Energy transport in the solar transition layer

Abstract

Restricted accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Ashbourn J. M. A. and Woods L. C. 2001Energy transport in the solar transition layerProc. R. Soc. Lond. A.4571873–1888http://doi.org/10.1098/rspa.2001.0791SectionRestricted accessResearch articleEnergy transport in the solar transition layer J. M. A. Ashbourn J. M. A. Ashbourn Mathematical Institute, University of Oxford, 24–29 St Giles', Oxford OX1 3LB, UK Google Scholar Find this author on PubMed Search for more papers by this author and L. C. Woods L. C. Woods Mathematical Institute, University of Oxford, 24–29 St Giles', Oxford OX1 3LB, UK Google Scholar Find this author on PubMed Search for more papers by this author J. M. A. Ashbourn J. M. A. Ashbourn Mathematical Institute, University of Oxford, 24–29 St Giles', Oxford OX1 3LB, UK Google Scholar Find this author on PubMed Search for more papers by this author and L. C. Woods L. C. Woods Mathematical Institute, University of Oxford, 24–29 St Giles', Oxford OX1 3LB, UK Google Scholar Find this author on PubMed Search for more papers by this author Published:08 July 2001https://doi.org/10.1098/rspa.2001.0791AbstractWe have developed a theory for the differential emission measure ϵ in the solar transition layer, which has a temperature in the range 104K < T < 106K. On comparing the resulting log ϵ versus log T plot with curves derived from observations, we find good agreement over the whole range. As heat flows down from the coronal reservoir, the vertical temperature gradient T′ increases until it reaches a critical value, T′m, beyond which any further increase takes the heat flux in the electron gas parallel to the magnetic field (qe||) above the value that could be convected by the electrons drifting at the ion sound speed Cs. This gradient is reached at about the midpoint of the temperature range and we infer that as a consequence the ionacoustic instability generates turbulence in the ion gas; this substantially increases the effective collision frequencies in the ion fluid with the result that at about T = 105K, where T′ = T′m, the parallel electron heat flux and the perpendicular ion heat flux (qi⊥) are comparable. Below T = 105K, qi⊥ is dominant and gives rise to a slope in our plot of ca. -3.5, as observed, whereas above this temperature, qe|| dominates and the slope increases to ca. 1.5, as is also observed. Ohmic dissipation by the ion-sound limited current leads to a heating rate of the form AT−5/2, where the constant A depends on the unknown size of the flux tubes involved in the heat transport. Previous ArticleNext Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsCited by Judge P (2021) Magnetic Connections across the Chromosphere–Corona Transition Region, The Astrophysical Journal, 10.3847/1538-4357/abf8ad, 914:1, (70), Online publication date: 1-Jun-2021. Bahauddin S, Bradshaw S and Winebarger A (2020) The origin of reconnection-mediated transient brightenings in the solar transition region, Nature Astronomy, 10.1038/s41550-020-01263-2, 5:3, (237-245) Judge P and Centeno R (2008) On the Magnetic Structure of the Solar Transition Region, The Astrophysical Journal, 10.1086/590104, 687:2, (1388-1397), Online publication date: 10-Nov-2008. Ashbourn J and Woods L (2006) Circulating currents in magnetic flux tubes, Physica Scripta, 10.1088/0031-8949/74/3/008, 74:3, (349-352), Online publication date: 1-Sep-2006. This Issue08 July 2001Volume 457Issue 2012 Article InformationDOI:https://doi.org/10.1098/rspa.2001.0791Published by:Royal SocietyPrint ISSN:1364-5021Online ISSN:1471-2946History: Published online08/07/2001Published in print08/07/2001 License: Citations and impact Keywordsdifferential emission measureion-acoustic instabilitysolar transition layerenergy transport