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1.
The mean photospheric magnetic field of the sun seen as a star has been compared with the interplanetary magnetic field observed with spacecraft near the earth. Each change in polarity of the mean solar field is followed about 4 1/2 days later by a change in polarity of the interplanetary field (sector boundary). The scaling of the field magnitude from sun to near earth is within a factor of two of the theoretical value, indicating that large areas on the sun have the same predominant polarity as that of the interplanetary sector pattern. An independent determination of the zero level of the solar magnetograph has yielded a value of 0.1±0.05 G. An effect attributed to a delay of approximately one solar rotation between the appearance of a new photospheric magnetic feature and the resulting change in the interplanetary field is observed.  相似文献   

2.
The spatial organization of the observed photospheric magnetic field, as well as its relation to the polarity of the interplanetary field, have been studied using high resolution magnetograms from Kitt Peak National Observatory. Systematic patterns in the large scale field have been found to be due to contributions from both concentrated flux and more diffuse flux. It is not necessary to assume, as has often been done in previous studies, that there is a weak background solar magnetic field causing the large-scale patterns in the photosphere, although the existence of such a field cannot be excluded. The largest scale structures in the photosphere correspond to the expected pattern at the base of a warped heliomagnetic equator.The polarity of the photospheric field, determined on various spatial scales, correlates with the polarity of the interplanetary field, with the most significant correlation due to mid-latitude fields. However, because the interplanetary field is likely to be rooted in concentrated photospheric regions, rather than across an entire polarity region, both the strength and polarity of the field are important in determining the interplanetary field. Thus studies of the interplanetary field which are based on either instrumental or numerical averaging of fields in the solar photosphere are subject to serious inherent limitations.Analyses based on several spatial scales in the photosphere suggest that new flux in the interplanetary medium is often due to relatively small photospheric features which appear in the photosphere up to one month before they are manifest at the Earth. The evolution of the over-all photospheric pattern may be due to individual sub-patterns which have slightly different rotation properties and which alternate in their relative dominance of the interplanetary medium.  相似文献   

3.
A solar telescope has been built at Stanford University to study the organization and evolution of large-scale solar magnetic fields and velocities. The observations are made using a Babcock-type magnetograph which is connected to a 22.9 m vertical Littrow spectrograph. Sun-as-a-star integrated light measurements of the mean solar magnetic field have been made daily since May 1975. The typical mean field magnitude has been about 0.15 G with typical measurement error less than 0.05 G. The mean field polarity pattern is essentially identical to the interplanetary magnetic field sector structure (see near the Earth with a 4 day lag). The differences in the observed structures can be understood in terms of a warped current sheet model.  相似文献   

4.
A comparison is made of observational data on the mean magnetic field of the Sun from several observatories (a selection of published information and new measurements). Results of correlation and regression analyses of observations of background magnetic fields at the STOP telescope of the Sayan solar observatory in different spectral lines are also presented. Results obtained furnish an opportunity to obtain more unbiased information about largescale magnetic fields of the Sun and, in particular, about manifestations of strong (kilogauss) magnetic fields in them.  相似文献   

5.
L. A. Plyusnina 《Solar physics》1985,102(1-2):191-201
For the period 1969–1975, a study has been made of the dependence of the interplanetary magnetic field structure on the distribution and evolutionary properties of solar magnetic fields. By direct comparison of a sequence of synoptic charts of the photospheric magnetic field with the interplanetary magnetic field, and by applying the method of correlation analysis, it is shown that to areas with an unstable polarity of the interplanetary magnetic field there correspond regions with a complicated inverse polarity line that forms either narrow gulfs and islands against a background of the dominant polarity, or bipolar magnetic regions and their clusters. At the time of reconstruction of the photospheric magnetic field the correlation between the photospheric and interplanetary magnetic field element distributions worsens. An asymmetry of the correlation between the interplanetary and photospheric magnetic field structures of different hemispheres is found. During the period of study, the interplanetary field structure shows a better correlation with the distribution of the photospheric magnetic field at middle and lower latitudes (0°–40°) of the southern hemisphere.  相似文献   

