Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
Emission measure distribution Emission measure distribution from the analysis of coronal from the analysis of coronal
datadataFabio Reale
Dipartimento di Scienze Fisiche & AstronomicheUniversità di Palermo, ItalyE-mail: [email protected]
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
Summary
DEM of quiescent loops from SoHO/CDS data:Hot active region loopCooler (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. VaianaFabio 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
Schmelz et al. 2001
T
DE
M
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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”
L
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale 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)
L
TRACE
SXT
CDS
6:30UT 12:30UT
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale 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. VaianaFabio 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 (Cross-correlation (align_cube_correlalign_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. VaianaFabio 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. VaianaFabio 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. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
TRACE vs Yohkoh
The loops overlap quite well
171 195 284 SXT
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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):
with L94.2 and T70.1
sT
Lth 1600120
7
9
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
Filter ratio profiles
Del Zanna(http://loopbench.astropa.unipa.it)
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio 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. VaianaFabio 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. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
CDS Data Set 14 Rasters 07:13:15 12:11:58 UT 1: FOV too small 3-13: Spectral Range too narrow 2: 07:50:09 - 08:46:02 LOOP 14: 10:23:42 - 12:11:58 Background
Calibration Phot/cm2/sec1/arcsec2/Å Background Subtraction:
no loop in the last raster
SoHO/CDS: the data
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
BackgroundLoop
Different FOV, Pixels, Spectral linesAligned (align_cube_correl)Rebinned to TRACE Pixels size
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
Most of the loop is visible in Ca X and Mg IXThe whole loop is visible in Mg X and Si XJust 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. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
DEM of flaring loopsfrom 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. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
~ simultaneous Yohkoh/SXT
images through different filters
Derive Temperature and emission measure for each pixel
Temperature Emission Measure
From two simultaneous SXT images taken with different filters, derive the temperature and emission measure for each pixel in corona
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”
(Orlando et al., 2000; Peres et al., 2000):
DEM from Yohkoh/SXT data
(Peres, Orlando, Reale, Rosner, Hudson 2000)
Whole-Disk EM(T) Distributions
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
Flares(Reale, Orlando & Peres 2001)
Selection: from C to X-class
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio 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. VaianaFabio 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. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
If we include more filters….
… the DEM becomes flatter on the cool side
The X-class flare
2-Nov-92, 13:11, AlMg
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
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. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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
From the EM(T) Distr. to the Coronal Spectrum
6-Jan-92
D = 1 pct_exp = 5 104 sec
… to the X-ray Spectrum of the Sun as a Star
Spectral Synthesis (MEKAL)
Chandra/ACIS
Folding the synthetic spectrum
through the instrument response
Palermo, 14 Sept., 2004
From the EM(T) Distr. to the Coronal Spectrum
Chandra/ACIS
6-Jan-92
D = 1 pct_exp = 2e5 sec
… to the X-ray Spectrum of the Sun as a Star
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
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. VaianaFabio 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. VaianaFabio 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. VaianaFabio Reale RESIK,RHESSI &SPIRIT workshop
Wroclaw 6-8 Dec 2005
Emission profiles
171 A
Raw
Bkg sub
195 A 284 A171 A
Dipartimento di Scienze Fisiche & Astronomiche – Universita’ di Palermo
INAF/Osservatorio Astronomico G.S. VaianaFabio Reale 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. VaianaFabio 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. VaianaFabio 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. VaianaFabio 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 (Cross-correlation (align_cube_correlalign_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