Modeling the UV/EUV and its relevance for PROBA2 observations
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Modeling the UV/EUV and its relevance for PROBA2
observationsMargit Haberreiter
Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center, Davos, Switzerland
andLaboratory for Atmospheric and Space Physics, University of
Colorado, USA
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EUV spectrum
• Wavelengths –UV: 120 – 400 nm–EUV: 10 – 120 nm
• Contribution from the – Chromophere– Transition region – Corona
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Solar Modeling(SolMod – continuation of SRPM)
• Multi level atoms– 373 ions, from H to Ni with ioncharge 25– ~14’000 atomic levels– ~170’000 spectral lines – Statistical equation is solved to get the level populations
• Chromosphere and transition region – for ioncharge 2: – full NLTE (Fontenla et al., 2006; 2007; 2009)– plus optically thin transition region lines– Spherical symmetry
• Corona– ioncharge >2 – optically thin, i.e. collisions and spontaneous emission– Line of sight integration accounts for opacity– Spherical symmetry
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Masks from Precision Solar Photometric Telescope
Disk mask on 2005/9/12 obtained from PSPT data, Mauna Loa, Hawaiihttp://lasp.colorado.edu/pspt_access/
(R) Sunspot Penumbra(S) Sunspot Umbra(P) Faculae(H) Plage(F) Active network(D) Quiet network (white)(B) Intergranular Cells
Determined by the contrast as a function of the position on the disk-Only possible with respect to a -normalized quiet Sun intensity
Continuum, 607 nm (PICARD)
Ca II 393.4, FWHM=0.27nm
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0.1 1 10 100 1 103 1 104 1 105
4000
6000
8000
B 1001D 1002F 1003H 1004P 1005
B 1001D 1002F 1003H 1004P 1005
Pressure (dyn cm^-2)
Tem
pera
ture
(K) Faculae
PlageActive networkQuiet networkIntergranular Cells
Fontenla et al., 2009, ApJ 707, 482-502
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G-Band of CH molecular lines
Fontenla et al., 2009, ApJ 707, 482-502
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Violet CN Band
Fontenla et al., 2009, ApJ 707, 482-502
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600 800 1000 1200 1400 16001
10
100
1000
10000
100000 SUMER QS SRPM QS
Rad
ianc
e (m
W/m
^2/A
/sr)
Wavelength (A)
1
10
100
1000
10000
100000
B D F H P
Fontenla, Curdt, Haberreiter, et al., 2009, ApJ
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Modeling the EUVe.g. Fe XV 284 Å
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Coronal models
5 104 1 105 1.5 105 2 105
1 106
2 106
3 106
SRPM - Quiet Sun ISRPM - Quiet Sun IISRPM - Quiet Sun IIISRPM - Network RegionSRPM - Active RegionCranmer - Equatorial HoleCranmer - Active RetionCranmer - Polar Region
Height (km)
Tem
pera
ture
(K)
•SRPM Models are based on Doschek (1997), ApJ, 476, 903, Singh et al., 1982, J. Astrophys. 3, 249
•Cranmer et al, 2007, ApJS 171, 520
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Coronal lines and Bremsstrahlung
50 100 1501 10 8
1 10 7
1 10 6
1 10 5
1 10 4
1 10 3
0.01
0.1
1SRPM Quiet Sunconvolved spectrum
Wavelength (nm)
Irrad
ianc
e (W
m-2
nm
-1)
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Spectrum from Corona, TR and Chromosphere
50 1001 10 7
1 10 6
1 10 5
1 10 4
1 10 3
0.01
0.1
1SPRM 1SPRM 2SPRM 3SPRM 4SPRM 5
Wavelength (nm)
Irrad
ianc
e (e
rg c
m-2
s-1
nm-1
)
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SPRM calculation versus the EVE spectrum
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EVE calibration spectrum versus calculated spectrum
Haberreiter and Fontenla, 2009, AIP conference seriesEVE rocket calibration flight: Chamberlin et al., 2009, GRL
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Quiet Sun versus Coronal Hole
10 20 30 401 10 3
0.01
0.1
1
10
100
1 103
1 104
1 105SRPM Corona 1011Klimchuk loop modelCranmer Equatorial Hole
Wavelength (nm)
Inte
nsity
(erg
/cm
2/s/A
)
