Quiet Sun Center to Limb Variation of the Linear Polarization Observed by CLASP2 Across the Mg ii 
               h and k Lines

Rachmeler, Laurel A.; Bueno, J. Trujillo; McKenzie, D. E.; Ishikawa, R.; Auchère, F.; Kobayashi, K.; Kano, Ryouhei; Okamoto, Takenori J.; Bethge, Christian; Song, Donguk; Ballester, Ernest Alsina; Belluzzi, L.; Alemán, T. del Pino; Yoshida, Masaki; Shimizu, Toshifumi; Winebarger, Amy R.; Kobelski, Adam; Vigil, Genevieve D.; Pontieu, Bart De; Suematsu, Y.; Narukage, Noriyuki; Kubo, Masahito; Sakao, Taro; Hara, Hirohisa; Štěpán, Jiří; Carlsson, Mats; Leenaarts, J.; Ramos, A. Asensio

doi:10.3847/1538-4357/ac83b8

Cited by 16 publications

(18 citation statements)

References 31 publications

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“…To this end, it is first important to identify the observational signature of the Hanle and MO effects in the CLASP2 data. In a recent paper we demonstrated that the Q/I and U/I patterns observed by CLASP2 across the Mg II h and k lines are indeed caused by the scattering of anisotropic radiation, with PRD and J-state interference playing a key role (Rachmeler et al 2022). In this paper, we aim at providing observational evidence of the operation of the Hanle effect in the core of the k line and of MO effects in the wings of the Mg II h and k lines.…”

Section: Introductionmentioning

confidence: 92%

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Evidence for the Operation of the Hanle and Magneto-optical Effects in the Scattering Polarization Signals Observed by CLASP2 across the Mg ii h and k Lines

Ishikawa

Bueno

Ballester

et al. 2023

ApJ

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Radiative transfer investigations of the solar Mg ii h and k resonance lines around 280 nm have shown that, while their circular polarization (Stokes V) signals arise from the Zeeman effect, the linear polarization profiles (Stokes Q and U) are dominated by the scattering of anisotropic radiation and the Hanle and magneto-optical (MO) effects. Using the unprecedented observations of the Mg ii and Mn i resonance lines obtained by the Chromospheric LAyer Spectro-Polarimeter (CLASP2), here we investigate how the linear polarization signals at different wavelengths (i.e., at the center, and at the near and far wings of the k line) vary with the longitudinal component of the magnetic field (B L ) at their approximate height of formation. The B L is estimated from the V signals in the aforementioned spectral lines. Particular attention is given to the following quantities that are expected to be influenced by the presence of magnetic fields through the Hanle and MO effects: the sign of the U signals, the total linear polarization amplitude (LP) and its direction (χ) with respect to a reference direction. We find that at the center and near wings of the k line, the behavior of these quantities is significantly different in the observed quiet and plage regions, and that both LP and χ seem to depend on B L . These observational results are indicative of the operation of the Hanle effect at the center of the k line and of the MO effects at the near wings of the k line.

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Section: Introductionmentioning

confidence: 92%

“…The distance from the disk center ranges from 546 8 to 740 9 (0.64 μ 0.82) and from 789 2 to 984 0 (μ 0.57) for the plage and limb targets, respectively. μ is the cosine of the heliocentric angle, which was determined by taking the limb location at 961 5 (Rachmeler et al 2022).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Evidence for the Operation of the Hanle and Magneto-optical Effects in the Scattering Polarization Signals Observed by CLASP2 across the Mg ii h and k Lines

Ishikawa

Bueno

Ballester

et al. 2023

ApJ

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“…In these cases, the full-width at half-maximum (FWHM) and equivalent width are often reported, or synthesized spectra with different abundance values are compared to the observations. Additionally, studies of the Lyman-α and Mg II h & k lines have been performed by Bonnet et al (1978) and Lemaire et al (1981), for example, and more recently by Gunár et al (2020Gunár et al ( , 2021, and Rachmeler et al (2022) to create quiet-Sun reference profiles which could serve as an incident radiation boundary condition for the radiative transfer modeling of chromospheric and coronal structures. Additionally, CLV measurements of the polarization of these lines have been studied by Rachmeler et al (2022), full disk integrated atlases were presented by Molaro & Monai (2012), and the formation height of several chromospheric lines was inferred by means of CLVs by Wittmann (1976).…”

