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The N2K Consortium. III. Short-Period Planets Orbiting HD 149143 and HD 109749
We report the detection of two short-period planets discovered at KeckObservatory. HD 149143 is a metal-rich G0 IV star with a planet ofMsini=1.33MJ and an orbital radius of 0.053 AU. The best-fitKeplerian model has an orbital period, P=4.072 days, semivelocityamplitude, K=149.6 m s-1, and eccentricity, e=0.016+/-0.01.The host star is chromospherically inactive and metal-rich, with[Fe/H]=0.26. Based on the Teff and stellar luminosity, wederive a stellar radius of 1.49 Rsolar. Photometricobservations of HD 149143 were carried out using the automatedphotometric telescopes at Fairborn Observatory. HD 149143 isphotometrically constant over the radial velocity period to0.0003+/-0.0002 mag, supporting the existence of the planetarycompanion. No transits were detected down to a photometric limit ofapproximately 0.02%, eliminating transiting planets with a variety ofcompositions and constraining the orbital inclination to less than83°. A short-period planet was also detected around HD 109749, a G3IV star. HD 109749 is chromospherically inactive, with [Fe/H]=0.25 and astellar radius of 1.24. The radial velocities for HD 109749 are modeledby a Keplerian with P=5.24 days and K=28.7 m s-1. Theinferred planet mass is Msini=0.28MJ and the semimajor axisof this orbit is 0.0635 AU. Photometry of HD 109749 was obtained withthe SMARTS consortium telescope, the PROMPT telescope, and bytransitsearch.org observers in Adelaide and Pretoria. These observationsdid not detect a decrement in the brightness of the host star at thepredicted ephemeris time, and they constrain the orbital inclination toless than 85° for gas giant planets with radii down to0.7RJ.Based on observations obtained at the W. M. Keck Observatory, which isoperated as a scientific partnership among the California Institute ofTechnology, the University of California, and the National Aeronauticsand Space Administration (NASA). The Observatory was made possible bythe generous financial support of the W. M. Keck Foundation. The authorswish to recognize and acknowledge the very significant cultural role andreverence that the summit of Mauna Kea has always had within theindigenous Hawaiian community. We are most fortunate to have theopportunity to conduct observations from this mountain. Keck time hasbeen granted by the National Optical Astronomy Observatory (NOAO) andNASA.
| Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| HIPPARCOS age-metallicity relation of the solar neighbourhood disc stars
We derive age-metallicity relations (AMRs) and orbital parameters forthe 1658 solar neighbourhood stars to which accurate distances aremeasured by the HIPPARCOS satellite. The sample stars comprise 1382 thindisc stars, 229 thick disc stars, and 47 halo stars according to theirorbital parameters. We find a considerable scatter for thin disc AMRalong the one-zone Galactic chemical evolution (GCE) model. Orbits andmetallicities of thin disc stars show now clear relation each other. Thescatter along the AMR exists even if the stars with the same orbits areselected. We examine simple extension of one-zone GCE models whichaccount for inhomogeneity in the effective yield and inhomogeneous starformation rate in the Galaxy. Both extensions of the one-zone GCE modelcannot account for the scatter in age - [Fe/H] - [Ca/Fe] relationsimultaneously. We conclude, therefore, that the scatter along the thindisc AMR is an essential feature in the formation and evolution of theGalaxy. The AMR for thick disc stars shows that the star formationterminated 8 Gyr ago in the thick disc. As already reported by Grattonet al. (\cite{Gratton_et.al.2000}) and Prochaska et al.(\cite{Prochaska_et.al.2000}), thick disc stars are more Ca-rich thanthin disc stars with the same [Fe/H]. We find that thick disc stars showa vertical abundance gradient. These three facts, the AMR, verticalgradient, and [Ca/Fe]-[Fe/H] relation, support monolithic collapseand/or accretion of satellite dwarf galaxies as likely thick discformation scenarios. Tables 2 and 3 are only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)or via http:/ /cdsweb.u-strasbg.fr/ cgi-bin/qcat?J/ A+A/394/927
| Mesures de vitesses radiales. VIII. Accompagnement AU sol DU programme d'observation DU satellite HIPPARCOS
We publish 1879 radial velocities of stars distributed in 105 fields of4^{\circ} \times 4^{\circ}. We continue the PPO series \cite[(Fehrenbachet al. 1987;]{Feh87} \cite[Duflot et al. 1990, 1992 and 1995),]{Du90}using the Fehrenbach objective prism method. Table 1 only available inelectronic form at CDS via to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Lichtelektrische UBV-Photometrie von Standardsternen und in vier Sternfeldern am Äquator
Not Available
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | נושא הנחש |
| התרוממות ימנית: | 16h42m07.32s |
| סירוב: | +01°14'30.2" |
| גודל גלוי: | 7.582 |
| מרחק: | 74.184 פארסק |
| תנועה נכונה: | 1.5 |
| תנועה נכונה: | -16.2 |
| B-T magnitude: | 8.047 |
| V-T magnitude: | 7.621 |
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