Polytropic Behavior in Corotating Interaction Regions: Evidence of Alfvénic Heating

Corotating interaction regions (CIRs) are recurring structures in the solar wind, characterized by interactions between fast and slow solar wind streams that compress and heat plasma. This study investigates the polytropic behavior of distinct regions in and around CIRs: uncompressed slow solar wind...

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Main Authors: M. A. Dayeh, M. J. Starkey, G. Livadiotis, S. T. Hart, A. A. Shmies, R. C. Allen, R. Bučik, H. A. Elliott
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
Subjects:
Online Access:https://doi.org/10.3847/2041-8213/adc4d7
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author M. A. Dayeh
M. J. Starkey
G. Livadiotis
S. T. Hart
A. A. Shmies
R. C. Allen
R. Bučik
H. A. Elliott
author_facet M. A. Dayeh
M. J. Starkey
G. Livadiotis
S. T. Hart
A. A. Shmies
R. C. Allen
R. Bučik
H. A. Elliott
author_sort M. A. Dayeh
collection DOAJ
description Corotating interaction regions (CIRs) are recurring structures in the solar wind, characterized by interactions between fast and slow solar wind streams that compress and heat plasma. This study investigates the polytropic behavior of distinct regions in and around CIRs: uncompressed slow solar wind, compressed slow solar wind, compressed fast solar wind, and uncompressed fast solar wind. Using Wind spacecraft data and an established methodology for calculating the polytropic index ( γ ), we analyze 117 CIR events. Results indicate varying γ values across regions, with heating observed in compressed regions driven by Alfvén wave dissipation originating from fast streams. In the uncompressed fast solar wind, γ exceeds adiabatic values the most and correlates well with strong Alfvénic wave activity.
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spelling doaj-art-dbb2b43f92454ca39d2bd76cf794d28a2025-08-20T02:20:26ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019841L3310.3847/2041-8213/adc4d7Polytropic Behavior in Corotating Interaction Regions: Evidence of Alfvénic HeatingM. A. Dayeh0https://orcid.org/0000-0001-9323-1200M. J. Starkey1https://orcid.org/0000-0001-7514-6571G. Livadiotis2https://orcid.org/0000-0002-7655-6019S. T. Hart3https://orcid.org/0000-0003-0508-4912A. A. Shmies4https://orcid.org/0009-0000-9334-0116R. C. Allen5https://orcid.org/0000-0003-2079-5683R. Bučik6https://orcid.org/0000-0001-7381-6949H. A. Elliott7https://orcid.org/0000-0003-2297-3922Southwest Research Institute , San Antonio, TX 78238, USA ; maher.aldayeh@swri.org; University of Texas at San Antonio , San Antonio, TX 78249, USASouthwest Research Institute , San Antonio, TX 78238, USA ; maher.aldayeh@swri.orgPrinceton University , Princeton, NJ 08544, USASouthwest Research Institute , San Antonio, TX 78238, USA ; maher.aldayeh@swri.orgSouthwest Research Institute , San Antonio, TX 78238, USA ; maher.aldayeh@swri.org; University of Texas at San Antonio , San Antonio, TX 78249, USASouthwest Research Institute , San Antonio, TX 78238, USA ; maher.aldayeh@swri.orgSouthwest Research Institute , San Antonio, TX 78238, USA ; maher.aldayeh@swri.orgSouthwest Research Institute , San Antonio, TX 78238, USA ; maher.aldayeh@swri.org; University of Texas at San Antonio , San Antonio, TX 78249, USACorotating interaction regions (CIRs) are recurring structures in the solar wind, characterized by interactions between fast and slow solar wind streams that compress and heat plasma. This study investigates the polytropic behavior of distinct regions in and around CIRs: uncompressed slow solar wind, compressed slow solar wind, compressed fast solar wind, and uncompressed fast solar wind. Using Wind spacecraft data and an established methodology for calculating the polytropic index ( γ ), we analyze 117 CIR events. Results indicate varying γ values across regions, with heating observed in compressed regions driven by Alfvén wave dissipation originating from fast streams. In the uncompressed fast solar wind, γ exceeds adiabatic values the most and correlates well with strong Alfvénic wave activity.https://doi.org/10.3847/2041-8213/adc4d7Space plasmasPolytropesCorotating streams
spellingShingle M. A. Dayeh
M. J. Starkey
G. Livadiotis
S. T. Hart
A. A. Shmies
R. C. Allen
R. Bučik
H. A. Elliott
Polytropic Behavior in Corotating Interaction Regions: Evidence of Alfvénic Heating
The Astrophysical Journal Letters
Space plasmas
Polytropes
Corotating streams
title Polytropic Behavior in Corotating Interaction Regions: Evidence of Alfvénic Heating
title_full Polytropic Behavior in Corotating Interaction Regions: Evidence of Alfvénic Heating
title_fullStr Polytropic Behavior in Corotating Interaction Regions: Evidence of Alfvénic Heating
title_full_unstemmed Polytropic Behavior in Corotating Interaction Regions: Evidence of Alfvénic Heating
title_short Polytropic Behavior in Corotating Interaction Regions: Evidence of Alfvénic Heating
title_sort polytropic behavior in corotating interaction regions evidence of alfvenic heating
topic Space plasmas
Polytropes
Corotating streams
url https://doi.org/10.3847/2041-8213/adc4d7
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