SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Element Abundance Results from CDS Dr Peter Young Dr Peter Young SOHO/CDS Project Scientist CCLRC Rutherford Appleton Laboratory

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Why are abundances interesting? Fractionation found to occur in corona and solar windFractionation found to occur in corona and solar wind –related to FIP of element –magnitude depends on type of solar feature Stellar X-ray spectra have revealed an inverse FIP effect in active starsStellar X-ray spectra have revealed an inverse FIP effect in active stars Photospheric abundances have been revised recently leading to problems for standard solar modelPhotospheric abundances have been revised recently leading to problems for standard solar model

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL The FIP effect FIP - “First Ionization Potential”FIP - “First Ionization Potential” Low-FIP (≤ 10 eV) elements enhanced relative to high-FIP elements in corona and solar windLow-FIP (≤ 10 eV) elements enhanced relative to high-FIP elements in corona and solar wind Factor varies relative to solar feature, e.g.,Factor varies relative to solar feature, e.g., –fast solar wind: 2 –slow solar wind: 4-5 –coronal structures: up to 10-15

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Abundances with CDS NIS covers two wide wavelength bands covering consecutive ion stages for several elementsNIS covers two wide wavelength bands covering consecutive ion stages for several elements ElementFIP/eVStages Log T range Oxygen13.6II-V Neon21.6IV-VII Magnesium7.6V-X Silicon8.2VIII-XII Iron7.9X-XVI

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Abundance Methods Simple methodSimple method –find two ions formed at the same temperature –intensity ratio proportional to abundance ratio Complicated methodComplicated method –use line intensities from many ions to create DEM –abundances varied to ‘improve’ fit

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Mg/Ne Abundance in Quiet Sun Measurements of the FIP effect in the quiet Sun were difficult with previous instrumentation (Skylab) and SUMERMeasurements of the FIP effect in the quiet Sun were difficult with previous instrumentation (Skylab) and SUMER Isolated measurements using CDS performed by Del Zanna, Landi, MacPherson, YoungIsolated measurements using CDS performed by Del Zanna, Landi, MacPherson, Young –suggest FIP enhancement of 1 – 2 AIM: perform definitive measurements of Mg/Ne ratio in quiet Sun regions over a 2 year periodAIM: perform definitive measurements of Mg/Ne ratio in quiet Sun regions over a 2 year period

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL CDS observations Quiet Sun spectral atlas (NISAT) every week of missionQuiet Sun spectral atlas (NISAT) every week of mission 20” x 240” spatial area20” x 240” spatial area Only consider regions away from bright points and ARsOnly consider regions away from bright points and ARs Data from 1996 March to 1998 JuneData from 1996 March to 1998 June

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Analysis procedure Complete NIS spectra for supergranule cell centre and network regions extracted based on O V imageComplete NIS spectra for supergranule cell centre and network regions extracted based on O V image Emission lines of Ne IV-VII and Mg V-VIII identified and fit with Gaussian profilesEmission lines of Ne IV-VII and Mg V-VIII identified and fit with Gaussian profiles

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Analysis procedure Minimization procedure applied by specifying plasma column depths, d, over log T = [5.0,6.1], 0.1 intervalsMinimization procedure applied by specifying plasma column depths, d, over log T = [5.0,6.1], 0.1 intervals d 1, d 2, d 3 values at log T = 5.0, 5.6, 6.1d 1, d 2, d 3 values at log T = 5.0, 5.6, 6.1 Other values obtained by linear interpolationOther values obtained by linear interpolation CHIANTI/v4.2 used to compute line emissivitiesCHIANTI/v4.2 used to compute line emissivities Ab(Mg)/Ab(Ne), d 1, d 2, d 3 are the 4 free parametersAb(Mg)/Ab(Ne), d 1, d 2, d 3 are the 4 free parameters

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Abundance results

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Abundance results Average enhancements over photospheric Mg/Ne value:Average enhancements over photospheric Mg/Ne value: –Network: 1.25 ± 0.10 –Cell centres: 1.66 ± 0.23 Cell centres clearly show stronger enhancementCell centres clearly show stronger enhancement More details see Young (2005, A&A, 439, 361)More details see Young (2005, A&A, 439, 361)

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Interpretation Results consistent with cartoon of H. Peter (2001)Results consistent with cartoon of H. Peter (2001) Small fraction of quiet Sun connects to solar windSmall fraction of quiet Sun connects to solar wind Closed quiet Sun loops show photospheric abundancesClosed quiet Sun loops show photospheric abundances

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Active regions A striking feature of ARs are bright points with strongly enhanced transition region linesA striking feature of ARs are bright points with strongly enhanced transition region lines One class of such brightenings have very strong Mg linesOne class of such brightenings have very strong Mg lines

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Emerging AR, June 1996 AR 7968

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Emerging AR, June 1996 Inner brightenings in region of flux emergenceInner brightenings in region of flux emergence Outer brightenings at base of large coronal loopsOuter brightenings at base of large coronal loops

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Conclusions Central brightenings show photospheric Mg/Ne ratioCentral brightenings show photospheric Mg/Ne ratio Loop footpoints show factor 10 enhancement in Mg/NeLoop footpoints show factor 10 enhancement in Mg/Ne More details see Young & Mason (1997, Sol. Phys., 175, 523)More details see Young & Mason (1997, Sol. Phys., 175, 523)

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Future Work General Mg/Ne results for ARsGeneral Mg/Ne results for ARs Ne/O abundanceNe/O abundance Minor elements: Ar, K, CaMinor elements: Ar, K, Ca

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL General Mg/Ne results for ARs Widing & Feldman (2001, ApJ) found magnitude of FIP effect related to age of active region using Skylab dataWiding & Feldman (2001, ApJ) found magnitude of FIP effect related to age of active region using Skylab data With CDS it should be possible to look at variation in individual AR structuresWith CDS it should be possible to look at variation in individual AR structures

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL General Mg/Ne results for ARs

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Ne/O relative abundance Recent downward revisions of C, N, O & Ne abundances have caused problems for standard solar modelRecent downward revisions of C, N, O & Ne abundances have caused problems for standard solar model Drake & Testa (2005, Nature) suggested solar Ne/O ratio is in errorDrake & Testa (2005, Nature) suggested solar Ne/O ratio is in error

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Ne/O relative abundance Including oxygen in the quiet Sun Mg/Ne analysis:Including oxygen in the quiet Sun Mg/Ne analysis: photospheric Drake & Testa QS network

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Minor Elements: K, Ar, Ca PotassiumPotassium –K VIII λ519.4, K IX λ621.4 ArgonArgon –Ar VII λ585.8 CalciumCalcium –Ca VII λ551.4, Ca VIII λ596.9, Ca X λ557.7

SOHO/CDS CDS Users’ Meeting, Sep 2005 Dr Peter Young, CCLRC/RAL Future Missions Solar-B/EISSolar-B/EIS –ideal for coronal abundances –Fe/S, Ar/Ca Solar OrbiterSolar Orbiter –high spatial resolution for studying individual structures –Ne/Ca?