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Spherical SymmetryAllows the calculation of intensities at and beyond the limb
(e.g. Haberreiter et al. 2008)
Account for corona over 2 x area of solar disk
Adopted from Mihalas, 1978
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Spherical symmetry
28.4 28.41 28.42
5 10 3
0.01
sphericalplane-parallel
Wavelength (nm)
Irrad
ianc
e (W
m-2
nm
-1)
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Spherical geometry EIT 171 Å
170 170.5 171 171.5 1720
50
100
150
r/R = 0r/R=0.9r/R=1.00r/R=1.11r/R=1.34r/R=1.34
Wavelength (A)
Inte
nsity
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SOHO/EIT images
284 Angstroms171 Angstroms
195 Angstroms 304 Angstroms
Fe XII 1.3x105 K He II 8x104 K
He II 30.4 nm
Fe XV 28.4 nm
Fe IX 17.1 nm
Fe XII 19.5 nm
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EIT wavelengths
EVE spectrumSRPM calculation
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EIT passbands
Fe IX 17.1 nm
Fe XII 19.5 nm
Fe XV 28.4 nm
He II 30.4 nm
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29 30 31 321 10 7
1 10 6
1 10 5
1 10 4
1 10 3
0.01
0.1
1
10SRPM Quiet SunEVE rocket spectrum
Wavelength (nm)
Irrad
ianc
e (W
m-2
nm
-1)
He II 30.4 nm – high resolution
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Optical depth• Fe XV 17.1 nm:
– Disk center: max = 0.06
– Limb: (r=1.02): max = 0.63 (~900,000K)
• Fe XV 19.5 nm: – Disk center: max = 0.06
– Limb: (r=1.02): max = 0.34 (~1,100,000K)
• Fe XV 28.4 nm: – Disk center: max = 0.39– Limb: (r=1.02): max = 0.88 (~2,000,000K)
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LYRA passbands
LYRA CH 3: 17-80 nmLYRA CH 4: 6-20 nm
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LYRA measure-
ments April 2010
Courtesy, Ingolf Dammaschs
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LYRA measure-
ments May 2010
Courtesy, Ingolf Dammaschs
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Understand the daily variations of the UV/EUV
• Determine the solar cycle variation of solar activity features (with an emphasis on coronal holes) → create masks similar to PSPT masks
• Model the variation of the solar spectrum in the EUV
• Is there a long-term trend of the solar spectral irradiance (due to coronal holes)
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Questions to address• Understand the spectral variability
• Do all the spectral lines behave similarlyOR
• Increase of line strength of some lines and a decrease of others?
• Is a decrease in the EUV responsible for the decrease in TSI for the current minimum
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1. Variability of solar activity features
EIT 17.1nm07/01/2005
EIT 19.5 nm10/01/2002
EIT 28.4 nm10/10/2003
EIT 30.4 nm07/10/2006
coronal holes – quiet Sun – quiet coronal network – active coronal network - hot loop – super hot loop
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EIT image analysis• Radial dependence for outer corona• Thresholds based on intenstiy histogram
of the EIT images• Maximum value of histogram varies with
solar cycle (in particular for 284 Ǻ)• Coronal hole intensity changes with solar
cycle – (Barra et al., 2009)→ identification of coroanl features not trivial
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Area coverage of features
Data from Barra et al, 2009
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3. Determine the long-term trend of the solar spectral irradiance
The SOHO/SEM measurements indicate a decrease in the EUV by15%
Uncertainty ~ 6%
Not explained by F10.7 or sunspot number
What is the role of coronal holes?
Didkovsky et al., 2009
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Conclusions• Good agreement between the synthetic
spectra and the observed EVE quiet Sun spectrum
• An enourmous amount of spectral lines is contained in broader spectral bands
• Strong interest in SWAP images for the reconstruction of LYRA observations
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Questions?