共查询到20条相似文献，搜索用时 62 毫秒
1.
V. E. Abramov-Maximov V. I. Efremov L. D. Parfinenko A. A. Solov’ev K. Shibasaki 《Geomagnetism and Aeronomy》2013,53(7):909-912
An analysis of oscillatory processes with periods not shorter than several tens of minutes in three isolated sunspots, which were observed during identical periods in the optical and radio bands, is illustrated. SDO/HMI magnetograms at an interval of 45 s and radio maps at a wavelength of 1.76 cm, obtained using a Nobeyama radioheliograph (NoRH), have been used. The time profiles, which were constructed based on the NoRH and SDO/HMI data, indicate that the oscillations of the radioemission correlate with those of the sunspot magnetic field. The wavelet spectra and cross-wavelet transform reveal common oscillation periods of 30–40, 70–100, and 150–200 min. The identical oscillation periods, found using fundamentally different methods from ground-based and space observations, confirm the solar nature of these oscillations, which can be interpreted as oscillations of a sunspot as a whole. 相似文献
2.
Babin A. N. Koval’ A. N. Tsap Yu. T. Borisenko A. V. 《Geomagnetism and Aeronomy》2018,58(8):1149-1158
This paper examines the evolution and morphology of a magnetic anomaly: the appearance and disappearance of a longitudinal magnetic flux with opposite polarity at an area of about 10 arc seconds in the umbra of the following sunspot of an NOAA 12192 active region, which was observed from 21 to 26 October 2014 in the SDO/HMI and SOLIS/VSM magnetograms. Information collected by spacecraft and under on-ground observations including data from the Sun Service of the Crimean Astrophysical Observatory of the Russian Academy of Sciences are analyzed. Based on the methods of observation and determination of longitudinal magnetic fields in SDO/HMI in line FeI 6173.34 Å it was revealed, that combinations of contours appearing due to magnetic force lines inclinations relative to the line-of-sight and line-of-sight velocities can cause a significant undervalue of the magnetic field intensity in magnetograms, but polarity does not reverse. The fine spatial structure, evolution features, close correlation with ultraviolet loops system in SDO/AIA images, “moustaches”, and no temporal and spatial correlation with flares point to a connection between the detected anomaly and the new magnetic flux emergence of opposite polarity in a spot’s umbra at an earlier decay stage. We analyze magnetic force lines reconnection and show that annigilation of the magnetic fields of opposite polarities can take place for many hours at small (~30 km) scales and this fact is verified by observation results. There are additional facts in favor of the cluster model of a solar spot by Severny-Parker.
相似文献3.
It is shown that long-period (T = 10?C20 h) oscillations of the magnetic field in sunspots, combined in bipolar groups, are excited synchronously in the main and tail spots of a group. At the same time, there is no correlation between long-period oscillations of the field of sunspots which are in different active regions, i.e., spaced sunspots oscillate independently. This fact eliminates the question about the apparatus nature of the oscillations of interest (if there is an artifact, oscillations of all sunspots on the visible solar hemisphere would be synchronous!). High-resolution (0.5 angular seconds per pixel) MDI(SOHO) data show a high correlation between long-period oscillations of the magnetic field at isolated points of the sunspot shadow. This points to the fact that the sunspot shadow participates in long-period oscillations as a quite integral physical formation. 相似文献
4.
Long-period oscillations of the magnetic field and the line-of-sight velocity have been detected in sunspots based on the synchronous 90-h time series of magnetograms and dopplergrams obtained with the MDI(SOHO) device. The sunspot eigenmode (12–30 h), the periods of which nonlinearly depend on the magnetic field strength, predominates in the magnetic field oscillation spectrum. The mode, which is probably induced by motions of supergranulation cells (33 h), predominates in the sunspot line-of-sight velocity oscillation spectrum. A strong mode (33 h), which indicates that long-period quasi-oscillations of supergranulation exist, was also detected in the velocity power spectrum for a quiet photosphere, together with the known 5-min mode. 相似文献
5.
