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The correlation between solar irradiance and the 11-year solar activity cycle is evident in the body of measurements made from space, which extend over the past four decades. Models relating variation in solar irradiance to photospheric…

Solar and Stellar Astrophysics · Physics 2015-07-07 K. L. Yeo , N. A. Krivova , S. K. Solanki

Mutual quasi-periodicities near the solar-rotation period appear in time series based on the Earth's magnetic field, the interplanetary magnetic field, and signed solar-magnetic fields. Dominant among these is one at 27.03 +/- 0.02 days…

Astrophysics · Physics 2009-11-13 J. K. Lawrence , A. C. Cadavid , A. Ruzmaikin

Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI), we characterize both short-term (solar rotation) and long-term (solar cycle) changes of the solar spectral irradiance (SSI) between 265-500 nm during the on-going…

Solar and Stellar Astrophysics · Physics 2016-10-26 S. V. Marchenko , M. T. DeLand , J. L. Lean

The 11-year activity cycle of the Sun is a consequence of a dynamo process occurring beneath its surface. We analyzed photometric data obtained by the CoRoT space mission, showing solar-like oscillations in the star HD49933, for signatures…

Solar and Stellar Astrophysics · Physics 2010-11-03 Rafael A. Garcia , Savita Mathur , David Salabert , Jerome Ballot , Clara Regulo , Travis S. Metcalfe , Annie Baglin

Helioseismic data for solar cycles 23 and 24 have shown unequivocally that solar dynamics changes with solar activity. Changes in solar structure have been more difficult to detect. Basu & Mandel (2004) had claimed that the then available…

Solar and Stellar Astrophysics · Physics 2020-11-11 Courtney B. Watson , Sarbani Basu

With the unique database from Michelson Doppler Imager aboard the Solar and Heliospheric Observatory in an interval embodying solar cycle 23, the cyclic behavior of solar small-scale magnetic elements is studied. More than 13 million…

Solar and Stellar Astrophysics · Physics 2015-05-27 C. L. Jin , J. X. Wang , Q. Song , H. Zhao

We study solar modulation of galactic cosmic rays (GCRs) during the deep solar minimum, including the declining phase, of solar cycle 23 and compare the results of this unusual period with the results obtained during similar phases of the…

Solar and Stellar Astrophysics · Physics 2013-12-03 O. P. M. Aslam , Badruddin

We have used available intermediate degree p-mode frequencies for the solar cycle 23 to check the validity of previously derived empirical relations for frequency shifts (Jain et al.: 2000, Solar Phys., 192, 487). We find that the…

Astrophysics · Physics 2015-06-24 Kiran Jain , S. C. Tripathy , A. Bhatnagar

We study the connections between the sun's convection zone and the evolution of the solar wind and corona. We let the magnetic fields generated by a 2.5D axisymmetric kinematic dynamo code (STELEM) evolve in a 2.5D axisymmetric coronal…

Solar and Stellar Astrophysics · Physics 2015-05-28 Rui F. Pinto , Allan Sacha Brun , Laurène Jouve , Roland Grappin

We have analyzed the full set of SOHO/MDI f- and p-mode oscillation frequencies from 1996 to date in a search for evidence of solar radius evolution during the rising phase of the current activity cycle. Like Antia et al. (2000), we find…

Astrophysics · Physics 2009-11-06 W. A. Dziembowski , P. R. Goode , J. Schou

Variations of the weak magnetic fields of the photosphere with periods of the order of the solar magnetic cycle were investigated. Synoptic maps of the photospheric magnetic field produced by NSO Kitt Peak for the period from 1978 to 2016…

Solar and Stellar Astrophysics · Physics 2023-07-18 E. S. Vernova , M. I. Tyasto , D. G. Baranov

The solar northern and southern hemispheres exhibit differences between the intensities and time profiles of the activity cycles. The time variation of these properties has been studied in a previous article on the data of Cycles 12-23. The…

Solar and Stellar Astrophysics · Physics 2016-07-29 Judit Muraközy

Research results from solar-dynamo models show the northern and southern hemispheres may evolve separately throughout the solar cycle. The observed phase lag between the hemispheres provides information regarding the strength of hemispheric…

Solar and Stellar Astrophysics · Physics 2015-05-18 A. A. Norton , J. C. Gallagher

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

We explore the sensitivity of the frequencies of low-degree solar p-modes to near-surface magnetic flux on different spatial scales and strengths, specifically to active regions with strong magnetic fields and ephemeral regions with weak…

Solar oscillations frequencies show a distinct change with solar activity. The changes in frequencies can be used to study the time variation of solar structure. We discuss constraints on the changes in solar structure with time as obtained…

Astrophysics · Physics 2007-05-23 Sarbani Basu

The extended minimum of Solar Cycle 23, the extremely quiet solar-wind conditions prevailing, and the mini-maximum of Solar Cycle 24 drew global attention and many authors have since attempted to predict the amplitude of the upcoming Solar…

Solar and Stellar Astrophysics · Physics 2020-12-07 K. Sasikumar Raja , P. Janardhan , Susanta Kumar Bisoi , Madhusudan Ingale , Prasad Subramanian , K. Fujiki , Milan Maksimovic

We have examined how the characteristics of the tachocline -- i.e., the change in rotation rate $\delta\Omega$, or the "jump", the position of the midpoint of the tachocline, $r_d$, and the width of the tachocline, $w_d$, -- change as a…

Solar and Stellar Astrophysics · Physics 2026-03-04 Sarbani Basu , Sylvain G. Korzennik , Sushanta C. Tripathy

Apart from the 11-year solar cycle, another periodicity around 155-160 days was discovered during solar cycle 21 in high energy solar flares, and its presence in sunspot areas and strong magnetic flux has been also reported. This…

Solar and Stellar Astrophysics · Physics 2014-11-20 T. V. Zaqarashvili , M. Carbonell , R. Oliver , J. L. Ballster

We could infer a secular decreasing trend in the poloidal to toroidal solar magnetic flux amplification factor ( Af) using geomagnetic observations ( classic and IHV corrected aa indices) during the sunspot cycles 9-23. A similar decreasing…

General Physics · Physics 2010-12-23 T. E. Girish , G. Gopkumar
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