Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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MULTILAYER SPECTRAL INVERSION OF SOLAR Hα AND CA II 8542 LINE SPECTRA WITH HEIGHT-VARYING ABSORPTION PROFILES

  • Chae, Jongchul (Astronomy Program, Department of Physics and Astronomy, Seoul National University) ;
  • Cho, Kyuhyoun (Astronomy Program, Department of Physics and Astronomy, Seoul National University) ;
  • Kang, Juhyung (Astronomy Program, Department of Physics and Astronomy, Seoul National University) ;
  • Lee, Kyoung-Sun (Astronomy Program, Department of Physics and Astronomy, Seoul National University) ;
  • Kwak, Hannah (Astronomy Program, Department of Physics and Astronomy, Seoul National University) ;
  • Lim, Eun-Kyung (Solar and Space Weather Group, Korea Astronomy and Space Science Institute)
  • Received : 2021.08.09
  • Accepted : 2021.09.14
  • Published : 2021.10.31
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Abstract

We present an updated version of the multilayer spectral inversion (MLSI) recently proposed as a technique to infer the physical parameters of plasmas in the solar chromosphere from a strong absorption line. In the original MLSI, the absorption profile was constant over each layer of the chromosphere, whereas the source function was allowed to vary with optical depth. In our updated MLSI, the absorption profile is allowed to vary with optical depth in each layer and kept continuous at the interface of two adjacent layers. We also propose a new set of physical requirements for the parameters useful in the constrained model fitting. We apply this updated MLSI to two sets of Hα and Ca II line spectral data taken by the Fast Imaging Solar Spectrograph (FISS) from a quiet region and an active region, respectively. We find that the new version of the MLSI satisfactorily fits most of the observed line profiles of various features, including a network feature, an internetwork feature, a mottle feature in a quiet region, and a plage feature, a superpenumbral fibril, an umbral feature, and a fast downflow feature in an active region. The MLSI can also yield physically reasonable estimates of hydrogen temperature and nonthermal speed as well as Doppler velocities at different atmospheric levels. We conclude that the MLSI is a very useful tool to analyze the Hα line and the Ca II 8542 line spectral daya, and will promote the investigation of physical processes occurring in the solar photosphere and chromosphere.

Keywords

Acknowledgement

This research was supported by the National Research Foundation of the Korea (NRF) via grant no. NRF-2020R1A2C2004616. K.C. was also supported by the Basic Science Research Program through the NRF funded by the Ministry of Education (NRF-2020R1I1A1A01068789). K.-S.L. was also supported by an NRF grant funded by the Korean Ministry of Science and ICT (NRF-2021R1A2C1010881). E.-K.L. acknowledges support from basic research funding from the Korea Astronomy and Space Science Institute (KASI).

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