Issue |
A&A
Volume 384, Number 2, MarchIII 2002
|
|
---|---|---|
Page(s) | 460 - 472 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20020039 | |
Published online | 15 March 2002 |
The photometric behaviour of SU Dra, 1955–2000
Konkoly Observatory, PO Box 67, 1525 Budapest, XII, Hungary
Corresponding author: barcza@konkoly.hu
Received:
17
September
2001
Accepted:
7
January
2002
A multicolour photometric data basis is compiled for
SU Dra from 356 Johnson UBV and
228 observations reported in this paper, in addition to
483 BV, 289 UBV, and
85 UBVRI observations
found in the literature.
Mean period, period change
day/day,
and phase noise are derived from the V light curves
by a variational procedure minimizing the length of the folded
light curve (string length minimization, SLM). From variation of
string length in the neighbourhood of minimum, observational error
of photometry, observed amplitude, number of observations formulae
are derived for the error of period and phase noise by statistical
and analytical considerations. Secondary periodic variations
are excluded to a few mmag level, indication of amplitude variation
(Blazhko-effect) has not been found,
however, systematic segregation of light
curve segments is reported from different epochs in the descending
branch before the brightness rise. Mean light and colour curves are
derived from photometry and they are compared with those
from integration of spectrophotometric
observations. The period change is interpreted in terms of mixing
events in the stellar interior.
Key words: stars: individual: SU Dra / stars: variables: RR Lyr / stars: fundamental parameters / stars: atmospheres
© ESO, 2002
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