6.
A simple model is used to present a unified picture of the polarity pattern of the interplanetary magnetic field observed during the solar cycle. Emphasis in this paper is on the field near solar maximum. The heliographic latitude dependence of the dominant polarity of the interplanetary magnetic field is explained in terms of weak poloidal (dipolar) field sources in the sun's photosphere. Unlike the Babcock theory, the author hypothesizes that the dipolar field exists at equatorial latitudes (0–20°), too, (as well as in polar regions) and that the major source of the interplanetary magnetic field observed near the ecliptic plane is the dipolar field from equatorial latitudes. The polarity of the interplanetary field data taken in 1968 and in the first half of 1969 near solar maximum may possibly be explained in terms of a depression of the dipolar field boundary in space. The effect on the solar wind of the greater activity in the northern hemisphere of the sun that existed in 1968 and in the first half of 1969 is believed responsible for this hypothesized depression, especially near solar maximum, of the plane separating the + and - dipolar polarity below the solar equatorial plane in space. Predictions are made concerning the interplanetary field to be observed near the ecliptic plane in each portion of the next solar cycle.  相似文献   

7.
The sector polarity of the interplanetary magnetic field has been inferred daily for the period 1971–1973, using ground level cosmic ray observations. The method depends on the sectors directed towards and away from the Sun being associated with different characteristic variations of the cosmic ray north-south asymmetry. The analysis has a simple basis. The difference between the north and south daily mean intensities of directional telescopes at a single observing station is determined and its value relative to the 27-day average is calculated. The sign (negative or positive) of the value thus derived corresponds to the sector polarity on a daily basis. Good (~76%) agreement is obtained between the polarities inferred indirectly by the present method and those observed directly with the spacecraft magnetometers. We therefore suggest that cosmic ray observations can be used for inferring the sector polarity of the magnetic field in interplanetary space.  相似文献   

8.
A study of the predominant interplanetary magnetic field (IMF) polarity is made, for the time period 1957–1977. The examination of the mean positive and negative sector width for time periods (semesters) for which the Earth was in northern and southern heliolatitudes shows that the predominant polarity for every semester follows, up to a certain extent, the Rosenberg-Coleman effect. However, the statistical support is not satisfactory. The same conclusion was pointed out by a similar study of data grouped over various phases of the solar cycle.Additionally the relative frequency of positive (negative) IMF polarity days, appeared over a mean solar rotation, shows that the general pattern of the mean IMF has a tendency to reoccur in the homologous (corresponding) phases of different solar cycles.  相似文献   

9.
Significant discrepancies are often observed among the values of the mean magnetic field (MMF) of the Sun as a star observed by various instruments using various spectral lines. This is conventionally attributed to the measurement errors and “saturation” of a solar magnetograph in fine-structure photospheric elements with a strong magnetic field. Measurements of the longitudinal MMF performed in 1968–2006 at six observatories are compared in this paper. It is shown that the degree of discrepancy (slopes b of linear regression lines) varies significantly over the phase of the 11-year cycle. This gives rise to a paradox: the magnetograph calibration is affected by the state of the Sun itself. The proposed explanation is based on quantum properties of light, namely, nonlocality and “coupling” of photons whose polarization at the telescope-spectrograph output is determined by spacious parts of the solar disk. In this case, the degree of coupling, or “identity,” of photons depends on the field distribution in the photosphere and the instrument design (as Bohr said, “the instrument inevitably affects the result”). The “puzzling” values of slope b are readily explained by the dependence of the coupling on the solar-cycle phase. The very statistical nature of light makes discrepancies unavoidable and requires the simple averaging of data to obtain the best approximation of the actual MMF. A 39-year time series of the MMF absolute value is presented, which is indicative of significant variations in the magnitude of the solar magnetic field with a cycle period of 10.5(7) yr.  相似文献   

10.
Data from the two HEOS satellites obtained during the period December 1968 to August 1974 are used to investigate the large-scale properties of the interplanetary magnetic field.The sector structure has been deduced from the observed times of sector boundary crossings which are tabulated. A two-sector pattern existed throughout most of the period with occasional intervals of 2–3 months duration in which four sectors appeared. The variation of the dominant sector polarity with heliographic latitude showed a reversal in sense during 1971 at the time of the reported reversal in the Sun's polar field. A statistical analysis of the change in polarity distribution with latitude suggests that at Earth's orbit the sector boundaries are inclined to the solar equator on average at an angle of 12 deg.No evidence was found in the HEOS measurements of the north-south field component to confirm the systematic latitude-dependent deviation of the plasma flow away from the solar equatorial plane suggested by several analyses of data from previous spacecraft. The mean field magnitude and the average amplitude of the directional fluctuations appeared to be independent of heliographic latitude within the ±7.3° range explored.  相似文献   

