| Issue |
A&A
Volume 378, Number 1, October IV 2001
|
|
|---|---|---|
| Page(s) | 251 - 256 | |
| Section | Planets and planetary systems | |
| DOI | https://doi.org/10.1051/0004-6361:20011176 | |
| Published online | 15 October 2001 | |
Ba ii 4554 Å speckle imaging as solar Doppler diagnostic
1
Sterrekundig Instituut Utrecht, Postbus 80 000, 3508 TA Utrecht, The Netherlands e-mail: R.J.Rutten@astro.uu.nl
2
Institute of Solar-Terrestrial Physics, 664033 Irkutsk, PO Box 4026, Russia e-mail: skoal@iszf.irk.ru
Corresponding author: P. Sütterlin, P.Suetterlin@astro.uu.nl
Received:
12
July
2001
Accepted:
20
August
2001
We present observations testing the Dopplergram capability
of a narrow-band (80 mÅ) Lyot filter imaging the solar surface in the
wings of the Ba ii 4554 Å resonance line in combination with speckle
reconstruction to obtain high angular resolution. The Ba ii line is
found to be an excellent tool for high-resolution Doppler mapping
thanks to opacity insensitivity to temperature variations and
line-width insensitivity to thermal broadening. The resulting
Dopplergrams show concentrated downflows of 1.2-2.2 km
s-1 in
intergranular lanes that probably mark magnetic fluxtubes.
Two-wavelength profile sampling is found to suffice for
high-resolution Dopplergram construction. The filter will be
installed as part of a multi-wavelength speckle imaging system on the
new Dutch Open Telescope.
Key words: Sun: atmosphere / Sun: photosphere / Sun: faculae, plages / techniques: image processing / instrumentation: miscellaneous
© ESO, 2001
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