2005PASJ...57...97S -
Publ. Astron. Soc. Jap., 57, 97-107 (2005/February-0)
Radial-velocity variability of G-type giants: first three years of the Okayama planet search program.
SATO B., KAMBE E., TAKEDA Y., IZUMIURA H., MASUDA S. and ANDO H.
Abstract (from CDS):
begin{HTML} We report on the radial-velocity variability of G-type giants based on the results of precise Doppler measurements of 57 stars that were observed for the first 3 years of the Okayama Planet Search Program. This program aims to search for planets around intermediate-mass stars in their evolved stages as late-G giants. We found that most of the targets with <i>B - V</i> < 1.0 have radial-velocity scatters of s ∼ 10 m s<sup>-1</sup>, with the most stable reaching levels of 6-8 m s<sup>-1</sup>, while those with <i>B - V</i> > 1.0 typically show s ∼ 20 m s<sup>-1</sup>. In total, about 60% of the targets are stable in radial velocity to a level of s < 15 m s<sup>-1</sup> over 1-3 years, and about 90% have s < 30 m s<sup>-1</sup>. We found that 4 stars (HD 30557, HD 34559, HD 68077, and HD 85444) show significant long-term radial-velocity trends, suggesting that they are probably orbited by unseen stellar or substellar companions. Three stars (HD 79181, HD 104985, and HD 141680) show periodic radial-velocity variations. HD 104985 is the first planet-harboring star discovered from our survey. The properties of the variations in these 3 stars have been, and will be, extensively discussed in separate papers. Relatively large, but not apparently periodic, radial-velocity variations of s > 30 m s<sup>-1</sup> are found in 4 stars (HD 41597, HD 134190, HD 161178, and HD 176598). For most of the stars without showing any significant periodicity, we can exclude companions with <i>K</i> > 50 m s<sup>-1</sup>, or <i>m</i><sub>2</sub>sin <i>i</i></sin> > 1.8 <i>M</i><sub>J</sub> (<i>a</i>/AU)<sup>1/2</sup>(<i>M<sub>*</sub>/M<sub>☉</sub></i>)<sup>1/2</sup> for orbital radii <i>a</i> \lesssim 1-2 AU.
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Journal keyword(s):
stars: late-type - - stars: planetary systems - - techniques: radial velocities
Simbad objects:
59
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