Observations of Fe I lines in the quiet solar photosphere
A. Kucera 1 2,
J. Rybák 1 and
H. Wöhl 2
1 Astronomical Institute, Slovak Academy of Sciences,
SK-05960 Tatranská Lomnica, Slovakia
2 Kiepenheuer-Institut für Sonnenphysik,
Schöneckstr. 6, D-79104 Freiburg, Germany
1995A&A...298..917K
Abstract
We investigate three sets of spectra with high spatial and spectral
resolution. Each set consists of four spectra taken simultaneously with
the Vacuum Tower Telescope at Izana, Tenerife. The main spectral
characteristics (continuum intensity I_c_; full width at half maximum
FWHM; residual intensity I_o_) were computed for 5 magnetic and
non-magnetic Fe I lines (5434.543 A, 5576.099 A, 6301.497 A, 6302.499 A,
6494.994 A). Our results allow a diagnosis of the solar atmosphere in
the vertical (two main levels of line formation) and horizontal
directions (71 arcseconds). The spectra cover both interior parts of
supergranular cells (purely quiet regions, PQR) and cell boundaries
(moderate active regions, MAR). The main results are: (1) We find a
different continuum intensity distribution for PQRs and MARs, which
reflects the existence of different patterns in these regions. The
difference is also evident in the rms residual intensity fluctuation.
(2) A significant minimum of the residual intensity fluctuations
({delta}I_o_/I_c_)_rms_ occurs at a height of about 300km. (3) At all
heights of the PQRs the line widths FWHM in the intergranular lanes are
larger than the mean line width; those in the granules are smaller. This
variation of the FWHM is influenced by a magnetic effect near the
centres of the intergranular lanes (reduced FWHM), and by the effect of
convection in granules (enhanced FWHM). (4) The correlation <I_c_,
I_o_> reverses its sign at a height of about 250km. The
anticorrelation in the range 300-500km indicates a non-convective
structure, different from the photospheric granular pattern found
earlier.