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Early ComeOn+ adaptive optics observation of GQ Lupi and its substellar companion
We present an analysis of adaptive optics K-band imaging data of GQ Lupacquired in 1994 by the first generation adaptive optics system ComeOn+at the ESO 3.6 m optical telescope in La Silla. The data reveal a likelycandidate for the low-mass companion recently reported in theliterature. An a posteriori detection in the 11-year old data wouldprovide a useful astrometric data point for the very long-period (~1000yr) orbit of the GQ Lup system. However, the data is severelycontaminated by speckle noise at the given projected separation, whichdecreases the confidence of the detection. Still, from the data we canconclude that GQ Lup B is not an unrelated background source, butinstead a physical companion to GQ Lup A. We present here the reductionand analysis of the ComeOn+ images, as well as the results. We alsodiscuss the nature of the companion based on data and models availablein the scientific literature and examine claims made regarding theclassification of the object as a planet.
| CCD astrometry and instrumental Delta-V photometry of wide visual double stars. III - Differential measurements of often observed southern pairs
We present accurate relative positions and instrumental visual (BesselV) magnitude differences of southern wide star components. The meanaccuracy of the angular separation is 0.02 arcsecs, which corresponds to1.5 micron on the CCD chip, and of magnitude difference 0.007mag/exposure. The program pairs are targets of the HIPPARCOS mission andthey have been observed at least four times in the last 150 yrs.
| Interstellar reddening in the Southern Hemisphere. I - The UVBY beta observations
The uvby-beta photometric data obtained from a Southern Hemisphereobservational project is presented. A uvby-beta photometric network ofnearly 3900 A and early F stars has been established with the intentthat the stars serve as 'space probes' for measurements of interstellarreddening.
| The chemical evolution of the solar neighborhood. I - A bias-free reduction technique and data sample
The possible ways of measuring the age-metallicity relation for thegalactic disk in the neighborhood of the sun are discussed. It is shownthat the use of a field star sample chosen on the basis of effectivetemperature introduces a bias which results in a monotonic increase inthe metal abundance of the disk with time. However, if theage-metallicity relation for the disk can be shown to satisfy certaincriteria, the bias introduced in such a sample can be neglected: thegalactic disk apparently satisfies the criteria. It is concluded that asample analyzed through the use of uvby and H(beta) photometry inconjunction with a self-consistent set of theoretical isochronesprovides the least biased, most accurate estimate of the age-metallicityrelation for the disk.
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