The Horizontal Magnetic Flux of the Quiet‐Sun Internetwork as Observed with the<i>Hinode</i>Spectro‐Polarimeter

Lites, B. W.; Kubo, Masahito; Socas‐Navarro, H.; Berger, T.; Frank, Z.; Shine, R.; Tarbell, T. D.; Title, A. M.; Ichimoto, Kiyoshi; Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, Toshifumi; Nagata, Shinji

doi:10.1086/522922

Cited by 417 publications

(616 citation statements)

References 38 publications

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“…However, one may put forward alternative arguments in which this quiet-Sun magnetic field is the result of a global large-scale dynamo: the shredding of a large-scale magnetic field can produce a small-scale magnetic field by cascading magnetic energy to small-scales and the decay of active regions may give rise to a small-scale magnetic field (Spruit et al 1987;de Wijn et al 2005;Stenflo 2012). However, none of these arguments may necessarily be correct because the small-scale magnetic field does not show solar cycle dependence, as it does not have significant correlation with the large-scale global magnetic cycle, and it does not have much latitudinal variation (e.g., Hagenaar et al 2003;Sánchez Almeida 2003;Lites et al 2008;Lites 2011;Buehler et al 2013;Jin & Wang 2015b). Furthermore, using the MDI data set of the entire solar cycle 23, Jin et al (2011) have shown that the cyclic variation of both the number and total flux of small-scale magnetic elements in the range ∼(3-30)×10 18 Mx are anticorrelated with the sunspot number.…”

Section: Introductionmentioning

confidence: 99%

Is the Small-Scale Magnetic Field Correlated With the Dynamo Cycle?

Karak

Brandenburg

2015

ApJ

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The small-scale magnetic field is ubiquitous at the solar surface-even at high latitudes. From observations we know that this field is uncorrelated (or perhaps even weakly anticorrelated) with the global sunspot cycle. Our aim is to explore the origin, and particularly the cycle dependence, of such a phenomenon using three-dimensional dynamo simulations. We adopt a simple model of a turbulent dynamo in a shearing box driven by helically forced turbulence. Depending on the dynamo parameters, large-scale (global) and small-scale (local) dynamos can be excited independently in this model. Based on simulations in different parameter regimes, we find that, when only the large-scale dynamo is operating in the system, the small-scale magnetic field generated through shredding and tangling of the large-scale magnetic field is positively correlated with the global magnetic cycle. However, when both dynamos are operating, the small-scale field is produced from both the small-scale dynamo and the tangling of the large-scale field. In this situation, when the large-scale field is weaker than the equipartition value of the turbulence, the small-scale field is almost uncorrelated with the large-scale magnetic cycle. On the other hand, when the large-scale field is stronger than the equipartition value, we observe an anticorrelation between the smallscale field and the large-scale magnetic cycle. This anticorrelation can be interpreted as a suppression of the smallscale dynamo. Based on our studies we conclude that the observed small-scale magnetic field in the Sun is generated by the combined mechanisms of a small-scale dynamo and tangling of the large-scale field.

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Section: Introductionmentioning

confidence: 99%

Is the Small-Scale Magnetic Field Correlated With the Dynamo Cycle?

Karak

Brandenburg

2015

ApJ

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“…Cattaneo 1999, Vögler & Schüssler 2007. Turbulent dynamo action may be responsible for the smallest-scale magnetic elements observed on the solar surface (Lites et al 2008), although intranetwork magnetic elements may also result from the decay of larger magnetic regions (created by the global dynamo) through the continuous convective mixing of the solar upper layers.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Field and Convection in the Cool Supergiant Betelgeuse

Petit

Aurière

Konstantinova-Antova

et al. 2013

Lecture Notes in Physics

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We present the outcome of a highly-sensitive search for magnetic fields on the cool supergiant Betelgeuse. A time-series of six circularly-polarized spectra was obtained using the NARVAL spectropolarimeter at Télescope Bernard Lyot (Pic du Midi Observatory), between 2010 March and April. Zeeman signatures were repeatedly detected in cross-correlation profiles, corresponding to a longitudinal component of about 1 G. The time-series unveils a smooth increase of the longitudinal field from 0.5 to 1.5 G, correlated with radial velocity fluctuations. We observe a strong asymmetry of Stokes V signatures, also varying in correlation with the radial velocity. The Stokes V line profiles are red-shifted by about 9 km s −1 with respect to the Stokes I profiles, suggesting that the observed magnetic elements may be concentrated in the sinking components of the convective flows.

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“…New observations from the Hinode Stokes Polarimeter (SP) (with a spatial resolution of 0.3) reveal the ubiquitous presence of horizontal fields with an average value of about 55 G (Lites 2008). These observations show that, whereas the vertical magnetic field mainly occurs in the intergranular lanes at the network boundaries, the field in the internetwork regions is dominantly horizontal and well separated from the vertical fields.…”

Section: Internetwork Magnetic Fieldsmentioning

confidence: 99%

The Indian National Large Solar Telescope (NLST)

Hasan¹

2009

Proc. IAU

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Abstract. The Indian National Large Solar Telescope (NLST) will be a state-of-the-art 2-m class telescope for carrying out high resolution studies of the solar atmosphere. Sites in the Himalayan region at altitudes greater than 4000-m that have extremely low water vapor content and are unaffected by monsoons are under evaluation. This project is led by the Indian Institute of Astrophysics and has national and international partners.NLST is an on-axis alt-azimuth Gregorian multi-purpose open telescope with the provision of carrying out night time stellar observations using a spectrograph. The telescope utilizes an innovative design with low number of reflections to achieve a high throughput and low instrumental polarization. High order adaptive optics is integrated into the design that works with a modest Fried's parameter of 7-cm to give diffraction limited performance. The telescope will be equipped with a suite of post-focus instruments including a high resolution spectrograph and a polarimeter. A detailed concept design of the telescope is presently being finalized and fabrication is expected to begin in 2010 with first light in 2014.

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The Horizontal Magnetic Flux of the Quiet‐Sun Internetwork as Observed with theHinodeSpectro‐Polarimeter

Cited by 417 publications

References 38 publications

Is the Small-Scale Magnetic Field Correlated With the Dynamo Cycle?

Is the Small-Scale Magnetic Field Correlated With the Dynamo Cycle?

Magnetic Field and Convection in the Cool Supergiant Betelgeuse

The Indian National Large Solar Telescope (NLST)

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