Polar faculae and sunspot cycles

Макаров, В. И.; Makarova, V. V.

doi:10.1007/bf00148001

Cited by 106 publications

(55 citation statements)

References 14 publications

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“…6), albeit less intense, thus agreeing with the faculae distribution. Second, at polar regions the number of faculae is seen to be anti-correlated with the sunspot cycle (Makarov & Makarova 1996, had already pointed out that the number of polar faculae is observed to be anti-correlated with the sunspot cycle), the same behavior was detected for the 17 GHz polar brightenings (Fig. 3).…”

Section: Discussionsupporting

confidence: 59%

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Temporal and angular variation of the solar limb brightening at 17 GHz

Selhorst

Silva

Costa

et al. 2003

A&A

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Abstract. In order to better understand the atmosphere structure of the Sun, we have analyzed over 3000 daily maps of the Sun taken at 17 GHz from the Nobeyama Radioheliograph (NoRH) from 1992 through 2001, focusing on the excess brightness temperature observed near the limb. The purpose of this work is to characterize the limb brightness in two ways: (i) study the temporal variation of the intensity and radial width of polar brightening; and (ii) measure the brightness distribution along the limb as a function of position angle and compare it with data at other wavelengths throughout the solar cycle. The mean intensity of the polar regions were found to be approximately 13% and 14% above quiet Sun levels at the North and South poles, respectively. Moreover, the polar brightenings are strongly anti-correlated with solar activity (as measured by sunspot number). The radial width of the excess brightness is slightly over 1 arcmin for both polar regions. Only a small variation with the solar cycle was observed during the decline of last maximum, that is, the Southern polar brightening was found to be both wider and brighter than the Northern one for the 23rd cycle. As for the angular variation of the limb brightening, for a month during a period of minimum activity, it reaches 25% above quiet Sun levels at the poles, ∼15% near the equator, and 10% at intermediate regions. Hα images also show brightening enhancements at the polar regions for the same period. We also found a strong anti-correlation between the radio polar brightenings and the coronal holes seen in soft X-ray images from 1992 to 2001. There seems to be a strong association of the radio limb brightening at 17 GHz with faculae. The implications of these correlations are discussed.

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Section: Discussionsupporting

confidence: 59%

“…Photographic images have shown the presence of bright faculae near the poles of the Sun (Makarov & Makarova 1996). Spicules are also observed in Hα images, being more numerous near the poles (Lippincott 1957;Rabin & Moore 1980;Pataraya et al 1990).…”

Section: Angular and Temporal Variation Of The Limb Brightnessmentioning

confidence: 97%

Temporal and angular variation of the solar limb brightening at 17 GHz

Selhorst

Silva

Costa

et al. 2003

A&A

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“…Faculae can therefore be used to estimate surface magnetic flux at the poles. For example, polar magnetic reversal times were estimated by Makarov and Makarova (1996) from observations of faculae back to 1870 (cycle 11). A continuous data set from 1906 to the present is available from MWO.…”

Section: Polar Faculaementioning

confidence: 99%

Solar Magnetism in the Polar Regions

Petrie

2015

Living Rev. Sol. Phys.

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This review describes observations of the polar magnetic fields, models for the cyclical formation and decay of these fields, and evidence of their great influence in the solar atmosphere. The polar field distribution dominates the global structure of the corona over most of the solar cycle, supplies the bulk of the interplanetary magnetic field via the polar coronal holes, and is believed to provide the seed for the creation of the activity cycle that follows. A broad observational knowledge and theoretical understanding of the polar fields is therefore an essential step towards a global view of solar and heliospheric magnetic fields. Analyses of both high-resolution and long-term synoptic observations of the polar fields are summarized. Models of global flux transport are reviewed, from the initial phenomenological and kinematic models of Babcock and Leighton to present-day attempts to produce time-dependent maps of the surface magnetic field and to explain polar field variations, including the weakness of the cycle 23 polar fields. The relevance of the polar fields to solar physics extends far beyond the surface layers from which the magnetic field measurements usually derive. As well as discussing the polar fields' role in the interior as seed fields for new solar cycles, the review follows their influence outward to the corona and heliosphere. The global coronal magnetic structure is determined by the surface magnetic flux distribution, and is dominated on large scales by the polar fields. We discuss the observed effects of the polar fields on the coronal hole structure, and the solar wind and ejections that travel through the atmosphere. The review concludes by identifying gaps in our knowledge, and by pointing out possible future sources of improved observational information and theoretical understanding of these fields. Article RevisionsLiving Reviews supports two ways of keeping its articles up-to-date:Fast-track revision. A fast-track revision provides the author with the opportunity to add short notices of current research results, trends and developments, or important publications to the article. A fast-track revision is refereed by the responsible subject editor. If an article has undergone a fast-track revision, a summary of changes will be listed here.Major update. A major update will include substantial changes and additions and is subject to full external refereeing. It is published with a new publication number.For detailed documentation of an article's evolution, please refer to the history document of the article's online version at http://dx

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“…The polar magnetic field can be understood as the net field transported to the polar zones from the sunspot activity belts by surface flux transport (Cameron et al 2010) and forms from the sources both in the preceding and the current activity cycle (Tlatov 2007(Tlatov , 2009. PF are also closely related with both the large-and small-scale magnetic field structures (Erofeev & Erofeeva 2000;Makarov & Makarova 1996). The origin of solar magnetic field at high latitudes is very complex, we should pay more attention to the solar activity at polar zones in future.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Polar faculae (PF), considered as the main index of high-latitude solar activity, are in anti-phase with sunspot numbers (SNs) (Sheeley 1991(Sheeley , 2008Makarov & Makarova 1996;Li et al 2002;Deng et al 2011). As PF and SNs represent poloidal magnetic field and toroidal magnetic field respectively, their phase relation is of interest by means of different points of view (Hagino et al 2004;Callebaut & Makarova 2008), but it is still poorly investigated.…”

Section: Introductionmentioning

confidence: 99%

Phase relationship between polar faculae and sunspot numbers

2012

Proc. IAU

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Abstract. Linear and nonlinear approaches are used to investigate the phase asynchrony between the polar faculae (PF) and sunspot numbers (SNs). It is found that, (1) PF show leads of 52 months relative to SNs on the average of the considered time interval; (2) the crosswavelet transform analysis shows that they are asynchronous in both the low-and high-frequency components. These indicate that their phase relationship is not only time-dependent but also frequency-dependent.

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Polar faculae and sunspot cycles

Cited by 106 publications

References 14 publications

Temporal and angular variation of the solar limb brightening at 17 GHz

Temporal and angular variation of the solar limb brightening at 17 GHz

Solar Magnetism in the Polar Regions

Phase relationship between polar faculae and sunspot numbers

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