The Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal T e with a Radiative Differential Emission Measure Inversion
Differential emission measure (DEM) inversion methods use the brightness of a set of emission lines to infer the line-of-sight (LOS) distribution of the electron temperature ( T _e ) in the corona. DEM inversions have been traditionally performed with collisionally excited lines at wavelengths in th...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acd10b |
| _version_ | 1827826250224238592 |
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| author | Benjamin Boe Cooper Downs Shadia Habbal |
| author_facet | Benjamin Boe Cooper Downs Shadia Habbal |
| author_sort | Benjamin Boe |
| collection | DOAJ |
| description | Differential emission measure (DEM) inversion methods use the brightness of a set of emission lines to infer the line-of-sight (LOS) distribution of the electron temperature ( T _e ) in the corona. DEM inversions have been traditionally performed with collisionally excited lines at wavelengths in the extreme ultraviolet and X-ray. However, such emission is difficult to observe beyond the inner corona (1.5 R _⊙ ), particularly in coronal holes. Given the importance of the T _e distribution in the corona for exploring the viability of different heating processes, we introduce an analog of the DEM specifically for radiatively excited coronal emission lines, such as those observed during total solar eclipses (TSEs) and with coronagraphs. This radiative-DEM (R-DEM) inversion utilizes visible and infrared emission lines that are excited by photospheric radiation out to at least 3 R _⊙ . Specifically, we use the Fe x (637 nm), Fe xi (789 nm), and Fe xiv (530 nm) coronal emission lines observed during the 2019 July 2 TSE near solar minimum. We find that, despite a large T _e spread in the inner corona, the distribution converges to an almost isothermal yet bimodal distribution beyond 1.4 R _⊙ , with T _e ranging from 1.1 to 1.4 in coronal holes and from 1.4 to 1.65 MK in quiescent streamers. Application of the R-DEM inversion to the Predictive Science Inc. magnetohydrodynamic simulation for the 2019 eclipse validates the R-DEM method and yields a similar LOS T _e distribution to the eclipse data. |
| first_indexed | 2024-03-12T03:03:16Z |
| format | Article |
| id | doaj.art-7a451218ed424f8c9f195f8bff6564a2 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:03:16Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-7a451218ed424f8c9f195f8bff6564a22023-09-03T14:36:25ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195115510.3847/1538-4357/acd10bThe Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal T e with a Radiative Differential Emission Measure InversionBenjamin Boe0https://orcid.org/0000-0002-6396-8209Cooper Downs1https://orcid.org/0000-0003-1759-4354Shadia Habbal2https://orcid.org/0000-0003-4089-9316Institute for Astronomy, University of Hawaii , Honolulu, HI 96822, USA ; bboe@hawaii.eduPredictive Science Inc. , San Diego, CA 92121, USAInstitute for Astronomy, University of Hawaii , Honolulu, HI 96822, USA ; bboe@hawaii.eduDifferential emission measure (DEM) inversion methods use the brightness of a set of emission lines to infer the line-of-sight (LOS) distribution of the electron temperature ( T _e ) in the corona. DEM inversions have been traditionally performed with collisionally excited lines at wavelengths in the extreme ultraviolet and X-ray. However, such emission is difficult to observe beyond the inner corona (1.5 R _⊙ ), particularly in coronal holes. Given the importance of the T _e distribution in the corona for exploring the viability of different heating processes, we introduce an analog of the DEM specifically for radiatively excited coronal emission lines, such as those observed during total solar eclipses (TSEs) and with coronagraphs. This radiative-DEM (R-DEM) inversion utilizes visible and infrared emission lines that are excited by photospheric radiation out to at least 3 R _⊙ . Specifically, we use the Fe x (637 nm), Fe xi (789 nm), and Fe xiv (530 nm) coronal emission lines observed during the 2019 July 2 TSE near solar minimum. We find that, despite a large T _e spread in the inner corona, the distribution converges to an almost isothermal yet bimodal distribution beyond 1.4 R _⊙ , with T _e ranging from 1.1 to 1.4 in coronal holes and from 1.4 to 1.65 MK in quiescent streamers. Application of the R-DEM inversion to the Predictive Science Inc. magnetohydrodynamic simulation for the 2019 eclipse validates the R-DEM method and yields a similar LOS T _e distribution to the eclipse data.https://doi.org/10.3847/1538-4357/acd10bSolar coronaSolar eclipsesSolar coronal streamersSolar coronal holesSolar optical telescopes |
| spellingShingle | Benjamin Boe Cooper Downs Shadia Habbal The Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal T e with a Radiative Differential Emission Measure Inversion The Astrophysical Journal Solar corona Solar eclipses Solar coronal streamers Solar coronal holes Solar optical telescopes |
| title | The Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal T e with a Radiative Differential Emission Measure Inversion |
| title_full | The Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal T e with a Radiative Differential Emission Measure Inversion |
| title_fullStr | The Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal T e with a Radiative Differential Emission Measure Inversion |
| title_full_unstemmed | The Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal T e with a Radiative Differential Emission Measure Inversion |
| title_short | The Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal T e with a Radiative Differential Emission Measure Inversion |
| title_sort | solar minimum eclipse of 2019 july 2 iii inferring the coronal t e with a radiative differential emission measure inversion |
| topic | Solar corona Solar eclipses Solar coronal streamers Solar coronal holes Solar optical telescopes |
| url | https://doi.org/10.3847/1538-4357/acd10b |
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