Section: Introductionmentioning

confidence: 99%

Center-to-limb variation of spectral lines and continua observed with SST/CRISP and SST/CHROMIS

Pietrow

Kiselman

Andriienko

et al. 2023

A&A

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Context. Observations of center-to-limb variations (CLVs) of spectral lines and continua provide a good test for the accuracy of models with a solar and stellar atmospheric structure and spectral line formation. They are also widely used to constrain elemental abundances, and are becoming increasingly more important in atmospheric studies of exoplanets. However, only a few such data sets exist for chromospheric lines. Aims. We aim to create a set of standard profiles by means of mosaics made with the CRISP and CHROMIS instruments of the Swedish 1-m Solar Telescope (SST), as well as to explore the robustness of said profiles obtained using this method. Methods. For each spectral line, we used a mosaic that ranges from the center to the limb. Each of these mosaics were averaged down to 50 individual spectral profiles and spaced by 0.02 in the µ scale. These profiles were corrected for p-mode oscillations, and their line parameters (equivalent width, line shift, full-width at half-maximum, and line depth) were then compared against literature values whenever possible. Results. We present a set of 50 average profiles that are spaced equidistantly along the cosine of the heliocentric angle (µ) by steps of 0.02 for five continuum points between 4001 and 7772 Å, as well as ten of the most commonly observed spectral lines at the SST

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“…The results of theoretical spectropolarimetric investigations of ultraviolet (UV) chromospheric lines (see Trujillo , and references therein) led to the CLASP (Chromospheric Lyman Alpha SpectroPolarimeter; Kano et al 2012) and CLASP2 (Chromospheric LAyer Spectro-Polarimeter; Narukage et al 2016) suborbital rocket experiments. The former successfully measured the intensity and linear polarization in the hydrogen Lyα line in a quiet Sun region (Kano et al 2017), while the latter achieved full Stokes measurements in the UV region around the Mg II h and k resonance lines (between approximately 279.4 and 280.6 nm) in both a plage (Ishikawa et al 2021) and quiet Sun (Rachmeler et al 2022) regions.…”

Section: Introductionmentioning

confidence: 99%

The Circular Polarization of the Mn 1 Resonance Lines around 280 nm for Exploring Chromospheric Magnetism

Alemán

Ballester

Bueno

2022

ApJ

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We study the circular polarization of the Mn i resonance lines at 279.56, 279.91, and 280.19 nm (hereafter, UV multiplet) by means of radiative transfer modeling. In 2019, the CLASP2 mission obtained unprecedented spectropolarimetric data in a region of the solar ultraviolet including the Mg ii h and k resonance lines and two lines of a subordinate triplet, as well as two Mn i resonance lines. The first analysis of such data, in particular those corresponding to a plage region, allowed the inference of the longitudinal magnetic field from the photosphere to the upper chromosphere just below the transition region. This was achieved by applying the weak field approximation to the circular polarization profiles of the Mg ii and Mn i lines. While the applicability of this approximation to the Mg ii lines was already demonstrated in previous works, this is not the case for the Mn i UV multiplet. These lines are observed as absorptions between the Mg ii h and k lines, a region whose intensity is shaped by their partial frequency redistribution effects. Moreover, the only Mn i stable isotope has nuclear spin I = 5/2 and thus hyperfine structure must be, a priori, taken into account. Here we study the generation and transfer of the intensity and circular polarization of the Mn i resonance lines accounting for these physical ingredients. We analyze their sensitivity to the magnetic field by means of their response function, and we demonstrate the applicability of the weak field approximation to determine the longitudinal component of the magnetic field.

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Quiet Sun Center to Limb Variation of the Linear Polarization Observed by CLASP2 Across the Mg ii h and k Lines

Cited by 16 publications

References 31 publications

Evidence for the Operation of the Hanle and Magneto-optical Effects in the Scattering Polarization Signals Observed by CLASP2 across the Mg ii h and k Lines

Evidence for the Operation of the Hanle and Magneto-optical Effects in the Scattering Polarization Signals Observed by CLASP2 across the Mg ii h and k Lines

Center-to-limb variation of spectral lines and continua observed with SST/CRISP and SST/CHROMIS

The Circular Polarization of the Mn 1 Resonance Lines around 280 nm for Exploring Chromospheric Magnetism

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