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The N2K Consortium. VII. Atmospheric Parameters of 1907 Metal-rich Stars: Finding Planet-Search Targets
We report high-precision atmospheric parameters for 1907 stars in theN2K low-resolution spectroscopic survey, designed to identify metal-richFGK dwarfs likely to harbor detectable planets. Of these stars, 284 arein the ideal temperature range for planet searches,Teff<=6000 K, and have a 10% or greater probability ofhosting planets based on their metallicities. The stars in thelow-resolution spectroscopic survey should eventually yield >60 newplanets, including 8-9 hot Jupiters. Short-period planets have alreadybeen discovered orbiting the survey targets HIP 14810 and HD 149143.
| Chromospherically Active Stars. XX. The Giant Single-Lined Binary HD 161570
Spectroscopy of HD 161570 shows it to be a single-lined spectroscopicbinary with a period of 45.623 days and a nearly circular orbit. Theprimary star has spectral type G7 III, and the secondary is most likelya G or K dwarf. A high-resolution spectrum of the 3950 Å regionconfirms that the primary has Ca II H and K emission lines. Thelogarithm of the giant's lithium abundance is less than 0.9, indicatingthat it is not lithium-rich. From photometric observations covering sixseasons, we detected periodic short-term light variability with anamplitude ranging from 0.02 to 0.04 mag. We interpret these short-termvariations as due to stellar rotation and find that the rotation periodvaried somewhat from season to season, with a representative value of64.1 days. Thus, the very different orbital and rotation periods make HD161570 an asynchronous rotator. Low-amplitude, long-term photometricvariability was also seen. The giant's weak Ca II H and K emission,low-amplitude photometric variations, and relatively low vsini of 7.0 kms-1 indicate that this star is only modestlychromospherically active. This result, plus the spectral type andasynchronous rotation of the primary, suggest that it is just beginningto ascend the red giant branch.
| Radial-velocity measurements. V - Ground support of the HIPPARCOS satellite observation program
The paper presents data on 1070 radial velocity measurements of starsdistributed in 39 fields measuring 4 deg x 4 deg. The PPO series ofFehrenbach et al. (1987) and Duflot et al. (1990) is continued using theFehrenbach objective prism method.
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| קבוצת-כוכבים: | הרקולס |
| התרוממות ימנית: | 17h48m01.41s |
| סירוב: | +44°06'25.0" |
| גודל גלוי: | 7.699 |
| מרחק: | 75.019 פארסק |
| תנועה נכונה: | -25.3 |
| תנועה נכונה: | 25.2 |
| B-T magnitude: | 8.745 |
| V-T magnitude: | 7.786 |
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