Structure and Dynamics of the 2012 November 13/14 Eclipse White-Light Corona

Pasachoff, Jay M.; Rusin, V.; Санига, Метод; Babcock, B. A.; Lu, M.; Davis, Allen B.; Dantowitz, Ron; Gaintatzis, P.; Seiradakis, J. H.; Voulgaris, Aris; Seaton, Daniel B.; Shiota, Kazuo

doi:10.1088/0004-637x/800/2/90

Cited by 23 publications

(7 citation statements)

References 55 publications

(84 reference statements)

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“…At small radius, the flattening index cannot be calculated because of saturated pixels. However, the produced flattening profile and determined Ludendorff index are in agreement with the result of Pasachoff et al (2015) who obtained a + b = 0.01. Visual inspection may lead to an approximated value of R max = 1.3 R ⊙ since ǫ reaches its maximum at this radius.…”

Section: Flattening Profilesupporting

confidence: 91%

Shape parameters of the solar corona from 1991 to 2016

Priyatikanto

2016

Res. Astron. Astrophys.

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The global structure of the solar corona observed in the optical window is governed by the global magnetic field with different characteristics over a solar activity cycle. The Ludendorff flattening index has become a popular measure of global structure of the solar corona as observed during an eclipse. In this study, 15 digital images of the solar corona from 1991 to 2016 were analyzed in order to construct coronal flattening profiles as a function of radius. In most cases, the profile can be modeled with a 2nd order polynomial function so that the radius with maximum flattening index (Rmax) can be determined. Along with this value, Ludendorff index (a + b) was also calculated. Both Ludendorff index and Rmax show anti-correlation with monthly sunspot number, though the Rmax values are more scattered. The variation in Rmax can be regarded as the impact of the changing coronal brightness profile over the equator.

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Section: Flattening Profilesupporting

confidence: 91%

Shape parameters of the solar corona from 1991 to 2016

Priyatikanto

2016

Res. Astron. Astrophys.

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“…At small radius, flattening index can not be calculated because of saturated pixels. However, the produced flattening profile and determined Ludendorff index is in agreement with the result of Pasachoff et al (2015) who obtained a + b = 0.01. Visual inspection may lead to approximated value of R max = 1.3 R ⊙ since ǫ reach maximum at this radius.…”

Section: Flattening Profilesupporting

confidence: 91%

Shape Parameters of 1991 to 2016 Solar Corona

Priyatikanto

2016

Preprint

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The global structure of solar corona observed in optical window is governed by the global magnetic field with different characteristics over solar activity cycle. Ludendorff flattening index becomes a popular measure of the global structure of solar corona as observed during eclipse. In this study, 15 digital images of solar corona from 1991 to 2016 were analyzed in order to construct the coronal flattening profiles as a function of radius. In most of the cases, the profile can be modeled with 2nd order polynomial function so that the radius with maximum flattening index (R max ) can be determined. Along with this value, Ludendorff index (a + b) was also calculated. Both Ludendorff index and R max show anti-correlation with monthly sunspot number, though the R max values are more scattered. The variation of R max can be regarded as the impact of changing coronal brightness profile over equator.

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“…In the solar maximum, the number of active regions increases, which makes the magnetic field structure complex. Changes in coronal structure are well captured observationally by coronagraphs (Koutchmy & Livshits 1992;Decraemer et al 2019) and during the solar eclipses (Pasachoff et al 2015;Mikić et al 2018). They are also predicted using coronal field modeling (Yeates 2014).…”

Section: Introductionmentioning

confidence: 64%

Which Component of Solar Magnetic Field Drives the Evolution of Interplanetary Magnetic Field over the Solar Cycle?

Yoshida

Shimizu

Toriumi

2023

ApJ

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The solar magnetic structure changes over the solar cycle. It has a dipole structure during solar minimum, where the open flux extends mainly from the polar regions into the interplanetary space. During maximum, a complex structure is formed with low-latitude active regions and weakened polar fields, resulting in spread open field regions. However, the components of the solar magnetic field that are responsible for long-term variations in the interplanetary magnetic field (IMF) are not clear, and the IMF strength estimated based on the solar magnetic field is known to be underestimated by a factor of 3–4 against the actual in situ observations (the open flux problem). To this end, we decomposed the coronal magnetic field into the components of the spherical harmonic function of degree and order (ℓ, m) using the potential field source surface model with synoptic maps from SDO/HMI for 2010–2021. As a result, we found that the IMF rapidly increased in 2014 December (7 months after the solar maximum), which coincided with the increase in the equatorial dipole, (ℓ, m) = (1, ±1), corresponding to the diffusion of active regions toward the poles and in the longitudinal direction. The IMF gradually decreased until 2019 December (solar minimum) and its variation corresponded to that of the nondipole component ℓ ≥ 2. Our results suggest that the understanding of the open flux problem may be improved by focusing on the equatorial dipole and the nondipole component and that the influence of the polar magnetic field is less significant.

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Structure and Dynamics of the 2012 November 13/14 Eclipse White-Light Corona

Cited by 23 publications

References 55 publications

Shape parameters of the solar corona from 1991 to 2016

Shape parameters of the solar corona from 1991 to 2016

Shape Parameters of 1991 to 2016 Solar Corona

Which Component of Solar Magnetic Field Drives the Evolution of Interplanetary Magnetic Field over the Solar Cycle?

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