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We examine continuous measurements of the high-degree acoustic mode frequencies of the Sun covering the period from 2001 July to June 2014. These are obtained through the ring-diagram technique applied to the full-disk Doppler observations…

Solar and Stellar Astrophysics · Physics 2015-10-14 S. C. Tripathy , K. Jain , F. Hill

Solar oscillation frequencies change with the level of magnetic activity. Localizing subsurface magnetic field concentrations in the Sun with helioseismology will help us to understand the solar dynamo. Because the magnetic fields are not…

Solar and Stellar Astrophysics · Physics 2018-02-28 René Kiefer , Markus Roth

Magnetic activity changes the gravito-acoustic modes of solar-like stars and in particular their frequencies. There is an angular-degree dependence that is believed to be caused by the non-spherical nature of the magnetic activity in the…

Solar and Stellar Astrophysics · Physics 2019-06-26 F. Perez Hernandez , R. A. Garcia , S. Mathur , A. R. G. Santos , C. Regulo

Parker Solar Probe and Solar Orbiter data are used to investigate the radial evolution of magnetic turbulence between $0.06 ~ \lesssim R ~\lesssim 1$ au. The spectrum is studied as a function of scale, normalized to the ion inertial scale…

We report on the changes of the Sun's subsurface stratification inferred from helioseismology data. Using SOHO/MDI (SOlar and Heliospheric Observatory/Michelson Doppler Imager) data for the last 9 years and, more precisely, the temporal…

Astrophysics · Physics 2009-11-13 Sandrine Lefebvre , Alexander Kosovichev

The oscillations of the solar-like star HD 49933 have been observed thoroughly by CoRot. Two dozens of frequency shifts, which are closely related with the change in magnetic activity, have been measured. To explore the effects of the…

Solar and Stellar Astrophysics · Physics 2015-06-18 Zhie Liu , Shaolan Bi , Wuming Yang , Tanda Li , Kang Liu , Zhijia Tian , Zhishuai Ge , Jie Yu

We study variations of the lifetimes of high-degree solar p-modes in the quiet and active Sun with the solar activity cycle. The lifetimes in the degree range 300 - 600 and frequency 2.5 - 4.5 mHz were computed from SOHO/MDI data in an area…

Solar and Stellar Astrophysics · Physics 2009-06-21 O. Burtseva , F. Hill , S. Kholikov , D. -Y. Chou

The total solar irradiance (TSI) varies on timescales of minute to centuries. On short timescales it varies due to the superposition of intensity fluctuations produced by turbulent convection and acoustic oscillations. On longer scale…

Solar and Stellar Astrophysics · Physics 2022-10-12 V. Penza , F. Berrilli , L. Bertello , M. Cantoresi , S. Criscuoli , P. Giobbi

We analyze magnetic field data from the first six encounters of PSP, three Helios fast streams and two Ulysses south polar passes covering heliocentric distances $0.1\lesssim R\lesssim 3$ au. We use this data set to statistically determine…

Solar and Stellar Astrophysics · Physics 2021-10-13 Anna Tenerani , Nikos Sioulas , Lorenzo Matteini , Olga Panasenco , Chen Shi , Marco Velli

After decades of effort, the solar activity cycle is exceptionally well characterized but it remains poorly understood. Pioneering work at the Mount Wilson Observatory demonstrated that other sun-like stars also show regular activity…

Solar and Stellar Astrophysics · Physics 2017-09-01 Travis S. Metcalfe , Jennifer van Saders

In this Letter we present a seismological detection of a rising motion of magnetic flux in the shallow convection zone of the Sun, and show estimates of the emerging speed and its decelerating nature. In order to evaluate the speed of…

Solar and Stellar Astrophysics · Physics 2015-06-15 Shin Toriumi , Stathis Ilonidis , Takashi Sekii , Takaaki Yokoyama

The solar magnetic activity consists of two periodic components: the main cycle with a period of 11 yr and a shorter cycle with a period of ~2 yrs. The origin of this second periodicity is still not well understood. We use almost 15 yrs of…

Solar and Stellar Astrophysics · Physics 2015-06-11 R. Simoniello , K. Jain , S. C. Tripathy , S. Turck-Chieze , W. Finsterle , M. Roth

Aims. The Sun shows strong variability in its magnetic activity, from Grand minima to Grand maxima, but the nature of the variability is not fully understood, mostly because of the insufficient length of the directly observed solar activity…

Solar and Stellar Astrophysics · Physics 2014-02-24 I. G. Usoskin , G. Hulot , Y. Gallet , R. Roth , A. Licht , F. Joos , G. A. Kovaltsov , E. Thebault , A. Khokhlov

We derive formulae connecting the frequency variations in the spectrum of solar oscillations to the dynamical quantities that are expected to change over the solar activity cycle. This is done for both centroids and the asymmetric part of…

Astrophysics · Physics 2009-11-10 W. A. Dziembowski , P. R. Goode

We analyze intermediate degree p- and f-mode eigenfrequencies measured by GONG and MDI/SOHO for a complete solar cycle to study their correlation with solar activity. We demonstrate that the frequencies do vary linearly with the activity,…

Solar and Stellar Astrophysics · Physics 2009-02-11 Kiran Jain , S. C. Tripathy , F. Hill

The Parker Solar Probe mission provides a unique opportunity to characterize several features of the solar wind at different heliocentric distances. Recent findings have shown a transition in the inertial range spectral and scaling…

Solar and Stellar Astrophysics · Physics 2022-11-30 Tommaso Alberti , Simone Benella , Giuseppe Consolini , Mirko Stumpo , Roberto Benzi

We examine the frequency shifts in low-degree helioseismic modes from the Birmingham Solar-Oscillations Network (BiSON) covering the period from 1985 - 2016, and compare them with a number of global activity proxies well as a…

Solar and Stellar Astrophysics · Physics 2017-07-26 R. Howe , G. R. Davies , W. J. Chaplin , Y. Elsworth , S. Basu , S. J. Hale , W. H. Ball , R. W. Komm

Solar activity has significantly changed over the last two Schwabe cycles. After a long and deep minimum at the end of Cycle 23, the weaker activity of Cycle 24 contrasts with the previous cycles. In this work, the response of the solar…

Solar and Stellar Astrophysics · Physics 2015-06-24 D. Salabert , R. A. Garcia , S. Turck-Chieze

The power spectrum of the evolving solar wind shows evidence of a spectral break between an inertial range of turbulent fluctuations at higher frequencies and a "$1/f$" like region at lower frequencies. In the ecliptic plane at $\sim 1$ AU,…

Solar and Stellar Astrophysics · Physics 2009-09-24 R. M. Nicol , S. C. Chapman , R. O. Dendy

The Sun shrinks during solar maximum and regrows during solar minimum by a few kilometers. Here, we observe, for the first time, that the solar radius variation shows planetary relationship. This suggests that some remote planetary links…

General Physics · Physics 2022-02-10 Konstantin Zioutas , Marios Maroudas , Alexander Kosovichev