Download Loop - CBK PAN

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 L94.2 and T70.1
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