff-Darwich, Antonio
Referencia bibliográfica

American Astronomical Society Meeting Abstracts

Fecha de publicación:
6
2025
Número de autores
2
Número de autores del IAC
1
Número de citas
0
Número de citas referidas
0
Descripción
With some 15, 15 and 30 years of MDI, HMI and GONG observations, respectively, we have reached a new milestone in acquiring almost three decades of nearly continuous helioseismic observations. Moreover, an alternative fitting methodology for global helioseismology to the respective projects' pipeline has produced tables of individual mode frequencies using time-series of various lengths. These include long and very long time-series, namely 6.3 year and 12.6 year long time-series for all 3 instruments as well as a 25.2 year long one for GONG observations. By using such long and very long time-series the resulting tables of fitted parameters have produced very precise individual mode frequencies and rotational frequency splittings. Therefore we ought to revisit our traditional rotation inversion techniques and methodology to derive the best estimate of the solar internal rotation and in particular the properties of the tachocline. To achieve this, we have reassessed some of our preconceived conceptions, like the density of the model grid used for inversions, all the while we also have developed a new inversion methodology that uses an iterative technique to complement the classical regularized least square method. We present our latest results from inverting rotational frequency splittings derived from these long and very long time-series, using an optimized resolution near the tachocline. We show how our inferences were validated using simulations, the derived properties of the tachocline and, of course, how our inferences correspond to the rotation rate convolved by the respective averaging kernels, and recognize that these are averaged over the extent of the fitted time-series.