11.
It has been found that photospheric magnetic fields can change in accordance with restructuring of the three-dimensional magnetic field following solar eruptions.Previous studies mainly use vector magnetic field data taken for events near the disk center.In this paper,we analyze the magnetic field evolution associated with the 2012 October 23 X1.8 flare in NOAA AR 11598 that is close to the solar limb,using both the 45 s cadence line-of-sight and 12 min cadence vector magnetograms from the Helioseismic and Magnetic Imager on board Solar Dynamics Observatory.This flare is classified as a circular-ribbon flare with spine-fan type magnetic topology containing a null point.In the line-of-sight magnetograms,there are two apparent polarity inversion lines(PILs).The PIL closer to the limb is affected more by the projection effect.Between these two PILs there lie positive polarity magnetic fields,which are surrounded by negative polarity fields outside the PILs.We find that after the flare,both the apparent limb-ward and disk-ward negative fluxes decrease,while the positive flux in-between increases.We also find that the horizontal magnetic fields have a significant increase along the disk-ward PIL,but in the surrounding area,they decrease.Synthesizing the observed field changes,we conclude that the magnetic fields collapse toward the surface above the disk-ward PIL as depicted in the coronal implosion scenario,while the peripheral field turns to a more vertical configuration after the flare.We also suggest that this event is an asymmetric circular-ribbon flare:a flux rope is likely present above the disk-ward PIL.Its eruption causes instability of the entire fan-spine structure and the implosion near that PIL.  相似文献   

12.
S. Latushko 《Solar physics》1996,166(2):261-266
A study is made of the rotation of large-scale magnetic fields using the synoptic maps from the Kitt Peak National Observatory for the time interval 1976–1985. The auto-correlation method and the mass-centers method of magnetic structures was applied to infer mean differential rotation profiles and rotation profiles separately for each magnetic field polarity. It has been found that in both hemispheres the leading polarity rotates faster than the following polarity at all latitudes by about 0.04° day–1. The maximum rotation rate of the leading polarity is reached at about 6° latitude. In the mean profile for both polarities, this brings about two angular velocity maxima at 6° latitudes in both hemispheres. Such a profile appears as to have a dimple on the equator.  相似文献   

13.
A noise storm center clearly associated to an active center has been followed from January 2 to January 8, 1969. The study of the mean distribution of continuum and of type 1 bursts has shown a global and systematic displacement interpreted in terms of the coronal magnetic structure. This structure is formed by field lines connecting the active center to a stable region of inverse polarity, characterized by the existence of a coronal condensation. These results show the possibility of using this method for the systematic study of coronal magnetic structures, the knowledge of which is vital as far as the problems of particle propagation in the corona and in the interplanetary medium are concerned.  相似文献   

14.
Our investigation has been carried using the instruments onboard the Solar Dynamics Observatory (SDO) providing a high resolution of images (AIA photographs and HMI magnetograms). We have investigated the structure and magnetic evolution of several coronal bright points and small scale N-S polarity magnetic fluxes closely associated with them. We also compare the evolution of the magnetic polarities of elementary isolated sources of positive and negative fluxes (magnetic bipoles) and coronal bright points. Tiny (“elementary”) coronal bright points have been detected. A standard coronal bright point is shown to be a group of “elementary” coronal bright points that flare up sequentially. Our investigation shows that a change in the magnetic fluxes of opposite polarities is observed before the flare of a coronal bright point. We show that not all cases of the formation of coronal bright points are described by the magnetic reconnection model. This result has not been considered previously and has not been pointed out by other authors.  相似文献   

15.
Measurements of the polar magnetic fields of the sun made in August 1968 with the Crimean and Mt Wilson magnetographs are compared. The agreement between the results obtained at the two observatories is rather satisfactory. The correlation coefficient between the Crimean and Mt Wilson values of the observed average field strength at different latitudes is 0.7 for the north and 0.5 for the south polar region. The earlier conclusion based on the Mt Wilson material that a polarity reversal of the field occurred at latitudes +70° and -55° in the north and south hemispheres (Stenflo, 1970) is confirmed by the Crimean data.  相似文献   

