FibrillarstructuresasmeansofenergytransportinthesolarchromosphereInacloseinternationalcollaboration,researchersattheUniversityofOslohavemovedonestepclosertounderstandingthemysteriousheatingoftheSun'satmosphere,thankstohigh-resolutionobservationsprovidedbyseveraladvancedfacilitiesaroundtheglobe.Inparticular,theresearchfocusesonthechromosphere,whichisahighlystructuredlayeroftheSun’satmosphere.Thislayerexhibitsfibrillarstructuresofdifferentphysicalproperties.Thesestructureshavebeenshowntobeagoodproxyforgeometryofthemagneticfields.Duetoinstrumentallimitations,thesefeatureshadbeenstudiedsofarinthe upper chromosphere and beyond, and less so in the lower heights from where the energy required for theatmosphericheatinglikelyoriginates.Now,astudyledbyDrShahinJafarzadehoftheUniversityofOslo,incollaborationwithscientistsfromtheMaxPlanckInstituteforSolarSystemResearchandfourotherinstitutionsinGermany,Spain,andUSA,hasusedhigh-resolutionimagesrecordedbytheSUNRISEballoon-bornesolarobservatory(seeFig.1)torevealforthefirsttimethatslenderfibrillarstructuresinthelowsolarchromospherecarryvariouskindsofmagnetohydrodynamicwavesthatareenergeticenoughtoheatthesolaratmosphere.

Furthermore, within another project funded by the European Research Council (ERC), Dr Jafarzadeh and hiscollaborators have exploitedmulti-height observations of the solar atmosphere from the Interface Region ImagingSpectrograph explorer (IRIS; a NASA space telescope), complemented by the first direct measurements of thechromospheric temperature with the Atacama Large Millimeter/submillimeter Array (ALMA; the world largestastronomical facility) tosuggest thatmanyof the thread-likestructuresarepossiblyextended,aseitherdiscreteorconnectedevents,throughouttheentiresolarchromosphereandbeyond.Thesecomplementarystudiesofthefibrillarstructuresathighresolutionprovideessentialinformationaboutoneofthe most promising means of the energy transport through the solar atmosphere. In summary, we find fibrillarstructuresinthesolarchromosphereasextendedwave-guideswhichchannelenergyintotheuppersolaratmosphere.Yetanewersolarinstrument‘CHROMIS’,whichhasrecentlybeeninstalledontheSwedish1-mSolarTelescope(SST)inLaPalma(Canaryislands,Spain),facilitatesmulti-layerobservationsoftheentiresolarchromosphereatpresentlythehighestresolution.Ultimately,suchobservationswillshedlightontheroleandthenatureoffibrillarstructuresinthesolarchromosphere.Myhomepageattheuniversity’swebsite(withlinkstomyrecentpapersandtoallinstrumentsIhavementionedabove):http://www.astro.uio.no/english/people/aca/shahinjContact:ShahinJafarzadeh(shahin.jafarzadeh@astro.uio.no)

Illustration 1: An image of the SUNRISE balloon just before its launch. Image credit: NASA