Issue |
A&A
Volume 397, Number 3, January III 2003
|
|
---|---|---|
Page(s) | 1151 - 1159 | |
Section | Astronomical instrumentation | |
DOI | https://doi.org/10.1051/0004-6361:20021559 | |
Published online | 21 January 2003 |
Precise radial velocity measurements of G and K giants*
First results
1
Kiepenheuer-Institut für Sonnenphysik, Freiburg(Brsg), Germany
2
European Southern Observatory, Garching bei München, Germany
3
Observatório Nacional, Rio de Janeiro, Brazil
4
Thüringer Landessternwarte Tautenburg, Tautenburg, Germany
Corresponding author: J. Setiawan, setiawan@kis.uni-freiburg.de
Received:
14
December
2001
Accepted:
25
October
2002
We present the first results of our precise radial velocity (RV) measurements of G and K giants.
A number of stars from our list of 80 targets have been observed for
14 months using the fibre-fed echelle spectrograph FEROS at the 1.52 m ESO
telescope in La Silla, Chile.
This sample increases the number of giants surveyed with precise
stellar radial velocity measurements at least by a factor of 10.
During this period we are able to estimate the long-term
accuracy of our measurement as better than 11 . We use the simultaneous Th-Ar
calibration and cross-correlation
technique to compute the radial velocity by applying a numerical template for K-type stars.
Standard deviation σ of mean radial velocity variations between
3
and 4 k
with timescales
between several days and years are measured for 21 of G and K giants which
are presented in this paper. Fifteen stars show definite variability
above 3 σ of our measurement uncertainties.
Two stars with RV variations above 800
are tentatively
identified as new binaries.
Although definitive trends between RV variations and stellar
evolutionary status cannot yet be established, all the luminous cool
giants of our sample seem to have significant radial velocity variations,
while those stars in the giant's clump region can be
either variable or constant.
Key words: stars: late-type / stars: variables: general / techniques: radial velocities
© ESO, 2003
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