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J/ApJ/707/482       Models of the solar atmosphere. III.       (Fontenla+, 2009)
Semiempirical models of the solar atmosphere.
III. Set of non-LTE models for Far-Ultraviolet/Extreme-Ultraviolet irradiance
computation.
    Fontenla J.M., Curdt W., Haberreiter M., Harder J., Tian H.
   <Astrophys. J., 707, 482-502 (2009)>
   =2009ApJ...707..482F
ADC_Keywords: Sun ; Models, atmosphere ; Ultraviolet

Keywords: solar-terrestrial relations - Sun: activity - Sun: atmosphere -
          Sun: chromosphere - Sun: faculae, plages - Sun: UV radiation

Abstract:
    Semiempirical atmospheric models of solar surface features as observed
    at moderate resolution are useful tools for understanding the observed
    solar spectral irradiance variations. Paper I described a set of
    models constructed to reproduce the observed radiance spectrum for
    solar surface features at ∼2 arcsec resolution that constitute an
    average over small-scale features such as granulation. Paper II showed
    that a revision of previous models of low-chromospheric inter-network
    regions explains the observed infrared CO lines in addition to the UV
    and radio continuum from submillimeter to centimetric wavelengths. The
    present paper (1) shows that the CaII H and K line wing observations
    are also explained by the new quiet-Sun-composite model, (2)
    introduces new low-chromospheric models of magnetic features that
    follow the ideas in Paper II (Fontenla et al. 2007ApJ...667.1243F),
    (3) introduces new upper chromospheric structures for all quiet-Sun
    and active-region models, and (4) shows how the new set of models
    explains EUV/FUV observations of spectral radiance and irradiance.
    This paper also discusses the chromospheric radiative-loss estimates
    in each of the magnetic features. The new set of models provides a
    basis for the spectral irradiance synthesis at EUV/FUV wavelengths
    based on the features observed on the solar surface.

Description:
    Observations by the SOHO/SUMER instrument have been used to produce
    the atlas of Curdt et al. (2001, Cat. J/A+A/375/591) showing the
    spectrum of the average quiet-Sun in the wavelength range
    700-1500Å. We use these observations for defining a set of
    atmospheric models based on the distribution of observed intensities
    at a few wavelengths.

    The quiet-Sun components are defined from the CaII K line intensity
    enhancements as described by Fontenla & Harder (2005MmSAI..76..826F).
    Observations of the solar disk in the CaII K line from several
    facilities are available. We currently use images obtained by the
    Precision Solar Photometric Telescope instrument at the Mauna Loa
    Solar Observatory (hereafter MLSO/PSPT). These data (see
    http://lasp.colorado.edu/pspt_access/) provide an almost continuous
    and accurate record since 2005 January and permit comparison of the
    computed with observed spectral irradiance.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
model1.dat       195       91  *Atmospheric model 1001; feature B
model2.dat       195       91  *Atmospheric model 1002; feature D - network
model3.dat       195       91  *Atmospheric model 1003; feature F - enhanced
                              network
model4.dat       195       91  *Atmospheric model 1004; feature H
model5.dat       195      101  *Atmospheric model 1005; feature P

Notes on *.dat: The units of all data are in the CGS system. Designation of
                features:
       ----------------------------------------------------------------
       Letter Model Feature description             Pressure   Disk
              Index                                   (a)       (b)
       ----------------------------------------------------------------
        B     1001  Quiet-Sun inter-network          0.235   <1.02
        D     1002  Quiet-Sun network lane           0.340    1.02-1.08
        F     1003  Enhanced network                 0.552    1.08-1.19
        H     1004  Plage (that is not facula)       1.00     1.19-1.43
        P     1005  Facula (i.e., very bright plage) 1.62     1.43-1.80
        S     1006  Sunspot umbra                    3.86
        R     1007  Sunspot penumbra                 2.10
       ----------------------------------------------------------------
        Note (a): Pressure at 2x105K(dyne/cm2)
        Note (b): Disk center contrast in CaII K MLSO/PSPT
       ----------------------------------------------------------------


See also:
  J/A+A/531/A173 : Spectroscopy of CaII-H line at solar limb (Beck+, 2011)
  J/A+A/493/1099 : CaII HK emission in rapidly rotating stars (Schroeder+, 2009)
  J/A+A/423/1109 : Center-to-limb variation of quiet Sun (Allende+, 2004)
  J/A+A/375/591  : SUMER Spectral Atlas of Solar Disk Features (Curdt+, 2001)
  J/A+AS/126/281 : Solar disk spectrum (660-1175A) (Curdt+ 1997)
  http://www.digidyna.com/ : Solar Radiation Physical Modeling page
  http://lasp.colorado.edu/pspt_access/ : Precision Solar Photometric Telescope


Byte-by-byte Description of file: model[12345].dat

   Bytes Format Units  Label   Explanations

   1-  3  I3    ---    Ind     [0,100] Index for the height (1)
   5- 24 E20.13 cm     h       [-1.1e+07,2.03933e+08] Altitude on the Sun
                               above an arbitrary reference point (2)
  27- 45 E19.13 K      T       [3790,201234] Temperature (3)
  48- 60  E13.7 cm-3   ne      [4.47707e+09,3.81523e+15] Electron density
  63- 75  E13.7 cm-3   np      [1.53999e+09,3.78703e+15] Proton density
  78- 90  E13.7 cm-3   na      [3769.84,1.40664e+17] Neutral hydrogen density
  93-105  E13.7 cm-3   nh      [3.7253e+09,1.43198e+17] Total hydrogen
                               density (4)
 108-120  E13.7 cm/s   vt      [52017,2.5e+06] Turbulence velocity (5)
 123-135  E13.7 cm/s2  accel   [644.870,7000] Non-gravitational acceleration (6)
 138-150  E13.7 ---    bH-     [0.439154,917.888] Departure from LTE
                               coefficient for H- (7)
 153-165  E13.7 ---    ---     [0,0] (vel)
 168-180  E13.7 ---    bH2     [0.554186,917.888] Departure from LTE
                               coefficient for H2 molecule (8)
 183-195  E13.7 ---    ---     [1,1] This value is always 1, and not relevant
                               here

Note (1): Note that these start at 0 and increasing index correspond to
          decreasing altitude.
Note (2): This reference point is close but not exactly at tau_5000=1.

Note (3): The models assume the electron and ion kinetic temperatures are
          described by this value.
Note (4): This value is always the sum of the previous two, but the listing
          numerical precision may make it slightly different.
Note (5): This value is used a microturbulent broadening velocity.

Note (6): This value is used for the pressure balance as described in the paper.

Note (7): The LTE is considered with respect to electron attachment,
          i.e. e+H←>H-+hν, but the calculation also considers other
          reaction channels.
Note (8): The LTE is considered with respect to H2 dissociation,
          i.e. H+H←>H2+hν, but the calculation also considers
          other reaction channels.


History:
    From electronic version of the journal

Acknowledgements:
    For questions please contact Juan M Fontenla at either
    fontenla{at}colorado.edu or johnf{at}digidyna.com

References:
    Fontenla et al. Paper I.  2006ApJ...639..441F
    Fontenla et al. Paper II. 2007ApJ...667.1243F
(End)                 Greg Schwarz [AAS], Emmanuelle Perret [CDS]    30-Dec-2011