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Related papers: Solar total irradiance in cycle 23

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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

Solar cycle is modeled as a forced and damped harmonic oscillator and the amplitudes, frequencies, phases and decay factors of such a harmonic oscillator are estimated by non-linear fitting the equation of sinusoidal and transient parts to…

Solar and Stellar Astrophysics · Physics 2022-04-12 K M Hiremath

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

The results of determinations of the azimuthal and meridional velocities by time-distance helioseismology from Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) from May 2010 to September 2020 at latitudes from…

Solar and Stellar Astrophysics · Physics 2021-02-26 Alexander V. Getling , Alexander G. Kosovichev , Junwei Zhao

We have used data collected by the Birmingham Solar-Oscillations Network (BiSON) to perform a helioseismic diagnosis of changes to the Sun's internal structure between four successive solar cycle minima, beginning with the minimum at the…

Solar and Stellar Astrophysics · Physics 2026-02-10 Sarbani Basu , William J. Chaplin , Rachel Howe , Yvonne Elsworth , Steven J. Hale , Eleanor Murray

$PSP$ and $SolO$ data are utilized to investigate magnetic field intermittency in the solar wind (SW). Small-scale intermittency $(20-100d_{i})$ is observed to radially strengthen when methods relying on higher-order moments are considered…

We study temporal variations in the amplitudes and widths of high-degree acoustic modes by applying the ring-diagram technique to the GONG+, MDI and HMI Dopplergrams during the declining phase of cycle 23 and rising phase of cycle 24. The…

Solar and Stellar Astrophysics · Physics 2015-06-15 Olga Burtseva , Sushant Tripathy , Richard Bogart , Kiran Jain , Rachel Howe , Frank Hill , Maria Cristina Rabello-Soares

This paper presents the analysis of 3D evolution of solar wind density turbulence and speed at various levels of solar activity between solar cycles 22 and 24. The solar wind data has been obtained from interplanetary scintillation (IPS)…

Solar and Stellar Astrophysics · Physics 2015-06-04 P. K. Manoharan

We study the response of the low-degree solar p-mode frequencies to the unusual extension of the minimum of solar surface activity since 2007. Helioseismic observations collected by the space-based, Sun-as-a-star GOLF instrument and by the…

Solar and Stellar Astrophysics · Physics 2010-05-06 D. Salabert , R. A. Garcia , P. L. Palle , S. J. Jimenez-Reyes

The Sun's axisymmetric flows, differential rotation and meridional flow, govern the dynamics of the solar magnetic cycle and variety of methods are used to measure these flows, each with its own strengths and weaknesses. Flow measurements…

Solar and Stellar Astrophysics · Physics 2021-09-08 Sushant S. Mahajan , David H. Hathaway , Andrés Muñoz-Jaramillo , Petrus C. Martens

The strength and morphology of the Sun's magnetic field evolves significantly during the solar cycle, with the overall polarity of the Sun's magnetic field reversing during the maximum of solar activity. Long-term changes are also observed…

Solar and Stellar Astrophysics · Physics 2023-11-01 Adam J. Finley , Allan Sacha Brun

We examine the temporal changes in both solar polar magnetic field (PMF) at latitudes $\ge$ $45^{\circ}$ and heliospheric magnetic field (HMF) at 1 AU during solar cycles 21--24 with emphasis on the recent activity changes after July 2015,…

Solar and Stellar Astrophysics · Physics 2020-08-05 Susanta Kumar Bisoi , P. Janardhan , S. Ananthakrishnan

Helioseismology has revealed that the angular velocity of the Sun increases with depth in the outermost 35 Mm of the Sun. Recently, we have shown that the logarithmic radial gradient ($\rm d\ln\Omega/\rm d\ln r $) in the upper 10~Mm is…

Solar and Stellar Astrophysics · Physics 2016-11-02 Atefeh Barekat , Jesper Schou , Laurent Gizon

While the quiet Sun magnetic field shows only little variation with the solar cycle, long-term variations cannot be completely ruled out from first principles. We investigate the potential effect of quiet Sun magnetism on spectral solar…

Solar and Stellar Astrophysics · Physics 2020-06-05 M. Rempel

We study the response of the low-degree, solar p-mode frequencies to the unusually extended minimum of solar surface activity since 2007. A total of 4768 days of observations collected by the space-based, Sun-as-a-star helioseismic GOLF…

Solar and Stellar Astrophysics · Physics 2015-05-13 D. Salabert , R. A. García , P. L. Pallé , S. J. Jiménez-Reyes

Using the daily Mount Wilson Doppler velocity data during 1986-1994 (solar cycle 22), we studied the short-term variations of the order of a few days to a month time scales in the solar differential rotation coefficients A-bar, B-bar and…

Solar and Stellar Astrophysics · Physics 2011-05-23 J. Javaraiah

We used long duration, high quality, unresolved (Sun-as-a star) observations collected by the ground based network BiSON and by the instruments GOLF and VIRGO on board the ESA/NASA SOHO satellite to search for solar-cycle-related changes in…

Solar and Stellar Astrophysics · Physics 2010-04-21 R. Simoniello , W. Finsterle , R. A. Garcia , D. Salabert , A. Jimenez , Y. Elsworth , H. Schunker

We report on the annual variation of quiet-time suprathermal ion composition for C through Fe using Advanced Composition Explorer (ACE)/Ultra-Low Energy Isotope Spectrometer (ULEIS) data over the energy range 0.3 MeV/nuc to 1.28 MeV/nuc…

Solar and Stellar Astrophysics · Physics 2023-07-26 B. L. Alterman , Mihir I. Desai , Maher A. Dayeh , G. M. Mason , George Ho

The minimum - maximum method, belonging to the precursor class of the solar activity forecasting methods, is based on a linear relationship between relative sunspot number in the minimum and maximum epochs of solar cycles. In the present…

Solar and Stellar Astrophysics · Physics 2022-03-23 R. Brajša , G. Verbanac , M. Bandić , A. Hanslmeier , I. Skokić , D. Sudar

Recent models of variations of the Sun's structure with the 11-year activity cycle by Sofia et al (2005) predict strong non-homologous changes of the radius of subsurface layers, due to subsurface magnetic fields and field-modulated…

Astrophysics · Physics 2009-11-13 S. Lefebvre , A. G. Kosovichev , J. P. Rozelot