The Magnetic Landscape of the Sun's Polar Region

By S. Tsuneta, K. Ichimoto, Y. Katsukawa, B. Lites, K. Matsuzaki, S. Nagata, D. Súarez, T. Shimizu, M. Shimojo, R. Shine and 4 more. 2008

181 citations recorded by the source corpus.

We present observations of the magnetic landscape of the polar region of the Sun that are unprecedented in terms of spatial resolution, field of view, and polarimetric precision. They were carried out with the Solar Optical Telescope aboard Hinode. Using a Milne-Eddington inversion, we find many vertically oriented magnetic flux tubes with field strengths as strong as 1 kG scattered in latitude between 70° and 90°. They all have the same polarity, consistent with the global polarity of the polar region. The field vectors are observed to diverge from the centers of the flux elements, consistent with a view of magnetic fields that are expanding and fanning out with height. The polar region is also found to have ubiquitous horizontal fields. The polar regions are the source of the fast solar wind, which is channeled along unipolar coronal magnetic fields whose photospheric source is evidently rooted in the strong-field, vertical patches of flux. We conjecture that vertical flux tubes with large expansion around the photospheric-coronal boundary serve as efficient chimneys for Alfvén waves that accelerate the solar wind.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/019b66ae953986e70295d7ff713016da903c9414

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Citations in the corpus

• The Open Flux Problem (2017, background): “Tsuneta et al. (2008) estimated that the concentrated kilogauss patches that they observed would give the equivalent flux of a 10 G field over the region 20° from the pole; integrating the polar field from the NSO VSM synoptic map for that time period (2007 March 16, during CR2054) yields ∼6 G.”
• Solar Orbiter (2012, methodology): “The high resolution of Hinode’s Solar Optical Telescope (SOT) can partly overcome the second disadvantage (Tsuneta et al., 2008), but not the first.”
• Predicting the corona for the 21 August 2017 total solar eclipse (2018, methodology): “To make the polar field less smooth the flux was concentrated into small localized flux elements (Tsuneta et al. 2008), using ∼ 400 small flux patches in the north polar cap and ∼ 150 in the south polar cap, picked randomly in strength from a Gaussian distribution whose mean matched the fitted…”
• The Sun’s Supergranulation (2010, background): “Worden and Simon (1976) suggested a supergranulation lifetime of 36h.”
• Multiwavelength Studies of MHD Waves in the Solar Chromosphere (2015, methodology): “Our present fleet of telescopes able to observe the solar chromosphere includes the 0.5 m Solar Optical Telescope (SOT; Tsuneta et al. 2008a; Suematsu et al. 2008b) onboard the Hinode spacecraft (Kosugi et al. 2007), the 0.76 m Dunn Solar Telescope (DST; formerly the Vacuum Tower Telescope; Dunn…”