| Issue |
A&A
Volume 374, Number 3, August II 2001
|
|
|---|---|---|
| Page(s) | L21 - L24 | |
| Section | Letters | |
| DOI | https://doi.org/10.1051/0004-6361:20010872 | |
| Published online | 15 August 2001 | |
The size of penumbral fine structure
Sterrenkundig Instituut Utrecht, Postbus 80 000, 3507 TA Utrecht, The Netherlands
Received:
21
May
2001
Accepted:
19
June
2001
I present power spectra of penumbral and granular intensity
variations from a speckle-restored G-band image sequence of sunspot
NOAA 9407 taken on April 1, 2001 with the Dutch Open Telescope on La
Palma. I compare spatial power spectra of the sunspot penumbra with
spatial power spectra from granulation with and without filigree.
Relative to the granular power distribution, the penumbral power
spectrum is enhanced over a wide range in spatial frequency peaking at
0
35. For smaller scales, the penumbral power distribution
closely resembles that of the granular intensity variations. In
contrast, the power spectrum of granulation with filigree exhibits
increased power down to the resolution limit of 022, indicating
the presence of unresolved magnetic elements.
Key words: Sun: magnetic fields / sunspots
© ESO, 2001
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