Issue |
A&A
Volume 399, Number 1, February III 2003
|
|
---|---|---|
Page(s) | 315 - 327 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20021789 | |
Published online | 05 February 2003 |
Doppler imaging of stellar surface structure
XIX. The solar-type components of the close binary
Coronae Borealis
1
Astrophysical Institute Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: KStrassmeier@aip.de
2
Department of Physics, Brandon University, Brandon, Manitoba R7A 6A9, Canada e-mail: rice@BrandonU.ca
Corresponding author: K. G. Strassmeier, KStrassmeier@aip.de
Received:
18
October
2002
Accepted:
29
November
2002
We present the first Doppler image for both stellar
components of the F9+G0 ZAMS binary CrB and found
evidence for the coexistence of cool and warm spots on both stars.
Cool spots appear mainly at polar or high latitudes while a
confined equatorial warm belt appears on the trailing hemisphere
of each of the two stars with respect to the orbital motion. We
also present an update of the TempMap imaging code that allows us to
solve the stellar surface temperature distribution on both binary
components simultaneously, including photometric input. Several
test reconstructions are performed to demonstrate its reliability
and robustness. Our new orbital solution results in very precise
masses for both components – good to 0.4% – and confirms the
spectral classifications of F9 and G0 for the primary and
secondary, respectively. The visual component,
CrB,
seems to be G4 rather than G0. All three components are on or very
close to the ZAMS which is also confirmed by the relatively high
lithium abundance of about twenty times the solar abundance.
Photometric light variations are detected with a period of
days that we interpret to be the rotation period
of both binary components. A 0
04 dimming in y together with a
reddening of 0
01 in
during the year 2000 suggests a
long-term spot variability compatible with a period of at least
260 days.
Key words: stars: activity / stars: starspots / stars: imaging / stars: individual: σ2 CrB / stars: late-type
© ESO, 2003
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