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Variations in the solar wind density introduce variable delays into pulsar timing observations. Current pulsar timing analysis programs only implement simple models of the solar wind, which not only limit the timing accuracy, but can also…

Astrophysics · Physics 2009-11-13 X. P. You , G. B. Hobbs , W. A. Coles , R. N. Manchester , J. L. Han

The continuous wavelet transform is adapted to account for signal truncation through renormalization and by modifying the shape of the analyzing window. Comparison is made of the instant and integrated wavelet power with previous…

Data Analysis, Statistics and Probability · Physics 2010-11-23 Robert W. Johnson

The present paper reviews results derived from statistical studies on solar activity indices. The prolonged minimum phase of cycle 23 raised the question of peculiarities inherent in cycle 23. The most important solar activity index is the…

Solar and Stellar Astrophysics · Physics 2010-02-03 M. Temmer

The use of different solar activity indices like sunspot numbers, sunspot areas, flare index, magnetic fields, etc., allows us to investigate the time evolution of some specific features of the solar activity and the underlying dynamo…

Solar and Stellar Astrophysics · Physics 2013-10-11 Stefano Sello

At intermediate and high degree $l$, solar p- and f modes can be considered as surface waves. Using variational principle, we derive an integral expression for the group velocities of the surface waves in terms of adiabatic eigenfunctions…

Solar and Stellar Astrophysics · Physics 2015-06-18 S. V. Vorontsov , V. A. Baturin , S. V. Ayukov , V. K. Gryaznov

Current-voltage measurements are a standard testing protocol to determine the efficiency of any solar cell. However, perovskite solar cells display significant kinetic phenomena that modify the performance at several time scales, due to…

Applied Physics · Physics 2024-07-03 Enrique H. Balaguera , Juan Bisquert

This paper presents a new numerical approach to the study of non-periodicity in signals, which can complement the maximal Lyapunov exponent method for determining chaos transitions of a given dynamical system. The proposed technique is…

Chaotic Dynamics · Physics 2016-08-14 R. Benítez , V. J. Bolós , M. E. Ramírez

Despite the remarkable progress in emerging solar cell technologies such as hybrid organic-inorganic perovskites, there are still significant limitations related to the stability of the devices and their non-ideal electrical behavior under…

Rotation is a significant characteristic of the Sun and other stars, and it plays an important role in understanding their dynamo actions and magnetic activities. In this study, the rotation of the solar chromospheric activity is…

Solar and Stellar Astrophysics · Physics 2020-10-22 Jing-Chen Xu , Peng-Xin Gao , Xiang-Jun Shi

The duration of activity growths in solar cycles is on average shorter than the duration of its declines. This asymmetry can result from fluctuations in dynamo parameters. A solar dynamo model with fluctuations in the $\alpha$-effect shows…

Solar and Stellar Astrophysics · Physics 2018-11-07 Leonid Kitchatinov , Alexander Nepomnyashchikh

The application of the Wavelet analysis and Fourier analysis to the dataset of variations of radiation fluxes of solar-like stars and the Sun is examined. In case of the Sun the wavelet-analysis helped us to see a set of values of periods…

Solar and Stellar Astrophysics · Physics 2012-04-06 E. A. Bruevich , I. K. Rozgacheva

Long-term observational data have information on the magnetic cycles of active stars and that of the Sun. The changes in the activity of our central star have basic effects on Earth, like variations in the global climate. Therefore…

Solar and Stellar Astrophysics · Physics 2015-05-13 Z. Kolláth , K. Oláh

It is shown that, the wavelet regression detrended fluctuations of the monthly sunspot number for 1749-2009 years exhibit strong periodicity with a period approximately equal to 3.7 years. The wavelet regression method detrends the data…

Solar and Stellar Astrophysics · Physics 2011-01-14 A. Bershadskii

Despite the known general properties of the solar cycles, a reliable forecast of the 11-year sunspot number variations is still a problem. The difficulties are caused by the apparent chaotic behavior of the sunspot numbers from cycle to…

Astrophysics · Physics 2009-11-13 I. N. Kitiashvili , A. G. Kosovichev

Coronal bright points (BPs) are numerous, bright, small-scale dynamical features found in the solar corona. Bright points have been observed to exhibit intensity oscillations across a wide range of periodicities and are likely an important…

Solar and Stellar Astrophysics · Physics 2023-11-01 Brad Ramsey , Erwin Verwichte , Huw Morgan

In this paper we use statistical complexity and information theory metrics to study structure within solar wind time series. We explore this using entropy-complexity and information planes, where the measure for entropy is formed using…

Solar and Stellar Astrophysics · Physics 2025-10-08 Venla Koikkalainen , Emilia Kilpua , Simon Good , Adnane Osmane

The hot and diffuse nature of the Sun's extended atmosphere allows it to persist in non-equilibrium states for long enough that wave-particle instabilities can arise and modify the evolution of the expanding solar wind. Determining which…

Treatments of the radio scattering due to density turbulence in the solar wind typically employ asymptotic approximations to the phase structure function. We use a general structure function (GSF) that straddles the asymptotic limits and…

Solar and Stellar Astrophysics · Physics 2015-09-28 Madhusudan Ingale

Wavelet analysis is proposed as a new tool for studying the large-scale structure formation of the universe. To reveal its usefulness, the wavelet decomposition of one-dimensional cosmological density fluctuations is performed. In contrast…

Astrophysics · Physics 2009-10-28 Yoshi Fujiwara , Jiro Soda

The temporal analysis of stellar activity evolution is usually dominated by a complex trade-off between model complexity and interpretability, often by neglecting the non-stationary nature of the process. Recent studies appear to indicate…

Solar and Stellar Astrophysics · Physics 2023-10-27 E. N. Velloso , F. Anthony , J. D. do Nascimento , L. F. Q. Silveira , J. Hall , S. H. Saar