Investigating the IBEX Ribbon Structure a Solar Cycle Apart
A “Ribbon” of enhanced energetic neutral atom (ENA) emissions was discovered by the Interstellar Boundary Explorer in 2009, redefining our understanding of the heliosphere boundaries and the physical processes occurring at the interstellar interface. The Ribbon signal is intertwined with that of a g...
| 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/acda8b |
| _version_ | 1797694583679746048 |
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| author | M. A. Dayeh E. J. Zirnstein P. Swaczyna D. J. McComas |
| author_facet | M. A. Dayeh E. J. Zirnstein P. Swaczyna D. J. McComas |
| author_sort | M. A. Dayeh |
| collection | DOAJ |
| description | A “Ribbon” of enhanced energetic neutral atom (ENA) emissions was discovered by the Interstellar Boundary Explorer in 2009, redefining our understanding of the heliosphere boundaries and the physical processes occurring at the interstellar interface. The Ribbon signal is intertwined with that of a globally distributed flux (GDF) that spans the entire sky. To a certain extent, Ribbon separation methods enabled examining its evolution independent of the underlying GDF. Observations over a full solar cycle revealed the Ribbon’s evolving nature, with intensity variations closely tracking those of the solar wind (SW) structure after a few years delay, accounting for the SW–ENA recycling process. In this work, we examine the Ribbon structure, namely its ENA fluxes, angular extent, width, and circularity properties for two years, 2009 and 2019, representative of the declining phases of two adjacent solar cycles. We find that, (i) the Ribbon ENA fluxes have recovered in the nose direction and south of it down to ∼25° (for energies below 1.7 keV) and not at mid and high ecliptic latitudes; (ii) the Ribbon width exhibits significant variability as a function of azimuthal angle; (iii) circularity analysis suggests that the 2019 Ribbon exhibits a statistically consistent radius with that in 2009. The Ribbon’s partial recovery is aligned with the consensus of a heliosphere with its closest point being southward of the nose region. The large variability of the Ribbon width as a function of azimuth in 2019 compared to 2009 is likely indicative of small-scale processes within the Ribbon. |
| first_indexed | 2024-03-12T02:58:58Z |
| format | Article |
| id | doaj.art-498dd74765c64ddeac7bf0c6c83dacb8 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T02:58:58Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-498dd74765c64ddeac7bf0c6c83dacb82023-09-03T14:54:06ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195211910.3847/1538-4357/acda8bInvestigating the IBEX Ribbon Structure a Solar Cycle ApartM. A. Dayeh0https://orcid.org/0000-0001-9323-1200E. J. Zirnstein1https://orcid.org/0000-0001-7240-0618P. Swaczyna2https://orcid.org/0000-0002-9033-0809D. J. McComas3https://orcid.org/0000-0001-6160-1158Southwest Research Institute , San Antonio, TX 78238, USA ; maldayeh@swri.edu; University of Texas at San Antonio , San Antonio, TX 78249, USADepartment of Astrophysical Sciences, Princeton University , Princeton, NJ 08544, USADepartment of Astrophysical Sciences, Princeton University , Princeton, NJ 08544, USADepartment of Astrophysical Sciences, Princeton University , Princeton, NJ 08544, USAA “Ribbon” of enhanced energetic neutral atom (ENA) emissions was discovered by the Interstellar Boundary Explorer in 2009, redefining our understanding of the heliosphere boundaries and the physical processes occurring at the interstellar interface. The Ribbon signal is intertwined with that of a globally distributed flux (GDF) that spans the entire sky. To a certain extent, Ribbon separation methods enabled examining its evolution independent of the underlying GDF. Observations over a full solar cycle revealed the Ribbon’s evolving nature, with intensity variations closely tracking those of the solar wind (SW) structure after a few years delay, accounting for the SW–ENA recycling process. In this work, we examine the Ribbon structure, namely its ENA fluxes, angular extent, width, and circularity properties for two years, 2009 and 2019, representative of the declining phases of two adjacent solar cycles. We find that, (i) the Ribbon ENA fluxes have recovered in the nose direction and south of it down to ∼25° (for energies below 1.7 keV) and not at mid and high ecliptic latitudes; (ii) the Ribbon width exhibits significant variability as a function of azimuthal angle; (iii) circularity analysis suggests that the 2019 Ribbon exhibits a statistically consistent radius with that in 2009. The Ribbon’s partial recovery is aligned with the consensus of a heliosphere with its closest point being southward of the nose region. The large variability of the Ribbon width as a function of azimuth in 2019 compared to 2009 is likely indicative of small-scale processes within the Ribbon.https://doi.org/10.3847/1538-4357/acda8bHeliosphereSolar windPickup ionsHeliosheathInterstellar magnetic fieldsSolar cycle |
| spellingShingle | M. A. Dayeh E. J. Zirnstein P. Swaczyna D. J. McComas Investigating the IBEX Ribbon Structure a Solar Cycle Apart The Astrophysical Journal Heliosphere Solar wind Pickup ions Heliosheath Interstellar magnetic fields Solar cycle |
| title | Investigating the IBEX Ribbon Structure a Solar Cycle Apart |
| title_full | Investigating the IBEX Ribbon Structure a Solar Cycle Apart |
| title_fullStr | Investigating the IBEX Ribbon Structure a Solar Cycle Apart |
| title_full_unstemmed | Investigating the IBEX Ribbon Structure a Solar Cycle Apart |
| title_short | Investigating the IBEX Ribbon Structure a Solar Cycle Apart |
| title_sort | investigating the ibex ribbon structure a solar cycle apart |
| topic | Heliosphere Solar wind Pickup ions Heliosheath Interstellar magnetic fields Solar cycle |
| url | https://doi.org/10.3847/1538-4357/acda8b |
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