The article “Quiet Sun Center to Limb Variation of the Linear Polarization Observed by CLASP2 Across the Mg II h and k Lines”, by Laurel Rachmeler (NOAA) has been accepted for publication in The Astrophysical Journal. The CLASP2 (Chromospheric LAyer Spectro-Polarimeter 2) sounding rocket mission measured the four Stokes parameters of the Mg II h and k spectral region around 2800 Å along a 200″ slit at three locations on the solar disk, achieving the first spatially and spectrally resolved observations of the solar polarization in this near-ultraviolet region. The focus of the article is the center-to-limb variation of the linear polarization across these resonance lines, which is produced by the scattering of anisotropic radiation in the solar atmosphere and is sensitive to the magnetic field from the low to the upper chromosphere through the Hanle and magneto-optical effects. MSFC co-authors are David McKenzie, Ken Kobayashi, Amy Winebarger, Adam Kobelski, and Genevieve Vigil (ST13).
Read the article at: https://iopscience.iop.org/article/10.3847/1538-4357/ac83b8/meta.
Center-to-limb variation of the far wings of Mg ii h and k in Q/I and U/I as a function of arcseconds from the disk center and solar μ, with the colored dots showing the CLASP2 data and the solid curves the theoretical Q/I signals calculated in the unmagnetized FAL-C semiempirical model. Note that U/I = 0 in any static one-dimensional unmagnetized model like FAL-C. Dashed lines indicate the location of the limb and zero-polarization. The colors of the dots correspond to the shaded wavelength ranges in Figure 3. The reference direction for positive Stokes Q is parallel to the nearest limb. The 3σ photon noise error on on the dots is roughly 0.14% on-disk and 0.6% off-limb.