Emission measure distribution from the analysis of coronal data Fabio Reale Dipartimento di Scienze Fisiche & Astronomiche Università di Palermo, Italy E-mail: [email protected] Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Summary DEM of quiescent loops from SoHO/CDS data: Hot active region loop Cooler (TRACE) loop: multi-wavelength DEM of flaring loops from Yohkoh/SXT data Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 DEM of quiescent loops History of DEM saga: Use spectroscopy to derive thermal structure: DEM reconstruction Wide DEM indicates multi-thermal fibrils, thin DEM monolithic loops DEM reconstruction shows single line ratios bias (Schmelz et al. 2001) Debate on DEM reconstruction (Schmelz 2002, Martens et al. 2002, Aschwanden 2002, Schmelz et al. 2003): different results, problem of background subtraction T Schmelz et al. 2001 Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Debate on loop DEM DEM multiplicity (Schmelz et al. 2005): Analysis of a loop on the limb (CDS/SoHO) Multi-thermal structure at three locations: apex, left and right leg Different from other hot loops looking isothermal (Di Giorgio et al. 2003, Landi & Landini 2004) CDS atlas reveals many examples of both types of loops: different heating mechanisms? Di Giorgio et al. 2003 Schmelz et al. 2005 Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 DEM of an active region loop (Di Giorgio et al. 2003) Analysis of a SoHO/CDS observation of active region loops (14 rasters) Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 The CDS data Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Quantitative analysis: strip enclosing the loop Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 DEM at the apex sector (raster 4) Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Cooler quiescent loop (Reale & Ciaravella 2005, A&A, submitted) Rationale: Investigate how far one can go with present loop observations TRACE-selected loop Multi-wavelength observation Time-resolved observation Images Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 The observation Morphology (TRACE-based selection): Whole loop visible: OK (171 A filter) Bright: OK Isolated: half On the disk: OK (+230”, +470”) Long-lived (> 2 hours), slowly variable Length: ~1010 cm Multi-band observation: TRACE: Filters: 171 A, 195 A, 284 A 32x3 frames (1024x1024, 3.5 hours) Pixel size: 0.5” SoHO/CDS: Two relevant rasters (i.e. no time resolution) 11 relevant lines (5.9 < logT <6.4) Pixel size: 2.5” Yohkoh/SXT: Nine 512x512 frames (8 AlMg + 1 Al.1) Pixel size: 5” Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale L RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 The observation Time coverage (13 May 1998): TRACE: 6:30-10:00 UT Yohkoh/SXT: 6:30-8:40 UT SoHO/CDS: 7:50-8:46 UT (Raster 1) 10:23-12:12 UT (Raster 2) TRACE SXT CDS 6:30UT Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana 12:30UT Fabio Reale L RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 The loop life TRACE Animations: Time-interpolated images (~3.5 hours) Background subtracted (see below) The loop is slowly variable: The brightness distribution changes It fades away Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 TRACE: Data processing Pre-processing: trace_prep,wave2p,unspike,destr,derip,new_avg Alignment: for each filter Cross-correlation (align_cube_correl) Background subtraction: Since the loop disappears at the end of the sequence, we use the last frame (for each filter) as background Subtract the last frame from all others Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 TRACE: 171 A Raw images: Loop: Some filamentation but globally coherent evolution best visible after 1 hour then it fades Bkg-sub images: Enhanced loop contrast Asymmetric evolution: Right leg first Left leg later Slow fading Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Yohkoh/SXT Data processing: Sxt_prep,/register,/vignette Cross-correlation alignment (w/ TRACE 284) Rebinning: pix=1 arcsec Background subtraction: same as TRACE (AlMg only: no temperature diagnostics) Raw images: Similar to TRACE 284 A Loop confused inside an arcade? Bkg-sub images: The loop shows up The loop fades Overlaps TRACE loop Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 171 195 284 TRACE vs Yohkoh SXT The loops overlap quite well Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Filter ratio maps: 195/171 Temperature indicator Moderate structuring along and across the loop Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 The loop analysis Strip along the loop Strip divided into sectors Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Light curves e-folding decay time: ~3000 s Hotter plasma decays sooner Thermodynamic loop decay time (Serio et al. 1991): th 120 L9 1600 s T7 with L94.2 and T70.1 Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Filter ratio profiles Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Del Zanna (http://loopbench.astropa.unipa.it) Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Filter ratio Filter ratio 195/171 Raw Bkg sub. Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Filter ratio evolution Two regions: Apex (upper points) Whole loop (lower) The loop cools down Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 SoHO/CDS: the data CDS Data Set 14 Rasters 07:13:15 12:11:58 UT 1: FOV too small 3-13: Spectral Range too narrow 2: 14: 07:50:09 - 08:46:02 LOOP 10:23:42 - 12:11:58 Background Calibration Phot/cm2/sec1/arcsec2/Å Background Subtraction: no loop in the last raster Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Loop Background Different FOV, Pixels, Spectral lines Aligned (align_cube_correl) Rebinned to TRACE Pixels size Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Most of the loop is visible in Ca X and Mg IX The whole loop is visible in Mg X and Si X Just the right end is visible in Si XII, Fe XIV and Fe XVI Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 CDS lines brightness distributions along the loop Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Emission Measure G(T) function Mazzotta et al. (1998) ionization equilibrium fractions Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Results Hottest: sector 9 Moderate width: Sharp hot side Smoother cool side Sector 2: unclear (overlapping structures) Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 TRACE vs CDS TRACE 171 A image degraded to CDS space resolution & “rasterized” Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 DEM of flaring loops from Yohkoh/SXT data General project: the Sun is our template of X-ray star For direct comparison with stellar data, we have to translate the solar data into the same passband and format of the stellar data We need the whole X-ray spectrum of the Sun: not available Our approach: Use full-disk space-resolved Yohkoh/SXT data (images in a few wide bands, moderate spectral information) Derive the EM distribution vs temperature of the whole corona Derive X-ray spectra Derive instrument-filtered X-ray spectra Put spectra at stellar distance Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 DEM from Yohkoh/SXT data From two simultaneous SXT images taken with different filters, derive the temperature and emission measure for each pixel in corona ~ simultaneous Yohkoh/SXT images through different filters From the two sets of T and EM values, rearrange and obtain the distribution of emission measure vs. temperature, EM(T): we divide the range of T detectable by the instrument (5.5 < Log T [K] < 8 K) into bins and sum up all the EM values within each “temperature bin” Temperature Emission Measure Derive Temperature and emission measure for each pixel Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo RESIK,RHESSI &SPIRIT workshop INAF/Osservatorio Astronomico G.S. Vaiana Wroclaw 6-8 Dec 2005 (Orlando et al., 2000; Peres et al., 2000):Fabio Reale Whole-Disk EM(T) Distributions (Peres, Orlando, Reale, Rosner, Hudson 2000) Flares (Reale, Orlando & Peres 2001) Selection: from C to X-class Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Flare selection: well-observed Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Flare DEM evolution from SXT data Be and thick Al filter bands Flare evolution (time: pale to dark) vs background (quiet/active) corona Result: well-defined peak, small temperature change, larger EM change Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 If we include more filters…. … the DEM becomes flatter on the cool side Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 The X-class flare 2-Nov-92, 13:11, AlMg Overall Small dependence of T on class X-class: broader and hotter Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Synthesis of flare X-ray spectra Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 THE END Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 DEM of flaring loops: A different approach Preface: The Sun is our star template The Sun is our corona template We resolve the Sun vs we don’t resolve stars Questions: Can we use the Sun as a “meter” to “measure” stellar coronae? Can we use the Sun as a guide to study the stellar coronae Answer: YES, but we have to translate the solar data into stellar data Our approach: Use full-disk space-resolved Yohkoh/SXT data (images in a few wide bands, moderate spectral information) Derive the EM distribution vs temperature of the whole corona Derive X-ray spectra Derive instrument-filtered X-ray spectra Put spectra at stellar distance Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 From the EM(T) Distr. to the Coronal Spectrum … to the X-ray Spectrum of the Sun as a Star 6-Jan-92 D = 1 pc t_exp = 5 104 sec Spectral Synthesis (MEKAL) Chandra/ACIS Folding the synthetic spectrum through the instrument response From … to the the X-ray EM(T) Spectrum Distr. to of thethe Coronal Sun as Spectrum a Star 6-Jan-92 D = 1 pc t_exp = 2e5 sec Chandra/ACIS Palermo, 14 Sept., 2004 TRACE: 195 A Raw images: More bright structures Loop visible since the beginning Bkg-sub images: Steadily uniform brightness Gradual fading Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 TRACE: 284 A Raw images: Bright T-like structure Loop is faint Bkg-sub images: Loop faint but visible (right leg) Faster fading Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Yohkoh/SXT Field of view Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Emission profiles 171 A Raw Bkg sub Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana 171 A Fabio Reale 195 A 284 A RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Filter ratio HR 195/171 Raw Bkg sub. Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 The hot loop Let’s focus on the hot loop (Fe XVI): loop A Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 Multi-wavelength TRACE-selected loop (Reale & Ciaravella 2005, A&A, submitted) Selection in: list of SoHO campaigns (http://sohodata.nascom.nasa.gov) Selection made by: F. Reale SoHO campaign: 5170 Date: 13 May 1998 Name: Active region study Coordinator: Robert Walsh Rationale: Investigate how deep one can go with present loop observations Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005 TRACE: Data processing Pre-processing: trace_prep,wave2p,unspike,destr,derip,new_avg Alignment: for each filter Cross-correlation (align_cube_correl) Background subtraction: Since the loop disappears at the end of the sequence, we use the last frame (for each filter) as background Subtract the last frame from all others Pros: In principle, very accurate No interpolation Pixel-by-pixel Analyze all loop pixels Cons: Assumes no background evolution (13% variations on average) Possible variations of crossing structures Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo INAF/Osservatorio Astronomico G.S. Vaiana Fabio Reale RESIK,RHESSI &SPIRIT workshop Wroclaw 6-8 Dec 2005