Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images
Understanding the solar corona requires knowledge of its dynamics through its various layers and subsequent connectivity to the heliosphere. This requires understanding the nature of the outflows and the physical transitions through the middle corona (∼1.5–6.0 R _s ). While this region is still inac...
| 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 |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/acba08 |
| _version_ | 1827826828273778688 |
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| author | Nathalia Alzate Huw Morgan Simone Di Matteo |
| author_facet | Nathalia Alzate Huw Morgan Simone Di Matteo |
| author_sort | Nathalia Alzate |
| collection | DOAJ |
| description | Understanding the solar corona requires knowledge of its dynamics through its various layers and subsequent connectivity to the heliosphere. This requires understanding the nature of the outflows and the physical transitions through the middle corona (∼1.5–6.0 R _s ). While this region is still inaccessible to in situ measurements, remote sensing observations are available, but their interpretation can be controversial due to line-of-sight effects and the nonradial motion of outflowing structures close to the Sun (≤3.0 R _s ). In this work, we describe a method to mitigate these challenges by generating nonradial height–time profiles of outflows by using advanced image processing techniques. The northern and southern boundaries of a large equatorial streamer during the 2008 solar minimum were identified in STEREO/SECCHI solar images, using two different methodologies based on thresholds of brightness and piecewise polynomial function fitting. To address line-of-sight issues, we used tomographic reconstruction of the 3D distribution of the coronal electron density based on SECCHI/COR2 images. Spectral analysis of the time series of the position angle of the streamer boundary revealed its oscillatory nature at some heights at 36–48 and 10.5–14.6 hr. Dividing the distance between the northern and southern streamer boundaries in equal parts at each height, we obtained nonradial height–time paths from which we generated nonradial profiles of corona/solar wind plasma outflow. We tracked outflows as they moved uninterruptedly from the Sun in EUVI, through COR1 and into COR2. Finally, we discuss the preliminary results of nonradial plane-of-sky velocities for a coronal mass ejection and two small-scale features. |
| first_indexed | 2024-03-12T03:16:54Z |
| format | Article |
| id | doaj.art-5c628dfced654d74acdb3f12a6866a87 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:16:54Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-5c628dfced654d74acdb3f12a6866a872023-09-03T14:08:23ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01945211610.3847/1538-4357/acba08Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar ImagesNathalia Alzate0https://orcid.org/0000-0001-5207-9628Huw Morgan1https://orcid.org/0000-0002-6547-5838Simone Di Matteo2https://orcid.org/0000-0001-6407-7574NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA ; nathalia.alzate@nasa.gov; ADNET Systems Inc. , Greenbelt, MD 20771, USAAberystwyth University Ceredigion , Cymru SY23 3BZ, UKNASA Goddard Space Flight Center , Greenbelt, MD 20771, USA ; nathalia.alzate@nasa.gov; The Catholic University of America , Washington, DC, USAUnderstanding the solar corona requires knowledge of its dynamics through its various layers and subsequent connectivity to the heliosphere. This requires understanding the nature of the outflows and the physical transitions through the middle corona (∼1.5–6.0 R _s ). While this region is still inaccessible to in situ measurements, remote sensing observations are available, but their interpretation can be controversial due to line-of-sight effects and the nonradial motion of outflowing structures close to the Sun (≤3.0 R _s ). In this work, we describe a method to mitigate these challenges by generating nonradial height–time profiles of outflows by using advanced image processing techniques. The northern and southern boundaries of a large equatorial streamer during the 2008 solar minimum were identified in STEREO/SECCHI solar images, using two different methodologies based on thresholds of brightness and piecewise polynomial function fitting. To address line-of-sight issues, we used tomographic reconstruction of the 3D distribution of the coronal electron density based on SECCHI/COR2 images. Spectral analysis of the time series of the position angle of the streamer boundary revealed its oscillatory nature at some heights at 36–48 and 10.5–14.6 hr. Dividing the distance between the northern and southern streamer boundaries in equal parts at each height, we obtained nonradial height–time paths from which we generated nonradial profiles of corona/solar wind plasma outflow. We tracked outflows as they moved uninterruptedly from the Sun in EUVI, through COR1 and into COR2. Finally, we discuss the preliminary results of nonradial plane-of-sky velocities for a coronal mass ejection and two small-scale features.https://doi.org/10.3847/1538-4357/acba08Solar coronaSolar windAstronomical techniquesQuiet sun |
| spellingShingle | Nathalia Alzate Huw Morgan Simone Di Matteo Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images The Astrophysical Journal Solar corona Solar wind Astronomical techniques Quiet sun |
| title | Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images |
| title_full | Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images |
| title_fullStr | Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images |
| title_full_unstemmed | Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images |
| title_short | Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images |
| title_sort | tracking nonradial outflows in extreme ultraviolet and white light solar images |
| topic | Solar corona Solar wind Astronomical techniques Quiet sun |
| url | https://doi.org/10.3847/1538-4357/acba08 |
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