Velocity and Density Fluctuations in the Quiet Sun Corona
We investigate the properties and relationship between Doppler velocity fluctuations and intensity fluctuations in the off-limb quiet Sun corona. These are expected to reflect the properties of Alfvénic and compressive waves, respectively. The data come from the Coronal Multichannel Polarimeter (COM...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/adc1c0 |
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| author | Michael Hahn Xiangrong Fu Stefan J. Hofmeister Yifan Huang Alexandros Koukras Daniel Wolf Savin |
| author_facet | Michael Hahn Xiangrong Fu Stefan J. Hofmeister Yifan Huang Alexandros Koukras Daniel Wolf Savin |
| author_sort | Michael Hahn |
| collection | DOAJ |
| description | We investigate the properties and relationship between Doppler velocity fluctuations and intensity fluctuations in the off-limb quiet Sun corona. These are expected to reflect the properties of Alfvénic and compressive waves, respectively. The data come from the Coronal Multichannel Polarimeter (COMP). These data were studied using spectral methods to estimate the power spectra, amplitudes, perpendicular correlation lengths, phases, trajectories, dispersion relations, and propagation speeds of both types of fluctuations. We find that most velocity fluctuations are due to Alfvénic waves but that intensity fluctuations come from a variety of sources, likely including fast and slow mode waves, as well as aperiodic variations. The relation between the velocity and intensity fluctuations differs depending on the underlying coronal structure. On short closed loops, the velocity and intensity fluctuations have similar power spectra and speeds. In contrast, on longer nearly radial trajectories, the velocity and intensity fluctuations have different power spectra, with the velocity fluctuations propagating at much faster speeds than the intensity fluctuations. Considering the temperature sensitivity of COMP, these longer structures are more likely to be closed fields lines of the quiet Sun rather than cooler open field lines. That is, we find the character of the interactions of Alfvénic waves and density fluctuations depends on the length of the magnetic loop on which they are traveling. |
| format | Article |
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| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-844d6b0ab569453eb5d28bbf49ed68f72025-08-20T03:53:42ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198416910.3847/1538-4357/adc1c0Velocity and Density Fluctuations in the Quiet Sun CoronaMichael Hahn0https://orcid.org/0000-0001-7748-4179Xiangrong Fu1Stefan J. Hofmeister2https://orcid.org/0000-0001-7662-1960Yifan Huang3https://orcid.org/0000-0002-0422-2925Alexandros Koukras4https://orcid.org/0000-0002-6232-5527Daniel Wolf Savin5https://orcid.org/0000-0002-1111-6610Columbia Astrophysics Laboratory, Columbia University , 550 West 120th Street, New York, NY 10027, USA ; mhahn@astro.columbia.eduLos Alamos National Laboratory , P.O. Box 1663, Los Alamos, NM 87545, USA; New Mexico Consortium , 4200 W Jemez Rd #200, Los Alamos, NM 87544, USAColumbia Astrophysics Laboratory, Columbia University , 550 West 120th Street, New York, NY 10027, USA ; mhahn@astro.columbia.eduLos Alamos National Laboratory , P.O. Box 1663, Los Alamos, NM 87545, USAColumbia Astrophysics Laboratory, Columbia University , 550 West 120th Street, New York, NY 10027, USA ; mhahn@astro.columbia.eduColumbia Astrophysics Laboratory, Columbia University , 550 West 120th Street, New York, NY 10027, USA ; mhahn@astro.columbia.eduWe investigate the properties and relationship between Doppler velocity fluctuations and intensity fluctuations in the off-limb quiet Sun corona. These are expected to reflect the properties of Alfvénic and compressive waves, respectively. The data come from the Coronal Multichannel Polarimeter (COMP). These data were studied using spectral methods to estimate the power spectra, amplitudes, perpendicular correlation lengths, phases, trajectories, dispersion relations, and propagation speeds of both types of fluctuations. We find that most velocity fluctuations are due to Alfvénic waves but that intensity fluctuations come from a variety of sources, likely including fast and slow mode waves, as well as aperiodic variations. The relation between the velocity and intensity fluctuations differs depending on the underlying coronal structure. On short closed loops, the velocity and intensity fluctuations have similar power spectra and speeds. In contrast, on longer nearly radial trajectories, the velocity and intensity fluctuations have different power spectra, with the velocity fluctuations propagating at much faster speeds than the intensity fluctuations. Considering the temperature sensitivity of COMP, these longer structures are more likely to be closed fields lines of the quiet Sun rather than cooler open field lines. That is, we find the character of the interactions of Alfvénic waves and density fluctuations depends on the length of the magnetic loop on which they are traveling.https://doi.org/10.3847/1538-4357/adc1c0Quiet sunSolar physicsSolar coronal wavesQuiet solar coronaAtomic spectroscopyTime series analysis |
| spellingShingle | Michael Hahn Xiangrong Fu Stefan J. Hofmeister Yifan Huang Alexandros Koukras Daniel Wolf Savin Velocity and Density Fluctuations in the Quiet Sun Corona The Astrophysical Journal Quiet sun Solar physics Solar coronal waves Quiet solar corona Atomic spectroscopy Time series analysis |
| title | Velocity and Density Fluctuations in the Quiet Sun Corona |
| title_full | Velocity and Density Fluctuations in the Quiet Sun Corona |
| title_fullStr | Velocity and Density Fluctuations in the Quiet Sun Corona |
| title_full_unstemmed | Velocity and Density Fluctuations in the Quiet Sun Corona |
| title_short | Velocity and Density Fluctuations in the Quiet Sun Corona |
| title_sort | velocity and density fluctuations in the quiet sun corona |
| topic | Quiet sun Solar physics Solar coronal waves Quiet solar corona Atomic spectroscopy Time series analysis |
| url | https://doi.org/10.3847/1538-4357/adc1c0 |
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