Field variations in the region of the eruptive event on June 7, 2011 are studied based on vector measurements of the photospheric magnetic field by the SDO/HMI instrument. Variations of the modulus (B), the radial (Br) and the transverse (Bt) components of the magnetic induction, and the inclination angle (α) of the field lines to the radial direction from the center of the Sun are analyzed. It is found that, in the part of the flare region near the polarity inversion line (PIL) after the onset of the flare, the magnitude and the transverse component of the magnetic induction as well as the angles α abruptly increase. During the slow rise of filament near its channel, the inclination angles of the field lines decrease. It is shown that diverging flare ribbons are above the regions of the photosphere with local maxima of the field modulus and with deep minima of the inclination angles of the field lines at all stages of their existence over their entire length with the exception of small areas. It is established that the azimuth decreases after the onset of the flare near the PIL of the photospheric magnetic field, which means an increase in the shear. On the contrary, at a distance from the PIL there is a slight decrease in the shear.
相似文献6.
V. G. Fainshtein Ya. I. Egorov G. V. Rudenko S. A. Anfinogentov 《Geomagnetism and Aeronomy》2016,56(8):1060-1067
Field variations in the region of eruptive event of June 7, 2011, associated with the filament eruption (FE), flare, and coronal mass ejection are studied based on vector measurements of the photospheric magnetic field with the SDO/HMI instrument. Variations of the module (B), the radial (Br) and transverse (Bt) components of the magnetic induction, and the inclination angle (α) of field lines to the radial direction from the center of the Sun are analyzed. It is shown that the strongest changes of the field before the event were located near the base of the southeastern leg of the eruptive filament; after the beginning of the event, they were located in the CME flare region. It is suggested that the FE is associated with two episodes of strong and rapid field variations: before the beginning of the slow filament rise and before its sudden acceleration. For the first time, variations of the inclination angles of the field lines over time in different parts of the eruptive event are studied in detail. It was found that the inclination angles of the field lines decrease in the vicinity of its channel during the slow rise of the filament, and the inclination angles of the field lines increase sharply after the beginning of the flare in the flare region in the vicinity of the neutral line. 相似文献
7.
The work is devoted to the study of the oscillation properties of the magnetic and velocity fields of sunspots with typical periods of up to about 104 min. These oscillations were revealed at the beginning of the 1980s (Gopasyuk, 1981) but remain understudied. Using SOHO MDI data and a technique that allows for measurements of magnetic field H and the heliographic coordinates of sunspots φ and λ with higher accuracy than direct measurements of individual pixels, we have studied 72 sunspots observed on the Sun’s visible hemisphere during no less than 9–11 days (±60–70° from the central meridian) with a time resolution of 1 min. Estimates of random errors of a measurement give σ H ≈ 60 Gs, σφ ≈ 0.055°, and σλ ≈ 0.050°. It is found that the main periods of the maximum superlong-period oscillations of sunspots are equal to eight days, according to earlier ground-based measurements. Space observations allow the effect of the Earth’s atmosphere to be totally eliminated; therefore, on the basis of recent data, one can conclude that long-period oscillations of sunspot parameters are a real Sun phenomenon. 相似文献
8.
Geomagnetism and Aeronomy - Data from observations of the photospheric magnetic field at a number of ground stations (STOP, WSO, GONG) and by the SDO/HMI satellite for 2014–2019 are examined... 相似文献
9.
E. E. Benevolenskaya 《Geomagnetism and Aeronomy》2013,53(7):891-895
The solar polar magnetic field has attracted the attention of researchers since the polar magnetic field reversal was revealed in the middle of the last century (Babcock and Livingston, 1958). The polar magnetic field has regularly reversed because the magnetic flux is transported from the sunspot formation zone owing to differential rotation, meridional circulation, and turbulent diffusion. However, modeling of these processes leads to ambiguous conclusions, as a result of which it is sometimes unclear whether a transport model is actual. Thus, according to the last Hinode data, the problem of a standard transport model (Shiota et al., 2012) consists in that a decrease in the polar magnetic flux in the Southern Hemisphere lags behind such a decrease in the flux in the Northern Hemisphere (from 2008 to June 2012). On the other hand, Svalgaard and Kamide (2012) consider that the asymmetry in the sign reversal simply results from the asymmetry in the emerging flux in the sunspot formation region. A detailed study of the polar magnetic flux evolution according to the Solar Dynamics Observatory (SDO) data for May 2010–December 2012 is illustrated in the present work. Helioseismic & Magnetic Imager (HMI) magnetic data in the form of a magnetic field component along the line of sight (the time resolution is 720 s) are used here. The magnetic fluxes in sunspot formation regions and at high latitudes have been compared. 相似文献
10.
