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The hemispheric asymmetry of the sunspot cycle is a real feature of the Sun. However, its origin is still not well understood. Here we perform nonlinear time series analysis of the sunspot area (and number) asymmetry to explore its…

太阳与恒星天体物理 · 物理学 2022-01-19 Ratul Das , Aparup Ghosh , Bidya Binay Karak

In this paper we investigate the dependence of umbral core brightness, as well as the mean umbral and penumbral brightness on the phase of the solar cycle and on the size of the sunspot. Albregtsen & Maltby (1978) reported an increase in…

天体物理学 · 物理学 2009-11-13 S. K. Mathew , V. Martinez Pillet , S. K. Solanki , N. A. Krivova

We study the contradictory magnetic field strength distributions retrieved from independent analyses of spectropolarimetric observations in the near-infrared (1.56 micron) and in the visible (630 nm) at internetwork regions. In order to…

天体物理学 · 物理学 2009-11-13 M. J. Martinez Gonzalez , M. Collados , B. Ruiz Cobo , C. Beck

The solar magnetism is no more considered as a purely superficial phenomenon. The SoHO community has shown that the length of the solar cycle depends on the transition region between radiation and convection. Nevertheless, the internal…

The observed variability of the cosmic-ray intensity in the interplanetary space is driven by the evolution of the Sun's magnetic activity over its 11-year quasiperiodical cycle. Investigating the relationship between solar activity indices…

太阳与恒星天体物理 · 物理学 2022-10-13 Nicola Tomassetti , Bruna Bertucci , Emanuele Fiandrini

The length of the solar activity cycle fluctuates considerably. The temporal evolution of the corresponding cycle phase, that is, the deviation of the epochs of activity minima or maxima from strict periodicity, provides relevant…

太阳与恒星天体物理 · 物理学 2023-03-15 E. Weisshaar , R. H. Cameron , M. Schüssler

In this paper, we explore the evolution of sunspot latitude distribution and explore its relations with the cycle strength. With the progress of the solar cycle, the distributions in two hemispheres from mid-latitudes propagate toward the…

太阳与恒星天体物理 · 物理学 2017-12-27 Sudip Mandal , Bidya Binay Karak , Dipankar Banerjee

Previously unobservable mirror asymmetry of the solar magnetic field -- a key ingredient of the dynamo mechanism which is believed to drive the 11-year activity cycle -- has now been measured. This was achieved through systematic monitoring…

太阳与恒星天体物理 · 物理学 2015-05-14 Hongqi Zhang , T. Sakurai , A. Pevtsov , Yu Gao , Haiqing Xu , D. D. Sokoloff , K. Kuzanyan

We present independent observations of the solar-cycle variation of flows near the solar surface and at a depth of about 60 Mm, in the latitude range $\pm45^\circ$. We show that the time-varying components of the meridional flow at these…

天体物理学 · 物理学 2009-11-13 L. Gizon , M. Rempel

We study 7530 sunspot umbrae and pores measured by the Hinode Spectropolarimeter (SP) between November 2006 and November 2012. We primarily seek confirmation of the long term secular decrease in the mean magnetic field strength of sunspot…

太阳与恒星天体物理 · 物理学 2015-05-22 T. A. Schad

We have analyzed available full-disc data from the Michelson Doppler Imager (MDI) on board SoHO using the "ring diagram" technique to determine the behavior of solar meridional flows over solar cycle 23 in the outer 2% of the solar radius.…

太阳与恒星天体物理 · 物理学 2015-05-19 Sarbani Basu , H. M. Antia

We examine whether or not it is possible to derive the field strength distribution of quiet Sun internetwork regions from very high spatial resolution polarimetric observations in the visible. In particular, we consider the case of the…

天体物理学 · 物理学 2009-11-13 D. Orozco Suarez , L. R. Bellot Rubio , J. C. del Toro Iniesta

For the first time, the motion of granules (solar plasma on the surface on scales larger than 2.5 Mm) has been followed over the entire visible surface of the Sun, using SDO/HMI white-light data. Horizontal velocity fields are derived from…

太阳与恒星天体物理 · 物理学 2015-06-04 Th. Roudier , M. Rieutord , J. M. Malherbe , N. Renon , T. Berger , Z. Frank , V. Prat , L. Gizon , M. Svanda

We discuss a prediction of the solar activity on a short time-scale applying the method based on a combination of a nonlinear mean-field dynamo model and the artificial neural network. The artificial neural network which serves as a…

The photospheric magnetic field vector is continuously derived from measurements, while reconstruction of the three-dimensional (3D) coronal magnetic field requires modelling with photospheric measurements as a boundary condition. For…

太阳与恒星天体物理 · 物理学 2022-03-23 I. Chifu , B. Inhester , T. Wiegelmann

In the declining phase of the solar cycle, when the new-polarity fields of the solar poles are strengthened by the transport of same-signed magnetic flux from lower latitudes, the polar coronal holes expand and form non-axisymmetric…

太阳与恒星天体物理 · 物理学 2015-06-23 Kalevi Mursula , Renata Lukianova , Lauri Holappa

The structure of the photospheric vector magnetic field below a dark filament on the Sun is studied using the observations of the Spectro-Polarimeter attached to the Solar Optical Telescope onboard Hinode. Special attention is paid to…

太阳与恒星天体物理 · 物理学 2019-03-20 Takaaki Yokoyama , Yukio Katsukawa , Masumi Shimojo

The extensive database of high-resolution G-band images observed with the Hinode/SOT is a unique resource to derive statistical properties of pores using advanced digital image processing techniques. The study is based on two data sets: (1)…

太阳与恒星天体物理 · 物理学 2014-05-08 Meetu Verma , Carsten Denker

Surface observations indicate that the speed of the solar meridional circulation in the photosphere varies in anti-phase with the solar cycle. The current explanation for the source of this variation is that inflows into active regions…

太阳与恒星天体物理 · 物理学 2017-11-29 D. Passos , M. Miesch , G. Guerrero , P. Charbonneau

The high spatial and time resolution data obtained with SDO/AIA for the sunspot in active region NOAA 11131 on 08 December 2010 were analysed with the time-distance plot technique and the pixelised wavelet filtering method. Oscillations in…

太阳与恒星天体物理 · 物理学 2014-09-17 R. Sych , V. M. Nakariakov