16.
A comparison has been made between the predictions of the theory for radial variations of both Alfvénic fluctuations and solar wind proton temperatures proposed by Tu (1987, 1988) and the statistical results of hourly averaged plasma and magnetic field data observed by Helios 1 and 2 from launch through 1980 for different solar wind speed regimes. The comparison shows that for speed ranges between 500–800 km s-1, the radial variation of the proton temperature between 0.3 and 1 AU can be explained by heating from the cascade energy determined by the radial variation of the total variance of magnetic field vector. The explanation of the radial variations of both temperature and the total variance of magnetic fields for speed ranges less than 400 km s -1 is less clear.This project was supported by National Natural Science Foundation of China for Tu's part of the work.  相似文献   

17.
The mean magnetic field (MMF) of the photosphere of the Sun as a star was measured in 2001?C2010 at the Crimean Astrophysical Observatory using two Fe I absorption lines with ?? = 524.7 nm and ?? = 525.0 nm. The regression coefficient b for 1054 pairs of daily values measured simultaneously on both lines equals 0.82 (a correlation coefficient is 0.94; magnetic field strengths determined by the line with ?? = 525.0 nm are lower than those for the line with ?? = 524.7 nm). However, the b value varied significantly along with phases of the 11-year cycle from 0.88 in 2003 to 0.49 in 2009. It is difficult to ascribe these variations to purely instrumental or solar causes. Moreover, the semiannual value of b decreased with the decrease in the absolute strength of the MMF, which contradicts the model of thin magnetic flux ropes of the photosphere. Similar behavior of b was also observed in the comparison of MMF measured at the Crimean Astrophysical Observatory and Stanford by the line with ?? = 525.0 nm. The inconsistency of the results obtained by these two iron lines on different instruments has been noted. It has been concluded that the variance in and odd behavior of b are predetermined not only by the instrument and the Sun (by the so-called fine structure of the photosphere field), but also by the act of measuring. When recording solar (and stellar) magnetic fields and modeling atmospheric processes, quantum effects have to be taken into account, such as nonlocality, indistinguishability, and the entanglement of photons, as well as that a photon only acquires its properties at the exact moment of its detection. The best approximation to reality can be achieved by averaging the MMF measurements carried out with different magnetographs and in different spectral lines.  相似文献   

18.
The evolution of the background magnetic field with the solar cycle has been studied using the dipole-quadrupole magnetic energy behaviour in a cycle. The combined energy of the axisymmetric dipole, non-axisymmetric quadrupole, and equatorial dipole is relatively lowly variable over the solar cycle. The dipole field changed sign when the quadrupole field was near a maximum, andvice versa. A conceptual picture involving four meridional magnetic polarity sectors proposed to explain these features may be in agreement with equatorial coronal hole observations. The rate of sector rotation is estimated to be 8 heliographic degrees per year faster than the Carrington rotation (P = 27.23d synodic). Polarity boundaries of sectors located 180° apart show meridional migrations in one direction, while the boundaries of the other two sectors move in the opposite direction. A simple model of how the magnetic field energy varies, subject to specifying reasonable initial photospheric magnetic and velocity field patterns, follows the observed evolution of the dipole and quadrupole field energies quite nicely.  相似文献   

19.
Analysis of observations of the white-light corona performed aboard OSO-7 is evidence for the existence of coronal ribbon-structures, which may be observed on the limb as coronal streamers. It is shown that prolongation of these structures into interplanetary space forms a curved surface; intersection of this surface is accompanied by a change of polarity of the interplanetary magnetic field, which existed in May–July 1973; and its connection with several phenomena in the solar atmosphere, has been found.  相似文献   

20.
The small-scale (～10″) stochastic properties of the solar magnetic field B are analyzed in terms of the two-dimensional model of a fractal Brownian process (the mean square of the difference between the field strengths at two points separated by a distance D is proportional to D 2H ). Digitized solar magnetograms with a 2″ resolution are used to determine the standard deviation s of the magnetic field and the exponents H at various levels of |B|. It has been established that the transition from the background magnetic field to the fields of an active region occurs near 25–50 G. A dependence of the exponent H on the magnetic field amplitude has been derived. The exponent H for the background magnetic field has been found to be much smaller than that for the fields of an active region. The relationship of the results obtained to certain fundamental properties of plasma in a magnetic field is discussed.  相似文献   

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