P. V. Strekalova Yu. A. Nagovitsyn A. Riehokainen V. V. Smirnova 《Geomagnetism and Aeronomy》2016,56(8):1052-1059
Thirty small-scale structures in the solar atmosphere, i.e., facula nodes at ±(20°–46°) latitudes, have been studied in order to analyze quasi-periodic variations in the magnetic field. SDO/HMI magnetograms have been used for this purpose. Long-period variations in the magnetic field strength of the considered objects in the 60–280 min range have been revealed as a result of data processing. It has been shown that there are no dependences between the magnetic field and period, nor between the magnetic field and object area. It has been assumed that the discovered variations are not natural oscillations of the magnetic field strength. 相似文献
11.
The distribution maps of the circular polarization degree and radio brightness have been analyzed for more than 40 flares based on the Nobeyama Radioheliograph data. It has been shown that the observed microwave emission is polarized in the ordinary mode in some flaring loop parts in six events. Based on a joint analysis of the photospheric magnetic field maps obtained from the HMI/SDO and MDI/SOHO magnetograph’s and the radio emission dynamics in different source parts, it has been concluded that the ordinary mode predominance in all six selected events can be connected with implementation of the longitudinal pitch-angle anisotropy of emitting electrons. 相似文献
12.
L. I. Shestakova B. I. Demchenko F. K. Rspaev A. Chalabaev 《Geomagnetism and Aeronomy》2011,51(8):1054-1057
The results of interferometer observations of the dust radial velocity field in the F-corona during the total solar eclipse
of March 29, 2006, are presented. The observations were performed in the Mugalzhar settlement, Aqtobe region, Kazakhstan.
The observation results indicated that the dust orbital motion is opposite to the planetary motion and is inclined at an angle
of about 105° with respect to the ecliptic plane. It is assumed that the observed dust is genetically related to Kreutz comets
falling on the Sun and registered with the SOHO spacecraft on March 28 and 31, 2006. 相似文献
13.
The phenomenon of long-period sunspot oscillations with periods from several tens to a thousand minutes is studied using data on the magnetic field strength and sunspot coordinates obtained based on the SOHO MDI data. It has been indicated that oscillations of the sunspot magnetic field strength are related to relative and absolute horizontal oscillation modes, as a result of which certain limitations are imposed on the interpretation of the phenomenon. 相似文献
14.
Efremov V. I. Solov’ev A. A. Parfinenko L. D. Zhivanovich I. 《Geomagnetism and Aeronomy》2020,60(8):1023-1027
Geomagnetism and Aeronomy - Changes in the umbra brightness and in the magnetic field over time should occur on long-period sunspot oscillations in accordance with Birman’s idea of inhibition... 相似文献
15.
