On the Combination of Imaging-Polarimetry With Spectropolarimetry of Upper Solar Atmospheres During Solar Eclipses

Qu, Zhongquan; Deng, Linhua; Dun, G. T.; Chang, Liang; Zhang, X. Y.; Cheng, Xiaojin; Allington‐Smith, J. R.; Murray, Graham J.; Xue, Zhike

doi:10.1088/0004-637x/774/1/71

Cited by 11 publications

(13 citation statements)

References 22 publications

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“…The peak polarization was 47% ± 1%, in the arms of the "Y" structure, at a distance of ∼ 1.5R . We do not measure any unexpectedly large polarization, of the kind discussed by Koutchmy & Schatten (1971) and reported more recently by Qu et al (2013). Deviations of the angle of polarization from the tangential direction have been reported by various groups, most recently by Skomorovsky et al (2012), Qu et al (2013), and Kim et al (2017).…”

Section: Polarization Of the Solar Coronasupporting

confidence: 71%

“…We do not measure any unexpectedly large polarization, of the kind discussed by Koutchmy & Schatten (1971) and reported more recently by Qu et al (2013). Deviations of the angle of polarization from the tangential direction have been reported by various groups, most recently by Skomorovsky et al (2012), Qu et al (2013), andKim et al (2017). We do not measure any deviations from the tangential direction, larger than 1 • .…”

Section: Polarization Of the Solar Coronasupporting

confidence: 51%

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Imaging Polarimetry of the 2017 Solar Eclipse with the RIT Polarization Imaging Camera

Vorobiev

Ninkov

Bernard

et al. 2020

PASP

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In the last decade, imaging polarimeters based on micropolarizer arrays have been developed for use in terrestrial remote sensing and metrology applications. Micropolarizer-based sensors are dramatically smaller and more mechanically robust than other polarimeters with similar spectral response and snapshot capability.To determine the suitability of these new polarimeters for astronomical applications, we developed the RIT Polarization Imaging Camera to investigate the performance of these devices, with a special attention to the low signal-to-noise regime. We characterized the device performance in the lab, by determining the relative throughput, efficiency, and orientation of every pixel, as a function of wavelength. Using the resulting pixel response model, we developed demodulation procedures for aperture photometry and imaging polarimetry observing modes. We found that, using the current calibration, RITPIC is capable of detecting polarization signals as small as ∼ 0.3%. To demonstrate the stability of RITPIC's calibration and its extreme portability, we performed imaging polarimetry of the Solar corona in Madras, Oregon during the total Solar eclipse of 2017. The maximum polarization we measured was ∼ 46%, which agrees well with the maximum value predicted for a Thomson scattering corona. Similarly, we found no strong deviations in the angle of linear polarization from the tangential direction. The relative ease of data collection, calibration, and analysis provided by these sensors suggest than they may become an important tool for a number of astronomical targets.Corresponding author: Dmitry Vorobiev 2 Vorobiev et al.

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Section: Polarization Of the Solar Coronasupporting

confidence: 71%

Section: Polarization Of the Solar Coronasupporting

confidence: 51%

Imaging Polarimetry of the 2017 Solar Eclipse with the RIT Polarization Imaging Camera

Vorobiev

Ninkov

Bernard

et al. 2020

PASP

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“…Unexpectedly large degrees of polarisation have been observed by a number of authors [Koutchmy and Schatten, 1971, Pepin, 1970, Skomorovsky et al, 2012, Qu et al, 2013. In these cases, the degree of polarisation exceeded the maximum non-relativistic Thomson scatter value expected for the observed elongation at a scattering angle χ = π/2.…”

Section: Discussion and Summarymentioning

confidence: 91%

Thomson Scattering in the Solar Corona

Inhester¹

2015

Preprint

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The basis for the application of Thomson scattering to the analysis of coronagraph images has been laid decades ago [Schuster, 1879, Minnaert, 1930, Van de Hulst, 1950. Even though the basic formulation is undebated, a discussion has grown in recent years about the spatial distribution of Thomson scatter sensitivity in the corona and the inner heliosphere. These notes are an attempt to clarify the understanding of this topic. We reformulate the classical scattering calculations in a more transparent way using modern SIcompatible quantities extended to field correlation matrices. The resulting concise formulation is easily extended to the case of relativistic electrons. For relativistic electrons we calculate the Stokes parameters of the scattered radiation and determine changes in degree and orientation of its polarisation, blue-shift and radiant intensities depending on the electron velocity magnitude and direction. We discuss the probability to see these relativistic effects in white-light coronagraph observations of the solar corona. Many mathematical and some basic physical ingredients are made explicit in several chapters of the appendix.

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“…The prototype FASOT (Qu et al, 2014) achieves real-time 2D spectro-imaging polarimetry of multiple lines by using a pair of integral field units (IFU, cf. Allington-Smith et al, 2002) constructed at Durham University CfAI and significantly reduces polarimetric noise levels by applying the polarimetric optical switching (POS) technique (Donati et al, 1990;Bianda, Solanki, and Stenflo, 1998).…”

Section: Instrumentation and Observationmentioning

confidence: 99%

“…The last category, spectro-imaging polarimetry, is presented here for the first time. This was performed during the 2013 total solar eclipse in Gabon with the prototype Fiber Ar- rayed Solar Optical Telescope (FASOT, Qu, 2011;Qu et al, 2014). Here the term 'spectroimaging polarimetry' means real-time 2D spectropolarimetry that enables the production of correspondingly reconstructed 2D polarization maps at all the wavelength points within the adopted band of interest.…”

Section: Introductionmentioning

confidence: 99%

Spectro-Imaging Polarimetry of the Local Corona During Solar Eclipse

Dun

Chang

et al. 2017

Sol Phys

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Results are presented from spectro-imaging polarimetry of radiation from the local solar corona during the 2013 total solar eclipse in Gabon. This polarimetric observation was performed from 516.3 nm to 532.6 nm using a prototype Fiber Arrayed Solar Optical Telescope (FASOT). A polarimetric noise level on the order of 10 −3 results from a reduced polarimetric optical switching demodulation (RPOSD) procedure for data reduction. It is revealed that the modality of fractional linear polarization profiles of the green coronal line shows a diversity, which may indicate complex mechanisms. The polarization degree can approach 3.2 % above the continuum polarization level on a scale of 1500 km, and the nonuniform spatial distribution in amplitude and polarization direction is found even within a small field of view of 7500 km. All of this implies that the coronal polarization is highly structured and complex even on a small scale.

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On the Combination of Imaging-Polarimetry With Spectropolarimetry of Upper Solar Atmospheres During Solar Eclipses

Cited by 11 publications

References 22 publications

Imaging Polarimetry of the 2017 Solar Eclipse with the RIT Polarization Imaging Camera

Imaging Polarimetry of the 2017 Solar Eclipse with the RIT Polarization Imaging Camera

Thomson Scattering in the Solar Corona

Spectro-Imaging Polarimetry of the Local Corona During Solar Eclipse

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