A Comparative Study of Two Contrasting Cosmic-Ray Events Caused by Solar Eruptions from NOAA AR 12673 in 2017 September
Two major solar eruptions on AR 12673 produced a Forbush decrease (FD) event (reduction of cosmic rays) on 2017 September 8 and ground-level enhancement (GLE; enhancement of cosmic rays) on 2017 September 10. The occurrence of two contrasting cosmic-ray events within 2 days that are associated with...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2023-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ad0550 |
| _version_ | 1797373924857610240 |
|---|---|
| author | Xiao Xia Yu Shuang Nan Zhang Hong Lu Hong Bo Hu Ping Zhang Wei Kang Gao |
| author_facet | Xiao Xia Yu Shuang Nan Zhang Hong Lu Hong Bo Hu Ping Zhang Wei Kang Gao |
| author_sort | Xiao Xia Yu |
| collection | DOAJ |
| description | Two major solar eruptions on AR 12673 produced a Forbush decrease (FD) event (reduction of cosmic rays) on 2017 September 8 and ground-level enhancement (GLE; enhancement of cosmic rays) on 2017 September 10. The occurrence of two contrasting cosmic-ray events within 2 days that are associated with two similar X-class solar flares (X9.3 and X8.2) and share the same active region on the Sun provides us a rare opportunity to understand the dominant factors in determining the properties of transient cosmic-ray events. Using a suite of modern-day instruments continuously tracking solar eruptions from the Sun to the Earth with ground-based cosmic-ray detectors, we reveal the complete cause–effect chain of activities for these two events. We conclude that the different consequences on the ground arise from two effects of the eruptions near the Sun: (1) the geometric effect of CMEs and (2) the intensity effect of CME-driven shocks. The first eruption, which originated at the heliographic longitude of W34° on 2017 September 6, had its CME ejecta and CME-driven shock intercept the Earth, leading to the FD event. The second eruption, which occurred on September 10 at W88°, only had its far flank reach the Earth. The peak shock speed of 3344 km s ^−1 of the second eruption, much faster than the 2175 km s ^−1 of the first eruption, is the dominant factor producing the GLE event, even though the first eruption is better connected magnetically to the Earth and has a similar flare. The results indicate that the production of GLE particles can be dominated by fast-enough CME-driven shocks. |
| first_indexed | 2024-03-08T18:57:28Z |
| format | Article |
| id | doaj.art-06a1bd4481414f08b2101f9c66533997 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-08T18:57:28Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-06a1bd4481414f08b2101f9c665339972023-12-28T10:10:05ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0196018510.3847/1538-4357/ad0550A Comparative Study of Two Contrasting Cosmic-Ray Events Caused by Solar Eruptions from NOAA AR 12673 in 2017 SeptemberXiao Xia Yu0https://orcid.org/0000-0002-5499-7817Shuang Nan Zhang1https://orcid.org/0000-0001-5586-1017Hong Lu2Hong Bo Hu3Ping Zhang4Wei Kang Gao5Key Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing, 100049, People’s Republic of China xxyu@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing, 100049, People’s Republic of China xxyu@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing, 100049, People’s Republic of China xxyu@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing, 100049, People’s Republic of China xxyu@ihep.ac.cnDepartment of Physics and Technology, Wuhan University , Wuhan, 430072, People’s Republic of China; WHU-NAOC Joint Center for Astronomy, Wuhan University , Wuhan, 430072, People’s Republic of ChinaKey Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing, 100049, People’s Republic of China xxyu@ihep.ac.cnTwo major solar eruptions on AR 12673 produced a Forbush decrease (FD) event (reduction of cosmic rays) on 2017 September 8 and ground-level enhancement (GLE; enhancement of cosmic rays) on 2017 September 10. The occurrence of two contrasting cosmic-ray events within 2 days that are associated with two similar X-class solar flares (X9.3 and X8.2) and share the same active region on the Sun provides us a rare opportunity to understand the dominant factors in determining the properties of transient cosmic-ray events. Using a suite of modern-day instruments continuously tracking solar eruptions from the Sun to the Earth with ground-based cosmic-ray detectors, we reveal the complete cause–effect chain of activities for these two events. We conclude that the different consequences on the ground arise from two effects of the eruptions near the Sun: (1) the geometric effect of CMEs and (2) the intensity effect of CME-driven shocks. The first eruption, which originated at the heliographic longitude of W34° on 2017 September 6, had its CME ejecta and CME-driven shock intercept the Earth, leading to the FD event. The second eruption, which occurred on September 10 at W88°, only had its far flank reach the Earth. The peak shock speed of 3344 km s ^−1 of the second eruption, much faster than the 2175 km s ^−1 of the first eruption, is the dominant factor producing the GLE event, even though the first eruption is better connected magnetically to the Earth and has a similar flare. The results indicate that the production of GLE particles can be dominated by fast-enough CME-driven shocks.https://doi.org/10.3847/1538-4357/ad0550Solar coronal mass ejections |
| spellingShingle | Xiao Xia Yu Shuang Nan Zhang Hong Lu Hong Bo Hu Ping Zhang Wei Kang Gao A Comparative Study of Two Contrasting Cosmic-Ray Events Caused by Solar Eruptions from NOAA AR 12673 in 2017 September The Astrophysical Journal Solar coronal mass ejections |
| title | A Comparative Study of Two Contrasting Cosmic-Ray Events Caused by Solar Eruptions from NOAA AR 12673 in 2017 September |
| title_full | A Comparative Study of Two Contrasting Cosmic-Ray Events Caused by Solar Eruptions from NOAA AR 12673 in 2017 September |
| title_fullStr | A Comparative Study of Two Contrasting Cosmic-Ray Events Caused by Solar Eruptions from NOAA AR 12673 in 2017 September |
| title_full_unstemmed | A Comparative Study of Two Contrasting Cosmic-Ray Events Caused by Solar Eruptions from NOAA AR 12673 in 2017 September |
| title_short | A Comparative Study of Two Contrasting Cosmic-Ray Events Caused by Solar Eruptions from NOAA AR 12673 in 2017 September |
| title_sort | comparative study of two contrasting cosmic ray events caused by solar eruptions from noaa ar 12673 in 2017 september |
| topic | Solar coronal mass ejections |
| url | https://doi.org/10.3847/1538-4357/ad0550 |
| work_keys_str_mv | AT xiaoxiayu acomparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT shuangnanzhang acomparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT honglu acomparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT hongbohu acomparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT pingzhang acomparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT weikanggao acomparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT xiaoxiayu comparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT shuangnanzhang comparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT honglu comparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT hongbohu comparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT pingzhang comparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september AT weikanggao comparativestudyoftwocontrastingcosmicrayeventscausedbysolareruptionsfromnoaaar12673in2017september |