This paper continues the cycle of authors’ works on the detection of precursors of large flares (M5 and higher classes) in active regions (ARs) of the Sun by their microwave radiation and magnetographic characteristics. Generalization of the detected precursors of strong flares can be used to develop methods for their prediction. This paper presents an analysis of the development of NOAA AR 12242, in which an X1.8 flare occurred on December 20, 2014. The analysis is based on regular multiazimuth and multiwavelength observations with the RATAN-600 radio telescope in the range 1.65–10 cm with intensity and circular polarization analysis and data from the Solar Dynamics Observatory (SDO). It was found that a new component appeared in the AR microwave radiation two days before the X-flare. It became dominant in the AR the day before the flare and significantly decreased after the flare. The use of multiazimuth observations from RATAN-600 and observations at 1.76 cm from the Nobeyama Radioheliograph made it possible to identify the radio source that appeared before the X-flare with the site of the closest convergence of opposite polarity fields near the neutral line in the AR. It was established that the X-flare occurred 20 h after the total gradient of the magnetic field of the entire region calculated from SDO/HMI data reached its maximum value. Analysis of the evolution of the microwave source that appeared before the X-flare in AR 12242 and comparison of its parameters with the parameters of other components of the AR microwave radiation showed that the new source can be classified as neutral line associated sources (NLSs), which were repeatedly detected by the RATAN-600 and other radio telescopes 1–3 days before the large flares. 相似文献
16.
17.
The ordinary mode of gyrosynchrotron radiation was identified to be predominant in some segments of flare loops in solar flares of July 19, 2012, and October 22, 2014. These events were studied by investigation of the quasi-transverse propagation effect on the observed polarization. The analysis involved reconstruction of the magnetic field topology at the linear force-free approximation based on the data of the SDO HMI space telescope and the subsequent simulation of radio emission of flare loops with the GX Simulator software package. The quasi-transverse propagation effect was established to be characteristic for both events, but its influence on the radio emission polarization at a frequency of 17 GHz was observed only in the October 22, 2014 flare. 相似文献
18.
V. K. Roldugin Yu. P. Maltsev A. A. Ostapenko A. V. Roldugin 《Geomagnetism and Aeronomy》2006,46(4):438-449
Pulsations in the electron fluxes and magnetic field on two geosynchronous satellites and at several ground-based observatories have been studied. Relativistic electron flux pulsations with a period of 6 min originated after the shock arrival from the solar wind at 0258 UT on February 11, 2000, had a regular character, and propagated from the dayside to the nightside at a velocity of about 60 deg min?1. Magnetic field oscillations on the satellites and on the Earth had a more complicated structure. Field oscillations morphologically similar to electron oscillations are observed only on one satellite in one component and at one-two ground-based stations, where a periodicity of 10–12 min was mainly observed. It is assumed that magnetic pulsations are Alfvén resonances generated by a fast magnetosonic wave. 相似文献
19.
Yu. A. Fursyak 《Geomagnetism and Aeronomy》2016,56(7):930-937
Specific features of the magnetic configuration, morphological structure, dynamics, and evolution of sunspot groups of the current (24th) cycle of solar activity with high flare activity are considered. The gradients of longitudinal magnetic fields at places of δ-configuration are calculated. The main finding is a time delay of 24–30 h between the time when the magnetic field gradient reaches a critical level of 0.1 G/km and the time when the first of powerful flares occurs in the active region. The study is based on data from the SDO and GOES-15 spacecrafts and ground-based solar telescopes (TST-2 at the Crimean Astrophysical Observatory of the Russian Academy of Sciences and the 150-foot telescope at the Mount Wilson Observatory). 相似文献
20.
The generation and evolution of the Sun’s magnetic field and other stars is usually related to the dynamo mechanism. This mechanism is based on the consideration of the joint influence of the α effect and differential rotation. Dynamo sources can be located at different depths of the convection zone and can have different intensities. Based on such a system, the dynamical system in the case of the stellar dynamo in a two-layer medium has been constructed with regard to meridional fluxes in order to model the double cycle that corresponds to the simultaneous presence of 22-year and quasi-biennial magnetic field oscillations. It has been indicated that the regime of mixed oscillations can originate because a dynamo wave moves oppositely to the meridional flows in the upper layer of the convection zone. This results in the deceleration of the toroidal field propagation and in the generation of slow oscillations. In deeper layers, the directions of a dynamo wave and meridional flows coincide with each other, as a result of which fast magnetic fields originate. Therefore, the total contribution of two oscillations with different frequencies corresponds to the appearance of quasi-biennial cycles against 22-year cycles. It has been indicated that the beating regime, which can be related to the secular oscillations of solar magnetic activity, originates in the system when the meridional flows are weak. 相似文献