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We have observed selected Fraunhofer lines, both integrated over the Full Disk and for a small circular region near the center of the solar disk, on 1,215 days for the past 30 years. Full Disk results: Ca II K 393 nm nicely tracks the 11…

Astrophysics · Physics 2008-11-26 W. Livingston , L. Wallace , O. R. White , M. S. Giampapa

This paper explores a possible linkage between solar motion about the solar system center of mass and the quasi-periodicity evident in the pressure and temperature of planet atmospheres. We establish that dominant mid frequency range…

Earth and Planetary Astrophysics · Physics 2023-08-25 Ian R. Edmonds

Data obtained by the GONG and MDI instruments over the last seven years are used to study how solar dynamics -- both rotation and other large scale flows -- have changed with time. In addition to the well known phenomenon of bands of faster…

Astrophysics · Physics 2009-11-07 Sarbani Basu , H. M. Antia

The solar activity in the current, that is, the 24-th, sunspot cycle is analyzed. Cyclic variations in the sunspot number (SSN) and radiation fluxes in various spectral ranges have been estimated in comparison with the general level of the…

Solar and Stellar Astrophysics · Physics 2018-05-01 E. A. Bruevich , V. V. Bruevich , G. V. Yakunina

Wavelet spectral analysis is applied to the daily indices K (SK) registered in Huancayo geomagnetic observatory from 2000.0 to 2015.0, it has become possible to identify predominant periodic components with a confidence level of 95%. In…

Instrumentation and Methods for Astrophysics · Physics 2016-10-11 Domingo Rosales , Erick Vidal

We investigate the characteristics and the sources of the slow (< 450 km/s) solar wind during the four years (2006-2009) of low solar activity between Solar Cycles 23 and 24. We use a comprehensive set of in-situ observations in the…

Solar and Stellar Astrophysics · Physics 2016-10-05 E. K. J. Kilpua , M. S. Madjarska , N. Karna , T. Wiegelmann , C. Farrugia , W. Yu , K. Andreeova

The solar luminosity in the visible changes at the 10-3 level, following an 11 years period. In X-rays, which should not be there, the amplitude varies 100000 times stronger, making their mysterious origin since the discovery in 1938 even…

Solar and Stellar Astrophysics · Physics 2015-06-17 K. Zioutas , M. Tsagri , Y. K. Semertzidis , T. Papaevangelou , D. H. H. Hoffmann , V. Anastassopoulos

The data of sunspot numbers, sunspot areas and solar flare index during cycle 23 are analyzed to investigate the intermediate-term periodicities. Power spectral analysis has been performed separately for the data of the whole disk, northern…

Solar and Stellar Astrophysics · Physics 2009-11-16 Bhuwan Joshi , P. Pant , P. K. Manoharan

To better understand the influence of the activity cycle on the solar atmosphere, we report the time variation of the radius observed at 37 GHz ($\lambda$=8.1 mm) obtained by the Mets\"ahovi Radio Observatory (MRO) through Solar Cycles 22…

Solar and Stellar Astrophysics · Physics 2019-12-17 Caius L. Selhorst , Juha Kallunki , C. G. Giménez de Castro , Adriana Valio , Joaquim E. R. Costa

This Letter investigates the spectral characteristics of the interplanetary magnetic field fluctuations at proton scales during several time intervals chosen along the speed profile of a fast stream. The character of the fluctuations within…

Solar and Stellar Astrophysics · Physics 2015-09-30 R. Bruno , D. Telloni

In the present paper, we model the wind of solar analogues at different ages to investigate the evolution of the solar wind. Recently, it has been suggested that winds of solar type stars might undergo a change in properties at old ages,…

Solar and Stellar Astrophysics · Physics 2018-05-02 D. Ó Fionnagáin , A. A. Vidotto

We use Sun-as-a-star helioseismology data, collected by the Birmingham Solar-Oscillations Network (BiSON), to examine the relationship between the solar-cycle-induced frequency shifts of whole-Sun, low-angular degree solar p modes and…

Solar and Stellar Astrophysics · Physics 2026-05-29 William J. Chaplin , Sarbani Basu , Rachel Howe , Yvonne Elsworth , Steven J. Hale , Eleanor Murray

Severity of warming predicted by climate models depends on their Transient Climate Response (TCR). Inter-model spread of TCR has persisted at ~100% of its mean for decades. Existing observational constraints of TCR are based on observed…

Atmospheric and Oceanic Physics · Physics 2023-12-25 King-Fai Li , Ka-Kit Tung

Previous studies on the impact and influence of solar activity on terrestrial weather has yielded contradictory results in literature. Present study presents, on a global scale, the correlation between surface air temperature and two solar…

Earth and Planetary Astrophysics · Physics 2023-05-30 S. T. Ogunjo , A. B. Rabiu

The Sun provides the energy required to sustain life on Earth and drive our planet's atmospheric circulation. However, establishing a solid physical connection between solar and tropospheric variability has posed a considerable challenge…

Solar and Stellar Astrophysics · Physics 2020-02-06 Robert J Leamon , Scott W. McIntosh , Daniel R. Marsh

All p-mode parameters vary with time as a response to the changes induced by the cyclic behavior of solar magnetic activity. After the unusual long solar-activity minimum between cycles 23 and 24, where the p-mode parameters have shown a…

Solar and Stellar Astrophysics · Physics 2013-06-18 R. A. Garcia , D. Salabert , S. Mathur , C. Regulo , J. Ballot , G. R. Davies , A. Jimenez , R. Simoniello

The correlation scale and the Taylor scale are evaluated for interplanetary magnetic field fluctuations from two-point, single time correlation function using the Advanced Composition Explorer (ACE), Wind, and Cluster spacecraft data during…

Space Physics · Physics 2020-08-20 G. Zhou , H. -Q. He , W. Wan

We study a sample of 21 young and active solar-type stars with spectral types ranging from late F to mid K and characterize the behaviour of their activity. We apply the continuous period search (CPS) time series analysis method on 16 to 27…

Solar and Stellar Astrophysics · Physics 2016-03-21 Jyri Lehtinen , Lauri Jetsu , Thomas Hackman , Perttu Kajatkari , Gregory W. Henry

AIM: To study the variation of the angular momentum and the rotational kinetic energy of the Sun, and associated variations in the gravitational multipole moments, on a timescale of the solar cycle. METHOD: Inverting helioseismic rotational…

Astrophysics · Physics 2009-11-13 H. M. Antia , S. M. Chitre , D. O. Gough

Several recent studies utilizing different helioseismic methods have confirmed the presence of large-scale vorticity waves known as solar Rossby waves within the Sun. Rossby waves are distinct from acoustic waves, typically with longer…

Solar and Stellar Astrophysics · Physics 2023-08-15 M. Waidele , Junwei Zhao