Issue |
A&A
Volume 383, Number 1, FebruaryIII 2002
|
|
---|---|---|
Page(s) | 275 - 282 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361:20011685 | |
Published online | 15 February 2002 |
Fine structure and dynamics in a light bridge inside a solar pore
1
Institut für Geophysik, Astrophysik und Meteorologie, Universitätsplatz 5, 8010 Graz, Austria
2
Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
3
Astronomical Institute, Academy of Sciences of the Czech Republic, 25165 Ondřejov, Czech Republic
Corresponding author: J. Hirzberger, jkh@igam06ws.KFUnigraz.ac.at
Received:
24
August
2001
Accepted:
26
November
2001
A photometric analysis of the sub-structure of a granular
light bridge in a large solar pore is performed. The data
consist of a 66 min time series of white light images
( Å ± 50 Å) of an active region
NOAA 7886 obtained at the Swedish Vacuum Solar Telescope on La Palma,
Canary Islands. The light bridge can be resolved into an
assembly of small grains embedded in a diffuse background with an
intensity of about 85% of the mean photospheric intensity
(Iphot). Following the temporal evolution of these sub-structures
in their irregular motions inside the light bridge, proper motions
with velocities up to 1.5 km s-1 can be detected. Their lifetime
distribution shows a maximum at 5 min and a second peak at
approximately 20 min. The origin and the decay of these sub-structures
is very similar to those of granules, i.e. fragmentation, merging and
spontaneous origination from, and dissolution into, the background can be
observed. Some of them are able to escape from the light bridge
into the umbra where they cannot be distinguished from adjacent
umbral dots. Generally, this study presents evidence that the
observed phenomenon represents convective motions.
Key words: Sun: granulation / Sun: photosphere / sunspots / convection
© ESO, 2002
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