Modeling the UV/EUV and its relevance for PROBA2

observationsMargit Haberreiter

Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center, Davos, Switzerland

and

Laboratory for Atmospheric and Space Physics, University of Colorado, USA

EUV spectrum

• Wavelengths –UV: 120 – 400 nm

–EUV: 10 – 120 nm

• Contribution from the – Chromophere

– Transition region

– Corona

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

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

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

)

FaculaePlageActive networkQuiet networkIntergranular Cells

Fontenla et al., 2009, ApJ 707, 482-502

G-Band of CH molecular lines

Fontenla et al., 2009, ApJ 707, 482-502

Violet CN Band

Fontenla et al., 2009, ApJ 707, 482-502

600 800 1000 1200 1400 16001

10

100

1000

10000

100000 SUMER QS SRPM QS

Ra

dia

nce

(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

Modeling the EUVe.g. Fe XV 284 Å

Coronal models

5 104 1 10

5 1.5 105 2 10

5

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

Coronal lines and Bremsstrahlung

50 100 1501 10

8

1 107

1 106

1 105

1 104

1 103

0.01

0.1

1

SRPM Quiet Sunconvolved spectrum

Wavelength (nm)

Irra

dian

ce (

W m

-2 n

m-1

)

Spectrum from Corona, TR and Chromosphere

50 1001 10

7

1 106

1 105

1 104

1 103

0.01

0.1

1

SPRM 1SPRM 2SPRM 3SPRM 4SPRM 5

Wavelength (nm)

Irra

dian

ce (

erg

cm-2

s-1

nm

-1)

SPRM calculation versus the EVE spectrum

EVE calibration spectrum versus calculated spectrum

Haberreiter and Fontenla, 2009, AIP conference seriesEVE rocket calibration flight: Chamberlin et al., 2009, GRL

Quiet Sun versus Coronal Hole

10 20 30 401 10

3

0.01

0.1

1

10

100

1 103

1 104

1 105

SRPM Corona 1011Klimchuk loop modelCranmer Equatorial Hole

Wavelength (nm)

Inte

nsity

(er

g/cm

2/s/

A)

Spherical Symmetry

Allows 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

Spherical symmetry

28.4 28.41 28.42

5 103

0.01

sphericalplane-parallel

Wavelength (nm)

Irra

dian

ce (

W m

-2 n

m-1

)

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

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

EIT wavelengths

EVE spectrumSRPM calculation

EIT passbands

Fe IX 17.1 nm

Fe XII 19.5 nm

Fe XV 28.4 nm

He II 30.4 nm

29 30 31 321 10

7

1 106

1 105

1 104

1 103

0.01

0.1

1

10

SRPM Quiet SunEVE rocket spectrum

Wavelength (nm)

Irra

dian

ce (

W m

-2 n

m-1

)He II 30.4 nm – high resolution

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)

LYRA passbands

LYRA CH 3: 17-80 nmLYRA CH 4: 6-20 nm

LYRA measure-

ments April 2010

Courtesy, Ingolf Dammaschs

LYRA measure-

ments May 2010

Courtesy, Ingolf Dammaschs

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)

Questions to address

• Understand the spectral variability

• Do all the spectral lines behave similarly

OR• 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

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

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

Area coverage of features

Data from Barra et al, 2009

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

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

Questions?