Coronal Density Measurements Using Giant Radio Pulses of the Crab Pulsar at the Cycle 24/25 Minimum
Accurate measurements of the coronal plasma density profile, which varies with the solar cycle (SC), are necessary to elucidate the solar wind acceleration. In this study, the Crab pulsar is observed using the 327 MHz radio telescope at the Toyokawa Observatory of the Institute for Space-Earth Envir...
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ftnagoyauniv:oai:nagoya.repo.nii.ac.jp:02001978 2024-06-09T07:49:38+00:00 Coronal Density Measurements Using Giant Radio Pulses of the Crab Pulsar at the Cycle 24/25 Minimum Tokumaru, Munetoshi Maeda, Ryuya Tawara, Kaito Takefuji, Kazuhiro Terasawa, Toshio 2022-01-17 application/pdf https://nagoya.repo.nii.ac.jp/record/2001978/files/Tokumaru2022_Article_CoronalDensityMeasurementsUsin.pdf eng eng Springer https://doi.org/10.1007/s11207-021-01939-6 Solar Physics 1 297 10 0038-0938 https://nagoya.repo.nii.ac.jp/record/2001978/files/Tokumaru2022_Article_CoronalDensityMeasurementsUsin.pdf This article is licensed under a Creative Commons Attribution 4.0 International License 2022 ftnagoyauniv https://doi.org/10.1007/s11207-021-01939-6 2024-05-15T13:20:51Z Accurate measurements of the coronal plasma density profile, which varies with the solar cycle (SC), are necessary to elucidate the solar wind acceleration. In this study, the Crab pulsar is observed using the 327 MHz radio telescope at the Toyokawa Observatory of the Institute for Space-Earth Environmental Research of Nagoya University to investigate the coronal plasma density profile for radial distances between 5 and 60 solar radii at the SC24/25 minimum. We derive the dispersion measures (DMs) that represent the integration of plasma density along the line of sight (LOS) for giant radio pulses of the Crab pulsar. We find that the observed DMs increased above the interstellar background level when the LOS for the Crab pulsar approached the Sun in mid-June 2018 and 2019. This increase in DM is attributed to the effect of the coronal plasma. We determine the plasma density distribution by fitting a spherically symmetric model to the observed DM data. The flat radial slopes of the best-fit model are consistent with pulsar observations in the low-activity periods of past SCs, and they are attributed to the effect of the coronal hole over the south pole of the Sun. Our results show that the density level near the Sun is similar to those observed in the low activity periods of past SCs, implying recovery of the coronal plasma density from a significant reduction at the SC23/24 minimum. journal article Other/Unknown Material South pole Nagoya University: NAGOYA Repository South Pole Solar Physics 297 1 |
institution |
Open Polar |
collection |
Nagoya University: NAGOYA Repository |
op_collection_id |
ftnagoyauniv |
language |
English |
description |
Accurate measurements of the coronal plasma density profile, which varies with the solar cycle (SC), are necessary to elucidate the solar wind acceleration. In this study, the Crab pulsar is observed using the 327 MHz radio telescope at the Toyokawa Observatory of the Institute for Space-Earth Environmental Research of Nagoya University to investigate the coronal plasma density profile for radial distances between 5 and 60 solar radii at the SC24/25 minimum. We derive the dispersion measures (DMs) that represent the integration of plasma density along the line of sight (LOS) for giant radio pulses of the Crab pulsar. We find that the observed DMs increased above the interstellar background level when the LOS for the Crab pulsar approached the Sun in mid-June 2018 and 2019. This increase in DM is attributed to the effect of the coronal plasma. We determine the plasma density distribution by fitting a spherically symmetric model to the observed DM data. The flat radial slopes of the best-fit model are consistent with pulsar observations in the low-activity periods of past SCs, and they are attributed to the effect of the coronal hole over the south pole of the Sun. Our results show that the density level near the Sun is similar to those observed in the low activity periods of past SCs, implying recovery of the coronal plasma density from a significant reduction at the SC23/24 minimum. journal article |
author |
Tokumaru, Munetoshi Maeda, Ryuya Tawara, Kaito Takefuji, Kazuhiro Terasawa, Toshio |
spellingShingle |
Tokumaru, Munetoshi Maeda, Ryuya Tawara, Kaito Takefuji, Kazuhiro Terasawa, Toshio Coronal Density Measurements Using Giant Radio Pulses of the Crab Pulsar at the Cycle 24/25 Minimum |
author_facet |
Tokumaru, Munetoshi Maeda, Ryuya Tawara, Kaito Takefuji, Kazuhiro Terasawa, Toshio |
author_sort |
Tokumaru, Munetoshi |
title |
Coronal Density Measurements Using Giant Radio Pulses of the Crab Pulsar at the Cycle 24/25 Minimum |
title_short |
Coronal Density Measurements Using Giant Radio Pulses of the Crab Pulsar at the Cycle 24/25 Minimum |
title_full |
Coronal Density Measurements Using Giant Radio Pulses of the Crab Pulsar at the Cycle 24/25 Minimum |
title_fullStr |
Coronal Density Measurements Using Giant Radio Pulses of the Crab Pulsar at the Cycle 24/25 Minimum |
title_full_unstemmed |
Coronal Density Measurements Using Giant Radio Pulses of the Crab Pulsar at the Cycle 24/25 Minimum |
title_sort |
coronal density measurements using giant radio pulses of the crab pulsar at the cycle 24/25 minimum |
publisher |
Springer |
publishDate |
2022 |
url |
https://nagoya.repo.nii.ac.jp/record/2001978/files/Tokumaru2022_Article_CoronalDensityMeasurementsUsin.pdf |
geographic |
South Pole |
geographic_facet |
South Pole |
genre |
South pole |
genre_facet |
South pole |
op_relation |
https://doi.org/10.1007/s11207-021-01939-6 Solar Physics 1 297 10 0038-0938 https://nagoya.repo.nii.ac.jp/record/2001978/files/Tokumaru2022_Article_CoronalDensityMeasurementsUsin.pdf |
op_rights |
This article is licensed under a Creative Commons Attribution 4.0 International License |
op_doi |
https://doi.org/10.1007/s11207-021-01939-6 |
container_title |
Solar Physics |
container_volume |
297 |
container_issue |
1 |
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1801382348166529024 |